Camshaft Advise - Will Original Survive Or Replace?

[XframeFX]

Looking for camshaft advise typical for all Flat Tappet Engines with Hyd. Lifters. The only specific is that my Nailhead has the original (114⁰ LSA) Camshaft with “Flat Lobes”.

 

First, I did all the wrong things back in 1993 with a valve job that included hardened exhaust valve inserts. The machine shop supplied a Felpro upper gasket kit in which I used all including Exh. Manifold gaskets. They also supplied 16 new Sealed Power 896 Hyd Lifters for solid pushrods (my request?)

Also, I was an advocate of synthetic oil living here in the North. So, my Nailhead always had that especially since the car would remain apart for many years. I was able to run the engine a couple times per year during its hibernation in the garage. I always ran it long enough to heat the pipes so no water remained. For 26 years this was the scenario. During this time, I learned of ZDDP missing from API Motor Oils.

2020 had my Riviera completed enough to drive that summer and into 2021 and last summer 2022, with ZDDP oil of course. No trips but, maybe 500 miles plus lots of stationary hours since 1993.

401 Nailhead has approx. 72K Miles and doesn’t smoke or leak. My only complaint is a “Resonant Thump” while waiting at a red light when at operating temp. Many say this is typical Nailhead and appears to be tamed somewhat.

 

So, my concern: If New Lifters with a crown were run on an old camshaft with flat lobes, would I have a ticking time bomb?

If incompatible, I would think I’d have a failure by now.

 

I finally got to do an inspection just now. I was expecting rounded camshaft Lobes. While not exactly “Crisp”, they look fine.

I managed to measure the lift of 14 Lobes and they all averaged .265”. Spec would be .268” for .431” lift at the Valve.

All Lifters had correct preload and all faces appear the same. No wear pattern this is because they rotate? They definitely have a crown. Again, not much mileage on them. Wonder what the face of a new Lifter looks like?

I no longer have those original Lifters with “Flat Faces”.

 

I purchased a new Timing Chain Set and T/A Perf’s mildest camshaft in January.

Doing the inspection, I could hear the chain dragging inside the cover. So, this is next.

Advise may say “change the camshaft anyway while doing the timing chain”. But I am not keen on dismantling the front of my Riviera. I spent over a week diagnosing stuck hood latches. Rather not disturb it.

Also, to purchase Lifters for the new camshaft, they will be for hollow pushrods and many break-in failures appear to be evident with current Lifters on the market (Youtube).

 

I said a lot here but needed to lay out the specifics. Thanks!

 

[EmTee]

If you place two lifters 'face-to-face' and the convex surface is still intact, you should be able to feel them rock against each other.  What I see looks like normal camshaft wear.  Your lobe measurements seem to corroborate that conclusion.  If intermittent use and the subsequent 500 miles of driving hasn't wiped any lobes, I would put it back together and drive it without hesitation.  Do replace the timing chain, as that can only help performance and reliability.

 

I recall having a camshaft lobe fail in the 283 I was running in my '56 Chevy in high school.  I had a second used 283 cam that I installed using all of the lifters from the original cam, except the badly worn one that rode the failed lobe.  In that position I installed a used lifter from another engine (probably the one I swiped the cam from).  Anyway, I put it together and drove it 'happily ever after', until I removed the 283/Powerglide in favor of the 327/TH-400 currently in it.  Maybe it was just 'beginner's luck'...

[60FlatTop]

That is quite a story.

 

My gut feeling would be to drive it 10,000 miles changing the oil three times over the period or at least one per year. Repeat that until you notice something that seems amiss.

 

A similar incident did come to mind while I was reading. Drive it!

 

[gungeey]

My free thoughts:

 

Your current cam looks just fine based on the limited pictures. Lifters may or may not turn on the cam. Most of yours are not. When you change your cam you should be changing your cam bearings. Unless you are doing the job yourself the machine shop will want to hot tank your engine which won't hurt as there's a residual skim coat of sludge on the valley walls, pushrods and I'm sure lots of hidden places. The camshaft bearings you will have to do one at a time fitted from rear to front with the new cam. It's a roll of the dice that either you or the shop get it right.

 

I personally don't like that the one lifter you are showing has lost it's shine, like it has worn through its finished surface. i wonder if they all look like that. The correct style lifters will not rock against each other as if the bottoms are conical. They will lay flat with a sphere on the outer edge to relieve contact on the lobe. If you are getting a cam from TA you should be getting their lifters, also.

 

Your experience from the 90's is pretty commonplace. Hardened exh seats and Felpro .045 gaskets. I laugh at the BS about "high nickel content". The same bozos keep parroting the same nonsense over and over. Nobody corrects them so it keeps on being said. They most certainly do get valve recession.

 

The big question begs asking: With all the maladies and roadblocks and parts hunts to no avail you have encountered with your car, why the digging into an engine that is running? Why not focus on just what is necessary to be done and start driving the thing?  I like wrenching as much as the next guy but the payback is to get behind the wheel. Life is too short to not reap the rewards of our hard work.

 

 

 

 

 

 

 

 

[avgwarhawk]

In my experience with installed hardened seats...they failed.  Engine burning oil like a well in TX.  Clacking.  I needed replacements. New pair complete valve job. No seats.  My lifters looked like yours.  These spin/rotate.  I replaced with new but left the cam in. It is a newer cam from a previously poor rebuild. I have about 3000 miles on it since putting it back together. No issues.  You cam and lifter appear ok.  From my understanding a cam will wipe soon after start-up.  

 

IMO, put it back together and run it. 

[XframeFX]

On 6/10/2023 at 8:59 AM, gungeey said:

With all the maladies and roadblocks and parts hunts to no avail you have encountered with your car, why the digging into an engine that is running? Why not focus on just what is necessary to be done and start driving the thing?

Right-on! However, the Heater Core required replacement, damaged front carpet replaced and while driver's seat is out the spring and pwr seat trans repaired. Further, while coolant and plumbing is out, do that timing chain as I can hear it drag inside the cover when barring over the crankshaft. That Timing Set is a must for reliability. So, yes, will have to drive it!

 

Progress thus far:

I did have to crack the AC and remove the Condenser to use a cordless Impact for removing that Harmonic Balancer Nut. So, now I'm re-thinking going the extra step changing out the camshaft even though the original appears happy with "crowned" HT896 Lifters.

I am again concern with the "aggressiveness" of the TA-112-401 I purchased in January. I opened the box in my hotel room and the Cam Card indicated much higher Lift than advertised: 401H.455"-210'/.468"-215',110'

It is now .470/.480, a big jump from the original .431"! This was TA's mildest Nailhead Camshaft.

Would my original AFB calibration be out with this Camshaft? Sparkplugs were finally a light Tan at the end of cruising season last year.

 

Expert comments on Specs below? Thanks!

 

[XframeFX]

Further to above. The Cam Card does not mention 4⁰ advance that Crower has ground into the Camshaft!

So, here is the same Camshaft with specs in Crower's format where they indicate the advance:

[NTX5467]

As to the lifters, it is perfectly fine to use new lifters on a used camshaft, with good lobes.  The bottom of the lifter is supposed to have some crown so they will rotate and wear longer.  The issue with getting the lifters back in the place they came from, with used lifters on the same camshaft, is getting their existing wear patterns matched, rather than otherwise.  The new lifters will make their own wear patterns as time progresses.

 

For general purposes, DO put moly paste on the new timing sprockets, chain, and the backside of the cam sprocket.  Other than the light (anti-rust) assy lube on them, they will not see any normal lube until things splash around as the engine runs.  That's my recommendation.  We used to pour a can of the thick GM Engine Oil Supplement over the cam before putting the intake manifold back on, but with everything covered in moly paste, no real need for that.  Most engine builders (and GM) have smaller squeeze bottles of engine assy lube these days.

 

Personally, I like Fel-Pro gaskets these days.  Their technology is far better than anything "back then", even with the greater build thickness of the composite gasket.  When the engines were built, the "best" thing was the stamped steel shim gaskets, plus they were obviously inexpensive, I suspect, which is one reason everybody used them.  The compression drop with the thicker gasket?  Add 2 more degrees to the base timing and you'll never miss it, from my observations.

 

IF the new cam might require some carb re-calibration, you can get the rod/jet package for such at Summit Racing for Edelbrock AFBs.  About $60.00 USD last time I looked?  I suspect everything should work with the AFB you have.  Usually, no major issues with a little bit longer duration and more lift.

 

Back in the later 1950s, everybody was in a "horsepower race", including Buick.  With the breathing limitations of the ports in the Nailhead motors, adding duration was one method to gain more power.  Except that customers allegedly complained about the "rough idle".  I suspect the "thump" you heard was a harmonic from the exhaust system rather than anything mechanical.  Yet you bought a cam "wilder than stock", as an upgrade?  So much for "smooth idle" . . .

 

Cam bearings are usually only replaced when the engine is disassembled and hot tanked during a rebuild situation.  Unless the Nailhead is different, each bearing is matched to the respective cam bearing, by diameter.  So they only fit in one place.  Generally, those bearings are prioritized for lube from the pump so they always have good lubrication and minimal wear.  The liquid potion in the hot tank destroys the babbit in the cam bearings, so they are removed BEFORE the tanking, which also exposes the oil passages behind them.  Getting the lube holes correctly positioned so that the lube supply leads the load area is important and might even be a deviation from the way they were clocked at the engine plant.  I remember my late machine shop operative saying something like that.

 

As for zddp, the alleged base minimum level of zddp for a "high lift" cam is 1000ppm, which is "SL" API rating oil.  With the higher lift (and resultant higher open spring pressure, as the springs will be compressed more) can increase the need for higher than that levels.  BUT I sold a GM Perf Parts ZZ427 crate motor in the early 2000s.  In the instruction sheet with the motor, it said to use "SM" motor oil, which was 800ppm of zddp.  But then those motors were "fire tested" at the engine plant so the cam had already been broken in prior to crating the engine for shipment.

 

Although the earlier API ratings (SM = 800ppm, with some brands getting into the higher 600 range), then came the newer SN, SN+, and now SP ratings.  This latest rating is spec'd for 900ppm of zddp, with the diesel oils (as Rotella T6 syn are still about 1100ppm, from virgin oil tests posted at www.bobistheoilguy.clm forums).  The latest SP rating also has a component to measure "pin wear" on the pins which hold things together on the timing chain assys!  Which means that wear past something like "anything" is not acceptable, so if it will be fine with the timing chain pins (and their higher unit-loading), it might well be that using a SP synthetic oil would be just fine for your cam lobes and lifters.  Finding a brand of normal syn oil with a good dose of "moly" in it can't hurt, either.

 

I concur, put that thing back together and drive it.  IF the thicker head gaskets might have resulted in a 10 horsepower drop at WOT, consider too that by the time that power gets to the ground, it's only about 7 horsepower lost.  So, add 2 degrees to hot base ignition timing and don't look back . . . unless, it starts to ping on acceleration or something like that.

 

Back when all we had was 91 pump octane super unleaded gas, the OEMs had already gone to the composition head gaskets AND most aftermarket piston makers had instituted a "de-stroke" of their pistons by lowering the piston pin location by .020".  Both measures to make the rebuilt engines operate better on the low-octane fuels of back then.  I've not heard anybody complain about a decrease in real-world power on those engines (many of the 1960s engines were built with 10.0+CR ratios), unless they were in non-bracket drag racing where every horse to the ground was important AND a chassis that could best deliver it there.  BTAIM

 

Back when GM put out the edict that "All engines built after April 15, 1971 will run on unleaded fuel", the Buick officials said their engines were already there, due to the higher nickel content of their cyl heads.  But they had to go with the edict and use induction hardened valve seats when they were really not needed on Buick engines.  It has been noted many places that putting hard seats in Nailheads can be a bit tricky so that water is not struck in the machining process to fit the hard seats.  FWIW.

 

Sorry for the length,

NTX5467

 

 

[XframeFX]

12 hours ago, NTX5467 said:

As to the lifters, it is perfectly fine to use new lifters on a used camshaft, with good lobes.

Thank-You NTX, appreciate the "length". Knowing this, I would have not purchased the Camshaft. I was concerned the original cam now has "crowned lifters", not like-for-like replacement. I was only after a Timing Chain Set and Gaskets when vaca'ing in Phoenix. The Camshaft was just-in-case as I had yet to do an inspection of my Nailhead. Also, It was simple to slip all the parts in my checked bag rather than logistics to Canada. Very convenient to have TA Performance at my destination! I considered a new Timing Chain cover as a just-in-case purchase but refrained. They had a stack of them on the floor.

 

I was given a tour of TA Perf's facilities. Their specialty appears to be aluminum castings and machining of them. A great Buick source!

 

I knew beforehand the TA Perf cam had .020" more lift. But, the cam card inside indicated .050" additional Lift! In follow-up with them, some confusion over rocker ratio. Lift values did not agree for 1.5 or 1.6 ratios? All Nailheads are 1.6 ratio, simple

 

The Felpro Intake gaskets were beaded steel shims. Had I remembered, I would've re-torqued the intake in my trouble-shooting. New gaskets are composite. I only mentioned the 1993 gasket set because there's mention how Felpro head gaskets leak at the oil port and are NG. (TA Perf has steel shim head gaskets BTW). Head gaskets are not part of this work scope as they seem fine.

 

If I continue without replacing the Camshaft, should I take apart those Seal Power HT896 Lifters for cleaning? If so, this could set me back a bit.

 

The Resonant Thump at idle appears in the front floorboards that received copious sheets of Dynamat. Reason why I'm perplexed.

 

If I don't use the Camshaft, I'll use the included packet of Lucas Assembly Lube inside the box!

 

I plan to be back on the road soon! Thanks Again!

 

Another look at another Lifter Face and corresponding Lobe. They all appear the same.

[telriv]

ANYTHING above a .250" lobe lift & the ratio is reduced DRAMATICLY. 

It is 1.6 ratio @.250 lobe lift.

Do a search & you will find my results.

I WILL NOT type out with one finger why.

It would take me hours typing with one finger.

 

Tom T.

[gungeey]

35 minutes ago, XframeFX said:

Thank-You NTX, appreciate the "length". Knowing this, I would have not purchased the Camshaft. I was concerned the original cam now has "crowned lifters", not like-for-like replacement. I was only after a Timing Chain Set and Gaskets when vaca'ing in Phoenix. The Camshaft was just-in-case as I had yet to do an inspection of my Nailhead. Also, It was simple to slip all the parts in my checked bag rather than logistics to Canada. Very convenient to have TA Performance at my destination! I considered a new Timing Chain cover as a just-in-case purchase but refrained. They had a stack of them on the floor.

 

I was given a tour of TA Perf's facilities. Their specialty appears to be aluminum castings and machining of them. A great Buick source!

 

I knew beforehand the TA Perf cam had .020" more lift. But, the cam card inside indicated .050" additional Lift! In follow-up with them, some confusion over rocker ratio. Lift values did not agree for 1.5 or 1.6 ratios? All Nailheads are 1.6 ratio, simple

 

The Felpro Intake gaskets were beaded steel shims. Had I remembered, I would've re-torqued the intake in my trouble-shooting. New gaskets are composite. I only mentioned the 1993 gasket set because there's mention how Felpro head gaskets leak at the oil port and are NG. (TA Perf has steel shim head gaskets BTW). Head gaskets are not part of this work scope as they seem fine.

 

If I continue without replacing the Camshaft, should I take apart those Seal Power HT896 Lifters for cleaning? If so, this could set me back a bit.

 

The Resonant Thump at idle appears in the front floorboards that received copious sheets of Dynamat. Reason why I'm perplexed.

 

If I don't use the Camshaft, I'll use the included packet of Lucas Assembly Lube inside the box!

 

I plan to be back on the road soon! Thanks Again!

 

Another look at another Lifter Face and corresponding Lobe. They all appear the same.

Get 16 snapple bottles. Or any thick plastic bottle. Not those super thin water bottles. Mark the cap 1-16. Put your disassembled lifters in each bottle. Fill half way with gas. Shake and stir till done. Put it into a screen pasta strainer. 

 

Put up a No 🚭 Smoking sign

 

Stay tuned for more cheap tricks 😆 

[NTX5467]

Aftermarket cam manufacturers started to quote "Duration @ .050" lift" many years ago.  Although there is a SAE procedure (which the OEMs are supposed to use), the aftermarket started to use the .050" duration specs so all cams could be compared for duration under the same rules).

 

Getting the cam "just in case" was a good move, as was the carry-on bag deal, too.

 

Taking the lifters apart for cleaning is seldom done any more, if at all.  In one repsect, if the oil and have been changed regularly, I would suspect that all is well for them internally.

 

Back in the middle 1990s, GM came out with a TSB for "cold engine knock" on Chevy 350 V-8s.  The main thing was "one oil change with Mobil 1 motor oil."  I thought that was very interesting, at the time.  Then I learned that motor oil with an ester in the base oil stock (esters were what we smelled in high school chemistry, which had a sweet banana-type smell to them), from a post in www.bobistheoilguy.com motor oil forums) . . . the ester addition dissolves sludge in the motor, as a cleaning agent.  So, after you get everything back together, you might try a change of Mobil 1 (they have some motor oils with 1000+ppm of zddp in them, Truck and Turbodiesel formulations, most probably) if desired.  Motul is another brand where when you take the cap off of the oil bottle, it smells of sweet bananas, from what I discovered about 8 yrs ago at an autoshow.

 

One thing I started doing on the steel shim intake gaskets is to take the black high-heat silicone sealer and put it in the beads (backside) of the gasket.  Scrape it smooth with a Mr. Gasket gasket scraper, then let it cure overnight.  When torqued down, it makes like a "Print-O-Seal" gasket for a better total seal of the ports and such.

 

Thanks for the additional information,

NTX5467

[telriv]

That's a half way way of doing the cleanout.

They NEED to come apart to clean the machining debris out that MOST contain rather than trying to just do a surface flush.

Leave the debris in there & it wears the lifter internally.

Don't forget the debris is what is used to size the lifter bore with the body of the plunger so it will wear internal surfaces pre-maturely.

Now you will have only hours, at most, overnight before they will have leaked down completely.

Diesel oils are NOT made for the higher RPM potentials of gas engines as they have a tendency to foam causing air bubbles.

Last time I looked air was NOT a lubricate.

Just my thoughts.

 

Tom T.

[XframeFX]

7 hours ago, telriv said:

ANYTHING above a .250" lobe lift & the ratio is reduced DRAMATICLY.

Above? Don't you mean "BELOW .250" Lobe lift"?

 

Lowest measured Lobe Lift in my table above is .256"

If gross lift is .431" it would calculate .269" at the Lobe.

 

Going the extra step replacing the Camshaft would require removing the grill and I should do it since I have it. It's just that the TA Perf Cam appears too aggressive. Variables like vacuum, idle smoothness and carb calibration concerns me. Measuring a few Lobes, they are indeed .300" Lift. Not too concerned LSA is 110 vs 114 for original. Not a perfect smooth idle but then, I don't have it up to now.

 

7 hours ago, telriv said:

Do a search & you will find my results.

I did camshaft research and this site which led to my discovering original Nailhead Lifters did not have a crown and Lobes not tapered. I thought they were. Knowing this is why I purchased the Camshaft and looking for advise on this post.

 

Thank-You Everyone!

[NTX5467]

All oils have a component in them to prevent foaming . . . gasoline-rated and diesel-rated.  Even when Rotella T carried gasoline and diesel engine ratings.  Most diesels big diesels are limited to about 3000rpm.  Not due to the fact the diesel lube oils "foam", but more likely due to the amount of weight slinging around IN them.  The bulk of gasoline engines seldom break 3000rpm unless they have some deeper-than-orig equipment rear axle ratio.

 

When the components of the valve lifters were machined and possibly finish honed, every machine I've seen which bores and hones has huge amounts of flushing oil going onto the items being machined.  Everything "built/machined to size".  You might want to pump up the lifters or let them sit overnight in motor oil, though.

 

From my limited experience with a 110 degree lobe center cam, you might need to put weaker springs in the distributor to get it to act better off-idle and at lower rpm levels.  Allegedly the tighter lobe center will pump up mid-range torque, but 114 degree lobe centers makes for more intake manifold vac at idle.  It's all a balancing act.

 

Cam lobes are tapered, but unless you pull one out and check it in a fixture, you'll probably not notice.  One "low taper" lobe cam is for the OEM '69 Chrysler 6-bbl 440.  It came from the factory with a cam with less lobe taper, which combined with appropriate lifters, better handles the higher spring pressures of that motor.  FWIW

 

ONE reason why cam manufacturers will not warranty their cams unless you bought their lifters, has to do with the fact that THEY know what THEIR lifters are.  But many machine shops mix/match things from their own knowledge of what is what.  BTAIM

 

The options include putting the new lifters and timing chain in, lubing everything up very well, putting it back together and driving it this season.  If things go well, continue as desired.  If not then plan on pulling it out over the "off-season" and sending it to a quality machine shop who knows how to build Nailheads.  

 

Enjoy!

NTX5467

[gungeey]

1964 Buick Factory Service Manual p 2-29

 

I have other year manuals also. They all say the same thing regarding lifters rotating on the cam lobe.

 

So now what? 

Edited June 16, 2023 by gungeey (see edit history)

[XframeFX]

On 6/16/2023 at 8:21 AM, gungeey said:

1964 Buick Factory Service Manual p 2-29

Yes, I read that too, before I learned original Nailhead Lifters did not have a crown and Lobes did not have a taper.

It also mentions "Replace":

Camshaft and Lifters work hand-in hand. I do not want to do this again, the reason for my OCD on this.

 

For NEW Camshaft specs, I think Tom T's "ABOVE .250" Lobe Lift" is not a Type-O. I think actual lift at the valve is not necessarily gross lift of .25"X1.6. The 114 LSA cam states lift of .431".

So, if max Lobe lift should be .25", my concern of the TA Perf camshaft being .3" is valid. Again, both versions of the Cam-Card at the top of this post. No comments as yet. Stay away?

 

As for the 500 or so miles clocked on those Sealed Power HT896 Lifters, no alarm bells. The crowned face appears OK with those light spring pressures. Enough scrutiny.

 

1) I keep flip-flopping but, will likely proceed with original camshaft.

2) Clean out all Sealed Power Lifters

3) Install new front crankshaft seal inside Timing Chain Cover. New Bolts

4) New Water Pump

5) Proceed with 9-Key Roller Timing Chain Set. Original Camshaft has 5⁰ advance built-in? Just join the dots?

I have determined true TDC. That Dennis Manner chart has specs at .002" lift and no Lobe centers. Any checks at this stage short of degee'ing the original cam with new timing chain?

 

Edited June 17, 2023 by XframeFX (see edit history)

[NTX5467]

Nothing wrong with OCD, just that it needs to be on the top of a bell curve rather than on either side of the top of the curve for best results.  The trick is noticing when one is about to be on the right hand slope of the curve rather than on the top of the curve.  Then talking one's self out of the increased anxiety which might lead to that right hand slope!

 

Back in the time prior to about 1979, the OEMs could measure cam duration specs as they desired.  There were a few years in the middle 1960s when Chevrolet obviously measured the ramps in their figures, as the same cam had wildly larger duration numbers, for the same cam, as the model year prior.  Although the SAE specs for such were what everybody else used.  Lift was more valid, though.  The "lobe separation" figure seemed to become talked about about the same time as "Duration @ .050", although the lobe separation issue had probably been in camshaft engineers' vocabulary for many years, as they worked to capitalize on engine design/operation with the engine designers.  Then came the "Ground __ degrees advanced", which might have been compensation for the 4 degrees retard which many OEMs put into their stock production cam sprockets for alleged emissions reasons.  In a time when multi-keyway cam sprockets were not commonly-available, relying on offset bushings for the same result.

 

In the traditional sense of things, advancing the production OEM cam would tend to increase the lower rpm torque, as retarding by the same amount would bleed-off some low rpm torque but add top end horsepower.  Which could be a tuning tool for cars with large engines and skinny tires, if used properly. 

 

The "ground __ degrees advanced" issue seemed to be more "hollow rhetoric" than not.  If the lobes were advanced, "advanced from what?"  Which would mean, to me, that if you took the open/close event specs, retarded them by that amount, THAT was the original cam lobe specs?  Sometimes, it might sound like "Our cam is better because its lobes are grond advanced __ degrees", than not.   I', skeptical enough to request to see the two engine dyno runs to verify the additional power curves.  Dyno comparisons which would not be available, I suspect.  BTAIM

 

Enjoy!

NTX5467

[XframeFX]

I just stumbled upon this youtube clip on Nailhead Timing Chain replacement in-car.

I did this in June and cracked open my AC to remove the condenser anticipating camshaft replacement but did not proceed.

Video is very basic. I could add much more important detail.

I used the same 9-keyway roller timing chain and struggling with it set me back 2.5 days. Finally installed, the chain was NOT tight as shown in the video.

Looking out for Part 2:

 

 

[DeAnna Fleming]

Given everything you've done, if the lifters and cam lobes are looking good after all this inspection, I wouldn't stress too much about it being a problem waiting to happen. If something was off, you'd likely have noticed major issues by now with all the care you've put in.

 

As for swapping out the camshaft while you're at it, it's a tough call. If your Riviera is running fine and you're not keen on tearing into the front end again (especially after that hood latch ordeal), it might be best to leave well enough alone for now. But, if you need parts down the line, remember there are affordable fuel pump injectors for sale. They've got a wide range of parts that could help out if you ever decide to go deeper into your engine work.

Edited February 20 by DeAnna Fleming (see edit history)

[Paul K.]

Good camshaft discussion thread below from years ago. Many of us have been down this road before and my journey has a brief explanation in my post from 2011.   

 

 

[XframeFX]

5 hours ago, DeAnna Fleming said:

Given everything you've done, if the lifters and cam lobes are looking good after all this inspection,

Thanks. With local summer miles, all is fine. No change in operation. Nice that there is no dead-band observed at the distributor Rotor when rocking the crankshaft.

 

Some indecisiveness on camshaft and lifters. I would've proceeded if it was an actual 112 LSA (Schneider) not the 110 I purchased. I returned that camshaft.

Degreed a camshaft for the 1st time. Along with data from the inspection, I now have a good assessment on the state of my Nailhead.

In my youth, got lucky not degreeing a performance camshaft. No online calculators back then, no computers even!

The crankshaft sprocket was the only issue.

4 hours ago, Paul K. said:

Good camshaft discussion thread below from years ago.

Hmm, yes, good. Have not seen that post before.

[NTX5467]

I went back and downloaded the earlier PDF of the '59-'66 cam specs for good measure.  In those earlier days, LCA was not a real spec to look at in determining which cam to use.  I'm also not aware of what the Nailhead engine "likes" in that respect.  Many of the Chevrolet and Chrysler OEM cams were on 112-114 LCA, by comparison.  Many of the 1980s+ aftermarket cams (specifically CompCams and similar) were on 110LCA.  Apparently, tightening the LCA toward 110 increases mid-range torque.  Lunati seems to be one of the few to head toward the 114 LCA on their aftermarket cams.

 

When cams are re-ground, the base circle of the cam is decreased so that when the lobes are shortened, the lift of the lobe is maintained.  Not sure of the lobe shape, though.  Schneider used to built their own cams in the 1960s, but never was a big player as Isky was.  I would be curious about their restoration process.

 

When I installed a Cam Dynamics 266 in my '77 Camaro 305 (upgraded to a Holley 4160 (emissions-spec for a '75 Impala 350) and the single-plane Holley 28-Z intake ("Z" for Zora's design with a resonating tube connecting #7 and #8, so #7 could receive a more even charge as it fires right after #5, which is located in the single-plane manifold, right beside the entry of #7 port).  I had to re-curve the distributor to get back some of the off-idle response and power.  

 

I was not really happy with how things worked out.  I took the car to the dealership shop one Saturday to use the big SUNN diagnostic machine (which could check air/fuel ratio and HC/CO emissions).  With things set as best I could tune them, the car idled at 600rpm in "P", in "D" the vac dropped to 10.5" Hg.  Power brakes still worked as they did with the stock cam and 2bbl.  The 10.5" Hg in "D" is significant as the two-stage power valve in the Holley's first activation was rated at 10" Hg.  When I throttled into the motor to get it to 10" Hg, there was only minor enrichment until the vac level dropped to the 5.5" Hg "full open" level.

 

The particular cam's duration was 210 @ .050"  with .440 lift on s 110LCA.  So, to me, this is the max spec duration for a 5.0L motor that is expected to idle smooth in traffic with the stock converter.  When the 305 was replaced with a 355 and that same cam and intake, it seemed to work much better as to torque output (as both engines had the same stroke).  The 355 has the '86 Corvette factory aluminum heads, which were pre-Vortec in combustion chamber design, which should have helped a bit, too.

 

Allegedly, the old original CompCams "High-Energy" series cams were ground 4 degrees advanced.  Never did really understand that.  I knew that retarding a cam 4 degrees would help top-end power while also bleeding off a bit of low-end torque to make hooking-up with street tires a bit better at the drag strip.

 

Unfortunately, I fully understand that the Buick NailHead engine family is very antique, but so was the Chevy 348/409 before it saw a resurgence in the 1990s, such that new heads and many other "hot rod" things have appeared in recent years.

 

I determined years ago that many OEMs were trying many new things in their "modern" V-8 engine designs.  Everybody was watching what everybody else was doing, too!  The OTHER situation was that these engines had to be able to be installed into frames which were designed around INLINE engines.  Looking at the exhaust manifolds of the Chrysler Hemi V-8 illustrates this!  Which could also be the reason that non-Chevy V-8s of that time were "different" with their longer strokes and taller decks.  The next redesign of the frames/bodies allowed the front frame sections to be widened to better accommodate the wider V-8 engines which were to come.

 

I feel the Buick NH was the result of needing a competitive V-8, put into the earlier chassis, and needing the better low-end torque to do these things with 3.5-area axle ratios and the DynaFlow transmission.  AND, as Buick was the "smoooth" division of GM, their engines had to idle smooooth and operate nicely, too.  So, that resulted in the head ports the NH had.  Plus a few other design attributes which were torque-oriented rather than 6000rpm power oriented.

 

In looking at some of the head port flow numbers in Team Buick, I was shocked to see such good numbers.  BUT flow numbers are just that, numbers, not related to how the flow into the combustion chamber might be biased and how all of these things interact.  Then considering the flow OUT of the engine and into the smaller-diameter exhaust systems of back then.

 

I've wondered how a fully-modernized NH might run and produce power with a self-learning EFI (which also did full ignition control), nicer exhaust manifolds, and a quiet lower restriction exhaust system.  THEN pairing these things with piston crowns for a better-optimized combustion process AND pistons with the current OEM "mm" ring packages and bore finish!  And, of course, a camshaft with "modern tech" for improved power and lower emissions/better fuel economy.  Even asymetrical lobes which keep the valves at max lift for 10 degrees of crank rotation.  AND do all of this while maintaining the OEM appearance of things, when possible.

 

Just some thoughts, observations, and dreams,

NTX5467

Edited February 16 by NTX5467 (see edit history)

[NTX5467]

UPDATE:  I had heard David Vizard talk about how cam companies do not fully understand the specs on the cam cards.  At the time, I suspected there was some truth in that, but it would also mean the cam companies were not giving the purchaser the correct information about what they built and sold to their customers.  Which caused some ????.  I also had heard him talk about his proven method to determine what LSA was needed for best power.  In this case, "Power" would be for a race engine, not a street engine.  BTAIM

 

I happened onto a YouTube video by "Cattledog Garage" which started to explain these things.  The video is just over 96minutes long, with a good bit of prior information getting to the "meat" of things at about the 48 minute mark.  The first part is the backdrop to what comes later in the video, though, so find a comfortable seat.

 

He has many of the formulas which Mr. Vizard uses to determine camshaft LSA, .050" Duration, etc.  The orientation is to determine an optimal LSA, THEN choose duration, and such.

 

As with many of the longer YT videos, keep the cursor poised over the "Skip Ad" area to click for better continuity, then in order to better understand what is being said, use the cursos to PAUSE the video to understand the on-screen dyno runs and formulas, too.  Also, have some paper and a writing instrument close-by to fill in the numbers for the formulas presented.  Or take some screenshots with your phone.

 

This video shows a date of "A Year Ago", with another video of his showing a more recent time.

 

www.YouTube.com/watch?v=STRx2yU6AuA

 

The "128 Formula" is stated to work with small block Chevy motors and some others, with a different number for other popular engines.  Of which Buick is not in the list, but after watching the full video, you can get an idea of how the NH Buick can fit into the mix.  In order to get an approx ".050" duration", multiplying the factory duration numbers (in the chart presented a few days ago) by .80.  Hopefully this video can give you a better understanding of what the cam card numbers really mean.  

 

Happy watching!

NTX5467

Edited February 18 by NTX5467 (see edit history)

[NTX5467]

In thinking about what I saw in the second video, looking at the power curves and dyno run sheets of Adam's dyno runs, past about 4000rpm the LSA did not matter much at all, but below that it could influence things a good bit.  I would like to have seen the numbers on his dually 383, though.

 

When plugging numbers into the "128 Formula", the 110 LSA made more sense as to lower-to-midrange torque.  But I believe he touched on lengthening the LSA for better idle quality, which would also lessen low rpm torque at the same time.

 

In the dyno run sheet compilation, the more-optimum the LSA got compared to the others, as great as the difference might have been, it appeared to seldom amount to more than 30 lbs-ft of torque.  Which CAN be significant in vehicle advertising or on a race track.

 

Yet when doing an OEM engine for the masses, some power/torque is usually "left on the table" to work better for more people in daily use.  Plus leave some room for the aftermarket people to be able to sell cams to people who "want more".  As the "128 Formula" can assist them in finding one.

 

Most cam companies sell cams for "Engine Families" rather than specific engine sizes.  Engine size can affect LSA, along with different intake valve sizes.  So unless a cam is customer-ground for a specific engine and use, the LSA can be off-optimum by a few degrees, sometimes.  Which is probably where duration comes into the mix, as well as port flow capacities (intake valve sizes)?  As if, in the case of Chevy V-8s, they optimize a cam for the most popular size (350) and then offer it for any other small block Chevy engine (in the family) letting the purchaser determine if it will work for them.  

 

Under that thought, when I was first looking around for a better cam for my '77 Camaro 305, I considered various things and realized that bigger engines need more duration than smaller engines did.  I devised a formula to reflect such.  I had several friends who had installed the popular CompCams 268HE cam in their 350s, which worked very sell, but I had a 305 with highway gears.  So after much slide rule activity, determined that the next size down would be wheat I needed for the smaller engine.  Which worked well for me.  I further expanded my computations to include other engine families of the time, too.

 

In other looking around, I remembered Vizard talking about Harvey Crane.  I finally found a Crane Cams Master Catalog, from about 2018 or so.  It had the history of Crane Cams and LOTS of other good cam information in there.  Including their CD electronic ignition conversion kits, using points as triggers or their LED system.  

 

In the Crane catalog, I was reminded of how many cams they had.  Some only a few degrees of duration apart, or very similar duration times with a different LSA for different applications.

 

But only 1967 and newer Buick V-8 cams, unfortunately.  Guess I need to seek out a 1968 master catalog?

 

In these looking-around adventures, I also discovered many companies (in various parts of the USA) which do camshaft restorations and re-grinds.  In one video, Vizard mentioned Demos Cams and one in the Pacific Northwest also was mentioned by somebody else.

 

Enjoy!

NTX5467

Edited February 19 by NTX5467 (see edit history)

[arnulfo de l.a.]

NXT! Thank you for all the VALUABLE info you provide. Much appreciated!

[XframeFX]

4 hours ago, NTX5467 said:

Adam's dyno runs, past about 4000rpm the LSA did not matter much at all, but below that it could influence things a good bit. 

Thanks Willis. If one were to build a 350 SBC, simply follow someone's success for a particular application.

However, for our Nailhead engines, most people don't have the luxury of numerous test-cell "pulls" producing print-outs to help with choosing the best cam.

 

My method for choosing a camshaft was to not veer too much from OE. However, the table of OE camshafts had data based on the .002" SAE method. This had me degree the original camshaft using the .050" method.

With .050" data, I decided on a profile with a 112 LSA. However, the Cam-Card inside the box indicated 110 LSA. Maybe it would've degreed differently but I wanted to keep it new to return to the Vendor.

 

Interesting, the 128 calculation. But, who will do a custom camshaft for a Nailhead? Still have to choose what's available out there. For me it was the Schneider grind with 112 LSA.

 

In general, there are "engine builders" for a particular application and there are "engine designers" employed by giants such as GM. The latter has decades of research. However, there's no disputing engine builds from the likes of Smokey Yunick!

 

[NTX5467]

To me, part of Adam's credibility comes from the fact his grandfather worked for Chevy and Pontiac, AND made the acquaintance of Smokey.  His father continued the legacy by having a machine shop, which Adam said he was working at 10 yrs old.  Learning from his father and grandfather.  So he's "third gen".  He is in the Pacific Northwest, so no real reason to know of anybody on the east coast, so his orientations were developed independently from Vizard.  Much of the first section of the first video is taken up with these things.

 

It appears that much of the whole LSA issue centers around when the intake valve opens.  From there, then comes duration and lift.  When the exhaust is fully open then determines the complete LSA situation.

 

Vizard has a few videos out on his "128 Formula", which he devised from his experiences.  He also has comments about how what is on the cam card is not always accurate, which means "degree the cam for verification".  BTAIM

 

The "Mr. T" which Adam mentions has the orientation that increasing exhaust duration helps top end power, specifically, which even his dyno runs does not indicate, although torque below 4000rpm is affected.  I don't know who that is, nor is that an issue to me.  BTAIM

mp

Once one understands the ports and how they work best, specifically on a common Chevy 350, then they can look at other heads' ports and see why they don't flow as they should, by comparison.  Plus what can be done to improve them.  THEN, look into the combustion chamber and the intake manifold.  THEN look backward to the various GM brands and their cyl head/camshaft interactions.  For example, in the middle 1960s, Pontiac's OEM camshafts usually had valve lifts in the .425" range.  Higher power versions of their 389s and 421s had modestly longer durations.  Why?  It was noted that flow "stalled" above about .430" lift.  So they were walking the tight rope between acceptable idle for their normal customers and being able to have competitive or better power figures for advertising purposes.  The Pontiacs were also long-rod motors, which was another (unknowing) dynamic in getting mediocre ports to flow well.

 

BUT outside of camshaft things, the OTHER big deal I came across is "Plateau Honing" of cylinder bores.  I came across that on a Lake Speed video where he was talking about a lot of things.  Plateau honing is where the initial hone is done with a diamond honing item.  A rougher cut than normal, then followed with a different abrasive to get to the "plateau" finish at the desired size.  So I searched for "Plateau Honing Rottler" and found that YT video which explained how the computerized Rottler honing machine does that finish.  With the accompanying surface finish graph and related numbers.  Such a finish works with former-OEM width piston rings, but seems to work better with the current-OEM "mm" ring packages.  End result, about +100 MORE horsepower in a Winston Cup engine with those items alone AND decreased bore wear at the same time.  Getting some piston manufacturers to do a run of .030" OS pistons for Buick NH V-8s with the new "mm" ring package might be easier than getting a run of flanged-top air filter elements, just cost a bunch more.  

 

In these lookings-around, I was reminded that Buick NH engines had a big following, though not as large as the original Chrysler Hemi, in particular modified drag racing classes in the later 1950s.  With superchargers and all.  Which would mean that some old equipment might be hiding somewhere in somebody's shop or information of such in somebody's alive brain?  If it happened with Chevy 348/409, it could happen with Buick NH engines, too.  Don't see how long you can hold your breath, though.

 

Enjoy!

NTX5467

 

 

Edited February 19 by NTX5467 (see edit history)