Ugh...my timing chain is slopped out

EmTee · January 5

10 hours ago, arnulfo de l.a. said:

I am in the process of degreeing the original camshaft to a 1973 455 i am working on for installation into a 1968 rivi gs.

Hmmm, are you using that camshaft just because you had it available, or is it supposed to be good for some particular reason (e.g., low RPM torque)? Normally I wouldn't consider installation of a smog-era cam in a pre-1970 high compression engine.

arnulfo de l.a. · January 5

4 hours ago, EmTee said:

Hmmm, are you using that camshaft just because you had it available, or is it supposed to be good for some particular reason (e.g., low RPM torque)? Normally I wouldn't consider installation of a smog-era cam in a pre-1970 high compression engine.

I agree on the smog cams not being up to par for a presmog engine. This is the original cam to the 1973 455 . The original 68 gs engine was ruined due to severe detonation. The person that rebuilt it back in the 80’s left an enormous amount of deck clearance . So i sourced a 455 to replace it. One of the reasons i am considering using the original cam is because the cam and lifters are already broken in and in excellent condition.Also i am not looking to build a high performance engine. Ability to run on pump gas and reliability are what is most important to me. I hope to take are few 5k trips on it. I am not dead set on using the cam. I am degreeing the cam so i can make comparisons of whats available in the aftermarket in case i decide to go new. I will make a final decision when the time comes where i have to decide . Im in the beginning stages of the build right now, disassembly ,measuring ,cleaning then off to the machine shop for a sonic test, rebore , assuming the sonic checks out, and a clean up and squaring of the block and head deck surfaces.

XframeFX · January 5

21 hours ago, arnulfo de l.a. said:

Very cool! Care to share some numbers? I would be most interested lobe seperation angle , intake open , intake close and whatever else you would like to share.

I was apprehensive doing this (Camshaft/Lifter/Timing Chain replacement) and thought I was genius in doing a dry run BEFORE replacing parts.

I tested for TDC at Cyl #1. Then incremented the balancer the full 360° using masking tape with Zero at the new mark (about +2° from mark). The smallish diameter meant less accuracy than a pro-degree wheel but, it served the purpose. It will eventually wear off.

Of note, I made my own TDC tool with a 14mm fitting from my Compression Tester Kit, a syringe and a piece of vacuum tubing with a paint stick mark.

Once dis-assembled, I expected some wiped Camshaft Lobes but, all appeared OK visually. I went further by measuring the lift for each Lobe and ended up not changing the camshaft.

There are two online calculators for entering acquired data using the .050” method. One accepts valve timing data and calculates area, duration, CL to intake. The other kind of back calculates using duration, LSA, CL to Intake and then plots-it-out. Running both calculators independently concurs with each other, very cool, especially the plot!

I ran both calculators for several Cam Cards which is NOT actual. Only my camshaft data was actual.

Specs for my original #1359442 were using the old .002” advertised method on that Dennis M. List and is useless for comparisons outside that list. So, it was good to have my camshaft with .050” data to compare with other cam-cards.

It turns out the original camshaft did have built-in advance.

I would’ve changed the camshaft if the new TA-112 I had on-hand didn’t have such an aggressive profile and reputable Lifters could be sourced. Quality of Flat tappet Hyd Lifters have deteriorated, even Roller Lifters! However, replacing the camshaft would’ve introduced too many variables in my trouble shooting for thumping in the passenger compartment while waiting at a red light in Drive. It remains unresolved.

Retaining the original cam, I got to keep my in-service replacement Lifters after cleaning them out knowing some leaked-down within a ½ day depending what position my Nailhead stopped in. “Go with the Devil you know”.

When shopping for camshafts, I would not use advertised specs. Request the cam-card for each camshaft you are considering, then run the .050” data through the calculator that plots-out the data. Only then can you make an informed decision! See my tables below that I used for comparison.

In my case, the original camshaft compares to the Melling SBC-3 or Elgin E-564-S which is a stock grind.

A nice profile would’ve been the Schneider #112 Camshaft, not too aggressive. It would’ve been a good upgrade if I was sold quality lifters to go with the package.

The two Calculators for doing your 1973 455:

http://www.wallaceracing.com/camcalc.php

https://mgispeedware.com/camshaft-calculator/

Degree Results with Nylon Timing Chain. Left is results FROM one calculator using test data, Right is using another calculator with data FROM Blue Box (Left):

image.png.e75fe3bbe3c6832ab25fe6485673273f.png image.png.1513f6a748f1aa557a035d71638d812e.png

image.png.292a96ba16b25616e08216d1b5d1ecf1.png

image.png.a69f29143067971d51e260a373d58d56.png

image.png.5a9f7b0fa67265612a02e484f4542b01.png image.png.e728a0be5aaab7785633aef42a501862.png

image.png.fda30ccb2e38dad22de2501572e8089c.png

image.png.a6e5a1503bc234815b4b36f747e240b4.png

Edited January 6 by XframeFX (see edit history)

telriv · January 5

You could use Chevy lifters as they are sold by the thousands & the end results are usually quality & a plus are usually less costly.

You just need to use hybrid pushrods.

5/16ths.one end & 3/8 the rocker arm end.

Other than the above I see NO down sides & have used MANY.

Tom T.

Edited March 14 by telriv (see edit history)

NTX5467 · January 5

As to "advertised duration", there are SAE specs on how to measure that. Seems like the "Lift from Cam Base Circle" on Intake is .006" and Exhaust is .008". From what I understand, that accounts for the amount of the "ramp" on the lobe, so it is not counted. Although in about 1963, as the duration specs on Chevy V-8 cams suddenly had extremely large duration numbers, they counted the ramps in those numbers, apparently, as the part numbers of the cams did not change.

When the ".050" Duration" figures appeared, that was a tool to use to compare any aftermarket cam, one to another. Not saying the advertised durations of the aftermarket cams were incorrect, just that it gave the customer a way to compare cams with a common value of lift. At the time, a Chrysler engineer claimed you could take the advertised (SAE Spec) and multiply it by .80 or .85 to approx the .050" lift duration, on OEM Chrysler cams. Possibly other OEMs are similar, as they are supposed to be using the same SAE procedures?

@arnulfo and @XframeX, the one time I did a cam specs check (on a '72 Chry 440 NOS short block), I used a magnetic dial indicator, measuring off of a pushrod inserted into the top of a valve lifter, with the engine on an engine stand. I procured a Mr. Gasket degree wheel, used the dial indicator to verify TDC, and bent a piece of stiff wire to indicate TDC on the degree wheel. Then assembled the valve lifter/puchrod/dial indicator assy for reading lobe lift. The first cam I checked was a new comp Cams 268HE (from the mid-80s when they were new). I cleaned the #1 lobes and put a thin coat of motor oil on the lobes and lifter base. The next cam I checked was an original NOS Chrysler Purple Shaft Street HEMI cam I bought from Gratiot Auto Supply in the late 1970s, NOS. Same proceedure. I took readings when lift started, max lift, and lift ended. Unfortunately, all of those pages on the legal pad are archived at this time. I know the CompCam item checked exactly as the cam card and other literature stated. The big surprise was that their "asymetrical lobes" were really there! Keeping the intake valve at max lift for 10 degrees of crankshaft travel, for the stated "increased area under the curve" to yield longer-duration power with less real duration. The unsurprising issue was that the NOS OEM cam held the max lift value for a quick ONE degree of crankshaft movement.

Now . . . "How I Spent Yesterday (01-04-2024) Afternoon"

I had happened onto some videos on the "Muscle Car Solutions" YouTube channel on camshaft lifter failures. After watching that, he mentioned a future interview he had with Billy Godbold (formerly of CompCams, not in private consultancy). So I watched that 1 hr long video, with the "main stuff" happening past the 40minute mark. with much before it, too. Plan on watching the whole deal! Several comments about cam break-in and related engine rpm. Also mention of the new "DLC" coated hydraulic lifters. "DLC" = "Diamond Like Carbon", for better durability, but only Chevrolet applications available at this time (see @telriv post above).

As to Billy's book, he talks a lot about it and many of the variables in choosing a good cam. It's like 200 pages and costs about $36.95USD at CarTech Books, fwiw. As he mentioned, lots fo reading there!

@arnulfo, in the rebuild of the '68 motor, how did the rebuilder leave "too much deck" on the engine? Were "export" pistons used to lower the compression ratio? Or what? Considering the engine had 10.0CR to start with? Why is it not "fixable"? Just curious.

As to "OEM smog era cams", many were not different from prior cams, depending upon which brand of engine is being talked about, by observation. For example, Chev and others used a cam sprocket with a 4 degree retard built into it, OEM. It was easy to tell if the sprocket was retarded by where the dot was in relation to the peak on the sprocket where the timing chain "tooth" was. Ford did similar on the 460s.

As good as the 430s were on power AND fuel economy, for a slightly bigger motor with a lower compression ratio (and the same cam), something of that "sweet spot" motor vanished with the lower CR. I believe they had the same cam on both motors, IIRC.

As to your used cam, did you keep the valve lifters separated by which lobe on the cam they were originally assembled to? IF NOT, you would need to coat the lifter bases and lobes with moly assy lube prior to assy, pour the GM EOS (thick) over the lobes through the lifter valley, and do a complete break-in procedure again to let each lifter "get to know" a new cam lobe.

I commend @XframeX for his supplied data on the cam specs!

Many aftermarket cam manufacturers cut their cams on 110degree LCA specs. Most OEM cams are 112-114degree LCAs, which can yield a better idle quality and higher idle vac levels in gear. Lunati has some 112LCA cams, though, but not sure if they are Buick V-8 cams, of either generation. Many cam people will claim the 110LCA increases mid-range power a bit over OEM, but I wondered about that.

Back when my '77 Camaro LT 305 had 92K miles on it, I upgraded it to a Holley 28-Z (single plane, full plenum divider, but with the "resonating channel" between the #7 and #8 cyls, to give #7 a better charge, as #5 and #7 pulled from the same corner of the plenum and fired consequtivly), an emissions-spec Holley 4160 (1975 Chevy Impala 350), and a Cam Dynamics "Energizer" 266 cam (210 @.050, 110degree LCA, .440 lift). O hac chosen that cam to work with the 2.56 rear axle in the car, rather than the wilder next-step cam. It was equivalent in specs to the CompCam 260HE cam of that time. On the first drive after break-in, it did OK, but was not stellar by any means. So I messed around with the advance curve and helped it some, plus some playing with the initial advance advance setting. When done, it only dropped my daily mpg by .4mpg, with more power. So that was good. in later times, I upgraded the 4160 to an emissions-spec 4175 for a '79 L82 Corvette. Immediate 2mpg jump! To 19.66-20mpg average. The night before the 305 was swapped for a same-cam 355, it did 23.5mpg on a 60 mile freeway loop at about 60mph. Not bad for a 525K mile OEM engine with 8.5CR.

Just some thoughts, experiences, concerns, and questions,

NTX5467

arnulfo de l.a. · January 6

John! Thanks for that man, great job. I respect your improvising skills, very impressive.Surprised to see no overlap. Should make for a smooth idling engine. Wonder if your thumping issue is being caused by a weak cylinder or possibly an out of balance rotating assembly. I have also wondered if torque converters are balanced. When they are full of fluid that makes for alot of rotating mass. Could it be that the fluid acts as a dynamic balancer?Hope you get it figured out.

NXT, the pistons sat .040 in the hole and he used a .050 compressed gasket for a total of .090 in the hole. Horrible quench ! Should be between .035- .045 max. He also bored it .030 over and the damage from detonation would take a minimum of another .030 for a total of .060 overbore. Even if a sonic test showed the cylinder walls were good to go that big, ( which is a crap shoot due to core shift ) i dont feel comfortable With that much overbore. The only other option would be to resleeve. Not too big on that idea because it would require the decks to be machined and the numbers would be removed. Being its the numbers matching engine to the 68 rivi gs I am not crazy about that idea either. So for now the block will sit in the corner of my garage. Yes I did keep the lifters and push rods separated by cylinder and intake / exhaust valves. I have not yet disassembled the heads to the 455. Want to cc the combustion chambers first.When I do take the heads apart I will also separate from the keepers to the valves.

RivNut · January 6

22 hours ago, XframeFX said:

I was apprehensive doing this (Camshaft/Lifter/Timing Chain replacement) and thought I was genius in doing a dry run BEFORE replacing parts.

I tested for TDC at Cyl #1. Then incremented the balancer the full 360° using masking tape with Zero at the new mark (about +2° from mark). The smallish diameter meant less accuracy than a pro-degree wheel but, it served the purpose. It will eventually wear off.

Of note, I made my own TDC tool with a 14mm fitting from my Compression Tester Kit, a syringe and a piece of vacuum tubing with a paint stick mark.

Once dis-assembled, I expected some wiped Camshaft Lobes but, all appeared OK visually. I went further by measuring the lift for each Lobe and ended up not changing the camshaft.

There are two online calculators for entering acquired data using the .050” method. One accepts valve timing data and calculates area, duration, CL to intake. The other kind of back calculates using duration, LSA, CL to Intake and then plots-it-out. Running both calculators independently concurs with each other, very cool, especially the plot!

I ran both calculators for several Cam Cards which is NOT actual. Only my camshaft data was actual.

Specs for my original #1359442 were using the old .002” advertised method on that Dennis M. List and is useless for comparisons outside that list. So, it was good to have my camshaft with .050” data to compare with other cam-cards.

It turns out the original camshaft did have built-in advance.

I would’ve changed the camshaft if the new TA-112 I had on-hand didn’t have such an aggressive profile and reputable Lifters could be sourced. Quality of Flat tappet Hyd Lifters have deteriorated, even Roller Lifters! However, replacing the camshaft would’ve introduced too many variables in my trouble shooting for thumping in the passenger compartment while waiting at a red light in Drive. It remains unresolved.

Retaining the original cam, I got to keep my in-service replacement Lifters after cleaning them out knowing some leaked-down within a ½ day depending what position my Nailhead stopped in. “Go with the Devil you know”.

When shopping for camshafts, I would not use advertised specs. Request the cam-card for each camshaft you are considering, then run the .050” data through the calculator that plots-out the data. Only then can you make an informed decision! See my tables below that I used for comparison.

In my case, the original camshaft compares to the Melling SBC-3 or Elgin E-564-S which is a stock grind.

A nice profile would’ve been the Schneider #112 Camshaft, not too aggressive. It would’ve been a good upgrade if I was sold quality lifters to go with the package.

The two Calculators for doing your 1973 455:

http://www.wallaceracing.com/camcalc.php

https://mgispeedware.com/camshaft-calculator/

Degree Results with Nylon Timing Chain. Left is results FROM one calculator using test data, Right is using another calculator with data FROM Blue Box (Left):

This list of OE cam specs is incomplete when compared to the chart that Dennis Manner posted in a Riview some years ago. It does not include 1964, 1965, or 1966 or which cams were used with the 2x4 engines. No cams are listed for the years I mentioned when cam timing went from 12 degrees to 5 degrees.

RivNut · January 6

This is a reprint of Dennis Manner’s chart. It can be found on the team Buick website.

https://www.teambuick.com/reference/nailhead_cam_specs.php

OldGerman · January 10

On 1/3/2024 at 8:29 PM, arnulfo de l.a. said:

Frank i am curious as to how much slack you have. Can you please elaborate?

So I‘ve measured new true roller timing chain slack. With one side under tension the other side had about 8mm slack. I was surprised, that this leads to only 1 degree retard angle on the cam sprocket ( equals 2 deg. On the crank sprocket). Please take into account that these measurement was not very precise.