'63 Riviera Rochester Carburetor - modern alternatives ?

[OldGerman]

Hello Riviera Guy’s,

 

This was certainly already more often a topic here, but my search for information did not lead to the desired result.

 

My ’63 Riviera had a small fuel consumption problem ( >40liter/100km = 5.9 Miles/Gallon).

 

I know, there could be a lot of potential reasons which lead to poor gas mileage.

 

Anyhow, I’m thinking about a future replacement of the original Rochester Quadrajet Carburetor with a brand new part equipped with modern technology like e-Choke and vacuum secondary’s.....  

It might be the better solution for improved gas mileage rather than a 50 year old rebuild carburetor.

 

Do you know any modern spread bore carburetor, with the correct flow size, matching the Riviera intake manifold, the linkage system and the original small diameter Riviera Air Cleaner snorkel (plug and play) ?

Small modification to the linkage system will be ok to me, but I want to continue to use the original air cleaner and intake manifold, instead of aftermarket parts.

Is there a steel plate available to mask the pre heating air flow system on top of the intake for use of an E-choke carb. ?

 

I recently did an overhauling of the Rochester Quadrajet with an rebuild kit, but I did not achieve the expected result.

Thank you all in advance,

Frank

[RivNut]

Your 63 has a Rochester 4GC.  It is not a spread bore, it's a square bore.  Blocking off the exhaust passages to the carb will not have any effect on an electric choke; the heat for the choke you have comes from a hot air tube connected to the exhaust manifold. The  passages in the intake are designed for exhaust gasses to heat the base of the carb to help with cold weather operation.  Is your heat riser valve in the exhaust opening fully once your engine warms up?

 

An Edlebrock AFB or AVS will bolt on to your manifold, but you won't be able to use your air cleaner without an adapter.

 

A Quadrajet (spread bore) carb has two smaller primaries and two huge secondaries. It takes a different intake manifold to bolt a Q-jet to you engine.

 

At the mileage you're quoting, I think you've got deeper problems than changing carbs will fix.  Let's see what others have to say.

 

 

[msdminc]

Frank, when I got my 65 with a 401 cid engine and a Rochester 4GC carb similar to yours - I was getting about 6 mpg.  I cleaned and rebuilt the Rochester, with a kit I got from THE CARBURETOR SHOP, 204 EAST 15TH STREET, ELDON, MISSOURI 65026, click HERE for their website.  It solved a vacuum leak I had that was impacting performance, as well as the accelerator pump leak, and my mileage went to 12+ mpg.  Changing the wires and plugs improved fuel economy to regularly get over 14 mpg.  The cleaning will do wonders.

 

Rock On

 

gord

[Jim Cannon]

Frank-

I would recommend installing a fully rebuilt, proper Carter AFB from the 1963 model year.  Everything will connect up without modifications.  You can put an electric choke on it if you want.  Add the stainless steel plate under the carb (very important).

 

Check the thermal "heat riser valve" in the passenger side exhaust manifold.  Make sure it is moving and is open.

 

If you want to do so, you can modify the AFB to only operate on the front 2 barrels.  The back 2 barrels are locked out all the time.  Not as much fun to drive, but it will burn less fuel.

 

For fuel consumption, these cars do very poorly when stopping and starting a lot.  They do better out on the open road where you get up to speed and maintain it.

 

 

 

[60FlatTop]

It is really hard to do a carb rebuild that wrong. I am thinking you need to take a good look at your brakes.

 

5.9 MPG  is a lot of liters. I guess you need literhosen for fuel line

 

Be careful about home brew fuel systems modifications. Here's how a Canadian guy got the kind of mileage you are getting:

 

[jrbartlett]

Another easy check is the vacuum advance in the distributor -- plus the mechanical advance weights -- plus overall timing.

[carbking]

Frank - mileage such as you are experiencing would certainly be frustrating.

 

First - your question about a modern spread-bore using your manifold and air cleaner was answered by Ed (Rivnut). A misunderstanding that has confused many enthusiasts is the term "Quadrajet". GM occasionally referred to the 4GC carburetor (such as you have) as a quadrajet. However, carburetor now referred to by most as a quadrajet is the 4MV carburetor. The differences are quite obvious. The 4GC (produced from 1952 to 1966) has throttle bores which are either the same size, or very close to the same size) and is referred to as a square-bore carburetor. The 4MV (produced from 1965 to sometime in the 1980's) has throttle bores that are markedly different in size. The front (primary) bores are approximately 1 3/8 inch, and the back (secondary) bores are approximately 2 1/4 inch. Also, the size of the diameter of the air intake was increased.

 

So there is no spread-bore carb that will fit your intake without using an adapter, AND YOU DO NOT WANT TO USE AN ADAPTER!

 

Your 1963 Riviera could have come from the factory with either a Rochester 4GC or a Carter AFB (neither of which are currently being produced). Different enthusiasts prefer either the Carter or the Rochester but I will flat tell you that if you buy one of each that is professionally rebuilt, have a mechanic place either on the engine and let you drive, then place the other on the engine and let you drive; you won't really be able to tell if the mechanic actually changed the carbs. Both are great carbs.

 

Jim Cannon suggested possibly switching to the ORIGINAL AFB. The AFB did gain a following among enthusiasts that modify their engines, as there are more re-calibration parts available for the AFB than for the 4GC, so re-calibration for a modified engine is much easier with the AFB.

 

The new clones which look like AFB's will not fit your air cleaner; and more importantly, THEY WILL REQUIRE TOTAL RECALIBRATION TO WORK WELL ON A BUICK ENGINE!!!

 

You can install an electric choke on an original AFB, but if you try to drive the car at an ambient of less than 40 degrees F. you better have the telephone number for the nearest tow truck!

 

Lots of words above, but wanted to answer your questions.

 

Now - suggestions:

 

Find out WHY your mileage is so poor. As you mentioned, many possible causes, but for mileage that bad, I would first check that the automatic choke is completely opening. Once the engine is at normal operating temperature, the choke plate should be in the vertical position (completely open).

 

Also, check your brakes for the possibility of a brake not completely releasing, and also check your tire pressure.

 

You will get other suggestions on what to look for on the engine, but I would check the choke function FIRST.

 

And (opinion) your Rochester or a correct ORIGINAL AFB either are far superior to any shiny new carburetor you can acquire for your Buick.

 

Jon.

[jsgun]

On my ford, it likes to percolate the gas in the carb after driving, causing gas to dump down the intake. Causes extremely bad gad mileage, because so much of it is being spilled. 

[OldGerman]

 

Thank you all for your usefull tips.

 

If I would summarize, there is no modern Carburetor in the market which will fit without modifications to intake, linkage or air cleaner.

As I said, I know that there are many other factors influencing the fuel consumption.

I’ve now also converted the ignition system to Petronix 1, replaced spark plugs, wires, coil,  distributor cap and finger, cleaned the pre heating ( hot air tube and intake manifold passages)

2 of 8 new Delco spark plugs did not work ! Engine runs on 6,5 cylinders. Changed back to the used Bosch WR9FC and the engine runs smooth again. I will exhange to new champions later.

 

@ Ed,

 I was always thinking, the terms “spread bore and square bore” defines the intake to carb bolt pattern :-)  You never stop learning.

The heat riser valve in the Exhaust is in wide open position. The Bi-metal spring is broken, so I fixed it in the wide open position. I do not run the car in cold climate condition. Will fix that later as well.

@ Jim,

You are right, I have a lot of stop and go traffic here in my region and a lot of hills. There is no wide open land with straight road here.

But my 1966 Chrysler 300 is running at 25 liter/100 km =  9,4 MPG at this conditions.

@ Rock,

I’ve used a carburetor rebuild kit purchased from CARS Inc. It was very complete.  Now I need to monitor and control fuel consumption over the next few gas tank refills.

 

@ 60FlatTop,

LOL,  thank you for the video. 

Don’t get me wrong, I had this massive fuel consumption before carb rebuild !! 

I hope it is much better now, but I did not had enough miles driving to confirm that.

I was asking for a general future carb swap ! 

But the toilette flush matches the way the fuel indicator drops during driving before rebuild J.

 

@ James,

Timing is properly set, distributer was removed, cleaned and converted to a Petronix I ignitor. Vacuum and mechanical advance works fine.

 

@ Jon,

Thank you for clarifying the different carburetor designs and terms. I was definitely confused by that.

I totally agree, I will not change to a spread bore carb. I was looking for improvement in fuel consumption, maybe throttle response beyond a optimal rebuild original carb. But this is maybe an illusion.

I currently have a Rochester 4GC, that’s for sure.

During removal of the carburetor before rebuild, I noticed that 2 of 3 small outer crews holding the iron cast base plate (throttle valves) in place where loose.

I guess there was a huge leakage / air passage.

I was also wondering about this unusual bolt pattern. 1 big center screw and 3 small outer screws. Why not 4 equally distributed screws ? (see picture attached).

Thank you also for your suggestions :

Brakes are completely rebuild and free/released.

Choke was not ok before rebuild. The linkage was bended and choke valve did not completely open ! This is fixed now !

Once I have made new measurements on fuel consumption, I will let you know the result. I will keep you posted ;-)

 

Thank you all,

Frank

[telriv]

I have taken the new Edelbrock carbs. & converted them over using an original AFB supplied by the customer by swapping tops, all the jets, metering rods, springs, etc. & swapping out the throttle shafts. Now the original air cleaner fits & ALL the linkage is correct. You now have a NEW carb. that's actually built better/smoother than the original & in some instances easier to service if ever needed.

[carbking]

Frank - looking forward to your post on revised fuel mileage. I believe your fixing the choke will do wonders.

 

In your response to Ed, you mentioned being confused about square-bore/spread-bore referring to carb bolt spacing. Here is an article I did some time ago which may help you understand the various manifold/carburetor mounting bolt spacings:

 

http://www.thecarburetorshop.com/Four_barrel_mounting_flanges.htm

 

As to your question concerning the one large/three small throttle body to bowl screws: the large screw will accept more torque and is less likely to loosen on its own than the small screws. The large screw is centered in the area where vacuum leaks would occur.

 

Telriv - concerning your comment about the clones. By changing throttle shafts you eliminate one of the major clone issues, and if you change all the jets, rods, springs, venturii, airvalve, etc. you now have a Buick calibration; but you still have a main casting (clone) which is significantly inferior to the original, as the clone is vacuum-cast and the original was pressure-cast. And a slotted pump well rather than the superior inlet check valve of the original. The only advantage is that it is shiny! Blasting the original with either plastic media or crushed walnut shells will make the superior original just as shiny, if shiny is what you want.

 

Jon.

[60FlatTop]

The toilet tank analogy must be as old as toilet tanks. Flush toilets became common after carburetors and my Dad, who grew up in the 1920's and '30's, said "stepping on the gas, like flushing a toilet" fairly often.

Thinking back over 50 years of driving, the only gas suckers I remember were a 1970 GMC 1/2 ton Camper Special and a 1970 Cadillac Eldorado. They were my 10-12 MPG cars. Everything else in memory was better.

The spreadbore quadrajets were on both those cars. Over the years I got the know the feel of a heavy QJ float. And there was a plug in the bottom of the base that would leak. I learned to start the car, let it idle a bit, and then pull the carb fast and look into the manifold for excess fuel. On a 4 GC and others there is an odd chance of a leaky float if you get into an untenable situation. When the carb is apart put the floats in hot, but not boiling, water. If fuel is in them it will escape from the seam in a little jet of bubbles. Vaporize it all and solder or replace the float. I think I have done that twice, seem to remember older single or two barrel Carters needing that. But it is always a good test to be sure.

 

I enjoy working on carburetors. There is a book on the shelf above me from McGraw-Hill, not four feet away, that my Mother bought me in 1959. It is one of five and all about carburetors. It is a combination of theoretical and empirical that I still pull down for an evening's reading material. Understanding what happens and what each part does makes this easier. And recognizing parts lying on a bench is quite satisfying. It is hard to figure a reason to buy a new or rebuilt unless it is missing.

 

A very expensive, fully restored car car in to me one time with a bunch of erroneous diagnosed problems. I was surprised to find I needed a slide hammer to get the metering rod pistons out. That was a AFB. It is the only one I replaced, as I recall, and I combined two into the final job.

 

Looks like just some random thoughts. Maybe it will help someone.

Bernie

[RivNut]

8 hours ago, OldGerman said:

 

 

Thank you all for your usefull tips.

 

 

 

 

 

I’ve used a carburetor rebuild kit purchased from CARS Inc. It was very complete.  Now I need to monitor and control fuel consumption over the next few gas tank refills.

 

 

 

Chances are the kit you got from CARS is a Zip Kit, or universal for many Carbs.  Get the exact one you need from Jon "Carb King."  You'd be surprised at the difference a specific kit will make.  Who knows, you may have used a wrong gasket and you're hurting your performance.  As much as I like to tinker and work on cars, I leave carburetors to the professionals.

 

Ed 

[carbking]

Ed - thanks for the plug, but in this instance I really believe Frank is going to be pleasantly surprised with his fuel economy after fixing the choke.

 

It is really amazing how much extra fuel that choke can force into the engine.

 

Jon.

[XframeFX]

I had the same thought as Telriv on swapping the top of an original AFB onto an Edelbrock performer. So, now I know its "do-able". Thank-you! Should I use a top with no provision for an internal filter and avoid the top with a sintered bronze filter? So many variations!

Another idea I'm pondering is swapping out my '63 AFB primary throttle shaft with one from a '64 LeSabre 300 cu in AFB (4331S). This will allow me to dump the Dynaflow Variable Pitch bellcrank and gain the electric Kickdown/Variable Pitch switch in a future ST-400 swap. It appears this throttle shaft will fit the newer AFBs as well!

As for a choke. I'm using an electric choke and it burned-out. Not a name brand unit. Will purchase a Carter electric choke next time

I stopped looking for a spreadbore manifold. The Squarebore manifold offers more flexibility and the AFB itself has many possibilities.

Lots of learning here, Thank-you, John

[XframeFX]

Oh, any particular Edelbrock carburetor the will accept the old AFB top for a 401? Telriv?

Thank-you, John

[telriv]

ALL of them.  For a performance increase you could use a 750.

[OldGerman]

Now, 6 years later after about only 2,600 miles driven, The excel list containing all my fuel bills and mileage entered, calculates an average of below 25liter/100 km = 9.4 Miles/gallon. I think that was acceptable given the traffic and landscape conditions in my area. A few longer Autobahn rides had significant lower consumptions. 

I‘m now in process of a second rebuilt with a kit from carb King together with a new timing gear chain.

That will take some time but I hope to be ready for the next season.

Frank.

[XframeFX]

Frank, so asking for tips on rebuilding your Carburetor this 2nd go around? It's a Rochester 4GC?

Usually our Nailhead Rivieras were fitted with Carter AFBs

With the rebuild kit you are committed to another rebuild followed with some on-the-fly  tuning. Check for usual vacuum leaks everywhere! Spraying carb cleaner at suspect places such as gasketed flanges. I even went as far as spending big $$$ to rebuild a functional power brake booster (only to receive it back painted!). The vacuum accumulator tank never held vacuum after shut-down. No leaks and the external check valve appeared functional. So I thought it was the power booster. Oh well, the only change is clean power booster internals and paint, that's it!

Strip down your carburetor and find an ultra-sonic cleaner to start.

Being a dry winter, I have chapstick handy and smear my gaskets with it so I can re-use them. With all my trouble-shooting, I'm running low on gaskets!

 

Personal opinion of my Nailhead is that it is a crude pig. Carburetor dries-out in 2-weeks,  guzzles fuel, stinks, thumps and clattering lifters. Symptoms I can only ignore for so long but is reality. Our Nailheads are noted for excessive fuel consumption. My tuning has produced minor gains. Being a project car, it does minimal mileage so not too concerned about MPG. However, the poor MPG equates to a short range. The fuel tank is too small! Road trips will require frequent refills.

 

The alternative since the original AFB 3503 appears alien to my 1963  JT engine, is to replace. I've been eyeing the Edelbrock 750 CFM Performer 1411. So much negativity on E-Clones but I still have an old 600 CFM Edelbrock Performer that when new out-of-the-box and directly on a SBC 350 produced  excellent results, 20 MPG even!

E-Clone negativity for one was vacuum formed castings. However, I planned on swapping the top from my 3503 to allow use of the original pancake air cleaner. The casting experiencing wear from sacrificial metering rod pistons IS the top. But now, with no like-for-like replacement elements, there's now an excuse to find another air cleaner solution as well. The Edelbrock Performer is an improved carburetor that for one became a universal carburetor but is still a great choice for a square bore unit. Edelbrock has spun-off variants such as the AVS. 

Back to the Edelbrock 1411, it will require a spacer to clear the 1 9/16" primaries.

What would be ideal is a good ole 1966 Rochester Q-Jet with Variable Pitch Bellcrank and spread bore intake. This would be the right direction for improved MPG. Bonus would be that WAAAA at WOT no matter what air cleaner you have!

 

During my trouble-shooting, you can never have too much data. For just my little project, I can't justify a PICO-Scope, Wide-band Air/Fuel Ratio analyzer, gas analyzer and associated Sensors. If I had access to these resources, I'm sure I'd find the culprit, smoking gun or, even a silver bullet!

 

So, I discovered a recent start-up from Iowa with a youtube channel who along with a partner developed the "Carb Cheater" for a 4-door Maverick. It has an "Auto Tune" feature which will adjust for minor operating anomalies to fixed or adjustable set-points, I question this feature since they do not disclose how it's accomplished. I can only assume it bleeds vacuum to attain results. However, I commend the creative pair for producing what a major corporation will spend major resources to accomplish the same thing.

I already like "Carb Cheater" for it's sensors, Data Acquisition/Logger and HMI ("human machine interface" through bluetooth to Android app). At $539 CAD, a major expense for me but it is up for consideration. Warning, it is in "BETA" format with limited production.

https://thecarbcheater.com/

[BulldogDriver]

John,

 

If you are going to an Edlebrock carb the better choice would be 

https://www.summitracing.com/parts/edl-1913

 

You will also need a tuning kit if you go with the AFR gauge.

 

This AFR gauge will do the job quite well, been using it for several years now. I welded a bung into each down tube of the exhaust pipe below the manifolds to check both banks.

https://www.summitracing.com/parts/avm-30-0300

 

The Rochester 4GC was also used on 401 blocks in the Riviera. I have one sitting on the shelf that came off of mine when I changed over to an Edlebrock. I also added a pressure regulator on mine. The Edlebrocks are sensitive to that. I don’t think the newer carb is going to improve MPG much. My improvement came from the overdrive transmission.

 

The Martins have several articles about carburetors  on their site that might be worth reading.

http://centervilleautorepair.com

 

I’m sure others will chime in with their input.

 

Ray

Edited January 7 by BulldogDriver (see edit history)

[RivNut]

Fact. The tops of the original carbs will interchange with the new ones.  Bolt your old top onto your new carb and your OE air cleaner will fit.  Still have to jury-rig some way to activate the kick down and variable pitch feature. Best bet? Rebuild the OE cab.

[carbking]

Things worth at least considering:

 

When Federal Mogul was still selling the downgraded redesigned AFB's, they were basically replacements for small block (up to 400 CID) Chevy engines, and calibrated accordingly. This was also true of the aftermarket genuine AFB's when Carter was still making them. There was no reason to do aftermarket AFB's for Buick, Chrysler, or Pontiac; as Carter still sold O.E. carbs for these applications. Chevrolet migrated to Holley for square bore carb for small blocks greater than the 327.

 

I don't know what calibrations Edelbrock is using or they are available, but it is quite easy to look at original Carter specifications, as they are readily available:

 

Carter 3921s/625 CFM (Buick 401) step-up rods used were 0.068.5 (high vacuum) x 0.063 (low vacuum)

Carter 3923s/625 CFM (Buick 425) step-up rods used 0.0695 (high vacuum) x 0.063 (low vacuum)

 

Contrast to:

 

Carter 3720s/675 CFM (Chevrolet 327) step-up rods were 0.073 (high vacuum) x 0.063 (low vacuum)

 

Two contrasts:

 

(1) the obvious is that the Chevrolet rods have a significantly greater change in volume from the high vacuum step to the low vacuum step than the Buick rods

(2) less obvious is that the Chevrolet engineers used a 675 CFM carburetor as the small block is capable of greater RPM and greater air demand even for less cubic inches than the Buick

(3) the Buick engineers figured that the 625 CFM was sufficient for a street engine (we are NOT talking trailered race cars here).

 

Taking the differences further, and I didn't take time to do pictures; the auxiliary air valves for Buick are of a different profile than those for the Chevrolet. Run into this all the time with Pontiac owners as the Pontiac and Buick engines will often have a hesitation when the secondary is engaged if using Chevy air valves.

 

Does Edelbrock offer a large selection of air valves of different masses and different attack angles, as did Carter?

 

Are specifications (air bleeds, restricters, bypasses) available from Edelbrock so they could be calibrated similiarly to the original Buick calibrations?

 

Or is one on one's own with a tuning kit, a lathe, a vertical mill, and an AFR meter?

 

The air cleaner question has been answered; what about the other questions?

 

As far as the step-up piston wear is concerned, I do not know what steps Edelbrock has taken. When Carter released the AFB in 1957, the step-up pistons were brass, and the castings wore badly. After a couple of months, Carter replaced the brass pistons with aluminum ones. The aluminum pistons were machined from a softer metal beginning in 1957; thus were sacrificial from 2 months after the AFB was introduced. Step-up pistons (opinion) should at least be miked for wear (I am lazy, I just replace them automatically) at each rebuild and replaced if worn. The pistons come in the better rebuilding kits.

 

I will grant that 425 AFB's don't grow on trees, but 401 AFB's are relatively plentiful, and can fairly easily be re-calibrated to 425 specifications.

 

Jon

[NTX5467]

Thanks for that information, CarbKing.  On the surface, I would have suspected more differences between the "Cruise" and "Power" sections of the Buick primary metering rods.  My other question, related to that would be, with what size main jets?  MIght the wear on the power pistons be somewhat compensated for by using different springs under the power pistons( supplied in the tuning kit)?

 

In the Chevrolet Performance Handbook which Petersen published in about 1962, it mentioned filing the counterweights on the AFB air valves to get them to open quicker.  But once weight was removed, it would be hard to put it back on, usually, then trying again to hit the right combination of weight and shape for best results.  I suspect it was an art to remove weight from the correct part of the counterweight to get the desired results, not unlike where to remove weight from on a crankshaft counterweight in balancing a motor.

 

On the other hand, the OEM AFB which was on my '67 Chrysler 383 had no air valve above the secondary throttle plates.  A full "mechanical secondary OEM carb".  With the smaller sizing, I could hit WOT from idle with no hesitation, but after smoothing the casting flash on the outer venturis and throttle bores, doing that would cause a slight bog instead, which I took to mean I had increased the air flow just a bit.  Although that is not my normal driving style, then or now.

 

NTX5467

 

 

[carbking]

Willis - I have never been an advocate of filing weights (nor of soldering lead onto the weights). Carter offered a sufficient selection if one did one's homework.

 

A good friend on another forum has a suggestion in his signature block of "Wag more, bark less".

 

To complement ???  the Peterson comment, there was an article in a well-known automotive magazine which advocated replacing the vacuum piston springs in the Chevrolet 283 dual quad carbs with those from PaperMate pens.

 

Articles were written, published, magazines were sold, money was made, and the articles were read. (wag, wag, wag  )

 

Jon

Edited January 9 by carbking (see edit history)

[NTX5467]

PaperMate pen?  I guess that whatever could be had to work, back then, must have worked.  

 

Seems like that section on changing the shape/weight of the AFB secondary air valve counterweights had some pictures, before and after?  Enthusiasts, in general back then, did not have access to many "factory" or "supplier" information we came to discover later on, by observation.  Back when carburetors (at least in the JCWhitney catalog!) mentioned "Square Inches of Venturi

Area" as a gauge for more or less ultimate air flow, in a time before carb CFM was mentioned.  With the ultimate AFB size being that of the Chry 413 2x4bbl motor, IIRC.  Things were definitely more isolated and "shadetree" back then.

 

In those earlier 1960s days, having a friend at the dealership parts dept AND a larger salvage yard could be a "hot rodder's best friends".

 

Enjoy!

NTX5467

[RivNut]

I had an acquaintance, won't call him a friend, who had a salvage yard and in it he had a 63 Riviera with an AFB carb on it.  The Rochester 4GC on my car was beginning to leak. I asked if i could borrow the AFB while I got my Rochester rebuilt.  That was fine with him.  It took a while to get the 4GC rebuilt.  As I was driving by his place later, I noticed it was closed. A few inquiries and I found out he was in prison. The Feds confiscated everything he had.  I wound up with a good AFB and a rebuilt 4GC. Sold the 4GC and walked away with $$ in my pocket and a smile on my face. The car ran fine on the AFB for a long time before I rebuilt it. It still has the AFB on it now.

[carbking]

4 hours ago, NTX5467 said:

Back when carburetors (at least in the JCWhitney catalog!) mentioned "Square Inches of Venturi Area" as a gauge for more or less ultimate air flow, in a time before carb CFM was mentioned.  With the ultimate AFB size being that of the Chry 413 2x4bbl motor, IIRC.  Things were definitely more isolated and "shadetree" back then.

NTX5467

You might find the following links helpful:

 

WCFB flow ratings

 

Carter AFB flow ratings

 

Published carb CFM ratings have actually been around since the 1930's by both Stromberg and Zenith.

 

Jon

Edited January 9 by carbking (see edit history)

[NTX5467]

Thanks, Jon, for those links!

 

On the GTO 4-spd AFBs, might their flow ratings have been (without the dummy hot idle compensator) equal to or a little bit greater than their 3x2bbl set-up, on a better-flowing intake manifold?

 

Take care,

NTX5467

[Jim Cannon]

I am rejoining this discussion late...

 

For a "modern improvement", how about throttle body EFI?

 

It is hard to accelerate our massive cars without using a lot of fuel, and hard to pull it up a hill, but it seems to me that EFI could help you do it for the least amount of fuel possible. There will be no fuel percolation when you shut down the hot engine. No choke to stick open or stick closed.

 

I have seen EFI kits now that are more aimed at DYI installation.

 

I'll bet a few of you guys have done it on a nailhead???

[NTX5467]

TBI EFI is a possibility, but one which is not financially-viable from a fuel economy increase alone.  One of our chapter members did an "Affordable EFI" kits on his '50s straight 8 using a "DIY" tubular intake manifold.  I like that unit as it uses the GM ECM and custom-built PROMs to run it.  He later switched to an upgrade ECM which also does spark timing and such.  Initially, he noted about a 1.5mpg increase in highway mileage.

 

In the BCA Post-War forum, a few years ago I was conversing with a many who had one of the earlier self-learning kits put on the 430 in his Electra.  Unfortunately, something did not work out right and his highway mpg went from the high-teens to 9mph.  Never did find out if he ever got it figured out or it got better on its own.

 

All of those self-learning kits will require a particular style of distributor, too.  Not in the kits, but needed.  Holley came out with some 2bbl carb replacement kits, too.  Also one model which is "spreadbore" QJet style.

 

As time progresses, it seems that Holley's offerings get a bit more advanced and easier to install.  There is also a "fuel sump" which Edelbrock came out with so the factory pump pumps fuel into it, but the sump has the needed high-pressure pump to supply the EFI unit.  That's about another $300.00USD or so, but could also be a good deal if there is room under the hood for it.  Holley might have one, too?

 

Lots of YouTube videos to watch on installation and such!

 

Take care,

NTX5467

[XframeFX]

11 hours ago, Jim Cannon said:

For a "modern improvement", how about throttle body EFI?

The Carburetor has been defined as a 2-Circuit (Idle/Power) STATIC device in a DYNAMIC environment. A good argument for some sort of EFI if a clean install. But it ends there for me.

 

1) Processor control is required for EFI, ignition, drivetrain, HVAC, electrical system and CAN Bus between modules in modern vehicles. This requires built-in redundancy and the ability to "Throw Codes", a must with such complexity. Even just EFI, will stick with the KISS principle, thank-you.

2) My Riviera has GM (and Carter)  Engineering which if maintained or restored should have my ride running well.

3) All those EFI Kits are still too dear for the amount of mileage I Log. Can't justify.

4) I'm DONE with major expenses on my project

5) Desire to keep original configuration but to "tweak" to my satisfaction. Only Bosch Sparkplugs/wires. MSD Coil and AC/Delco 12SI Alternator are non-original. Breaker points remain although triggers a $9 TFI wrecking yard Module.

6) Nailheads are not high RPM "Screamers". So, no need for aftermarket induction and ignition upgrades that target those higher RPM capabilities. Plug-n-Play is no fun, it's NOT me!

7) I have $400 cash investment in my clunky original AFB. Not ready to mount it on a pedestal and set it on fire.

 

I consider myself lucky in that the Nailhead AFB is more desirable than a Nailhead 4GC. The AFB lives on as an E-Clone, not the 4GC. So, must be good.

 

Performing adjustments as part of Measuring, Analyzing, Tuning, tweaking is more cost effective. Read new sparkplugs for operating mode after logging hwy miles with minimal idling. Use a vacuum gauge, Pico-Scope, WB Gas Analyzer. Always room for improvement in the tuning department.

 

EFI not even on-the-radar. But a Twin Turbine to Variable Pitch ST400 swap has been on the back burner the whole 43 years I have my Riviera. Now THAT would be an improvement! Yes, I picked up a core ST400 shortly after acquiring my Riv about 1979. The swap will be a major expense and that is a problem. Should've done it before retirement.

 

 

 

[EmTee]

@NC-car-guy recently put TBI on his '57 364.  He's happy with it.  I think he got it from the same place as @Ben Bruce aka First Born.

[NC-car-guy]

15 minutes ago, EmTee said:

@NC-car-guy recently put TBI on his '57 364.  He's happy with it.  I think he got it from the same place as @Ben Bruce aka First Born.

I did put the Affordable Fuel Injection unit on my 364.  If you're going to drive it significant miles, worth it!  No worries about non-Ethanol fuel stops, cold starts, etc.   If it's not a driver, may not be worth the cost.

[Ben Bruce aka First Born]

"You can lead a horse to water but you can't make him drink"  comes to mind.

 

 As far as affordability,  most [ all? ] of us can't justify the cost of an old car. So why not just drive a newer one and be done.  Leave a little more time for watching mind numbing television?

 

  Like most things, to each his own.  

 

  Cost?  So far , at TODAY'S cost, mine is at about $0.04 per mile.  Like Willis said,  about 1.5 mpg better. Although at the time of installation, I had not driven the car enough to have a good base mpg.  Maybe 3000 mi.  The drive/trip to WA state this past summer netted better than 17 mpg round trip. PULLING AN 1100 LB. TEARDROP.  A trip to east TX a couple months back, about 370 miles round trip, showed 19.8.   WITH NARY A PROBLEM with the fuel system.   Only running problem, again , self induced, was an electrical one.  Fifteen years ago I MADE my own battery cables.  Heavy , for the then six volt. Changed to twelve.    I know, sacrilege, right?    Positive corroded  inside the  hardware.  New cable fixed.

 

 I do miss  [ 😁 ]  fighting the percolation. 

 

  Ben

Edited January 11 by Ben Bruce aka First Born (see edit history)

[telriv]

Ben,

 

That starter still working OK for you.

 

Tom T.

[gungeey]

Frank, why not get a 63 2 barrel intake manifold and 2GC carburetor. 

 

That's what many did in the early 70's. 

 

 

[XframeFX]

On 5/22/2017 at 5:17 AM, OldGerman said:

Do you know any modern spread bore carburetor, with the correct flow size, matching the Riviera intake manifold, the linkage system and the original small diameter Riviera Air Cleaner snorkel (plug and play) ?

 

4 hours ago, gungeey said:

Frank, why not get a 63 2 barrel intake manifold and 2GC carburetor.

 

16 hours ago, XframeFX said:

Plug-n-Play is no fun, it's NOT me!

Back to the original post topic - Frank, get a load of this Youtube Clip, over an hour long but blogger "Thunderhead289" has shorter lawn mower carburetor clips on his Youtube channel. Very Cool. Dude relates to more what I do, experimenter/inventor/tweaker. NO PLUG 'N PLAY!

 

[NTX5467]

What ever keeps you busy and happy!

 

On my side of things, I'm past the "Design it" phase and know that many suppliers have done better things to refine than I ever could, although any FI system will need some tweaking for the individual vehicle/engine combination.  

 

I'll admit that I don't have the intimate knowledge of Carter Carburetors that @carbking has, which I fully respect, but I've had an AVS on a car since about 1975, so I'm not afraid of them and the OEM ones seem to be even with the '67 OEM AFB that I have had since 1981.  As much as I like the Carter TQuad, the aftermarket version I got new did not live up to its billing, to me.  So, I'm not afraid of a new Edelbrock AVS2, although matching OEM metering characteristics can be in the mix.  

 

I'm not afraid of an aftermarket EFI kit, but I know some are better than others.  I've been pleased with the results @Ben Bruce aka First Born has had and that might well be the one I'd chose, if so motivated.  I do have one of the much-earlier Holley EFI 2bbl kits, when you had to build your own harnesses out of what was supplied AND get the computer to run things at WOT . . . still in the box.  I bought it for a vehicle which came with a factory ignition computer on it.

 

A TBI EFI and a carb do the same thing, mix air and fuel.  Just that the EFI will do it more accurately and compensate for lots of things that carburetors do that we might not like.  Which is good!  So the newer AVS2 with the annular discharge primary venturis would be my pick, closely-followed by the Street Demon TQuad clone, as to carburetors.  I have learned to tweak the electric chokes, over time.  Just as I tweaked the OEM divorced chokes on every carburetor I've had, to get it to act more like I wanted it to (get to "more open" sooner, being at base idle within three blocks in cold weather).  Which also included NGK V-Power plugs for a better burn, with the later NGK Iridiums coming later.

 

When I upgraded the Stromberg WWC 2bbl on our '66 Chrysler 383 to the newer OEM Holley 2210, as a pure bolt-on situation (other than the fuel line), I immediately noticed better throttle response and the fuel economy went up too.  Like 20mpg @ 55mph, which the OEM Stromberg never did, although it ran well for the time.

 

As much as I fully respect the engineering which went into the older vehicles, I ALSO know that some modern versions of earlier components are better than the original ones, back then, as to performance in normal driving conditions.

 

Considering how I have been able to finesse settings and equipment choices, for improved performance that makes me proud of what I did, I often wondered why the OEMs did not do similar things, all things considered?  Of course, I know there are other operating areas they had to "hit", too, which might be why they chose something more mediocre, by comparison.

 

For many years, I've wondered how much better older engines might run with a dose of modern technology.  Electronic ignition, EFI, a dose of modern camshaft tech, and 8-speed automatics.  Controlled by computers that optimize everything for best performance and results.  Which is what @Ben Bruce aka First Born is doing, whether he intended to or not.  I'm glad he's had the achievements he has accomplished!

 

I know we all have our own sensitivities to these things, which I fully respect and understand.  These are my own experiences and orientations.  It's been a "learning curve", for sure, spanning many decades.  I've had fun and learned a lot.  To me, that's important!

 

Y'all enjoy!

NTX5467

Edited January 11 by NTX5467 (see edit history)

[NTX5467]

Now, here's what I might do with a first-gen Riviera.  The carb would come off and be put in a safe place.  Perhaps even the intake manifold, too, opting for a later-model NailHead 4bbl.  As to the carburetor, if a spreadbore, then a Street Demon and matching the metering calibrations to a Buick 430 QJ, as close as possible.  If using an AVS2, then modifying the intake for the larger primaries, with an appropriate thick OEM-style GM base gasket.

 

Ignition?  Something drop-in, electronic conversion kit, with a faster mechanical advance and adding vac advance just to the edge of clattering on mile/heavier acceleration.  Magnetic suppression resistance plug wires leading to NGK V-Power or Iridium plugs for a better "POW" when they fire.  Sorry, my only experience with Bosch plugs was in the 1976 time frame and they were worse than the Champions I was using back then, although one friend put Bosch plugs in all of his turne-ups back then.  Just my experience.

 

Transmission?  An internally-beefed THM200-4R automatic (as seemed to be popular with other Riviera owners 15 years ago).  A bit better low gear, plus OD, PLUS less power consumption, so more power gets to the wheels with less fuel needed.  If the stock gearing and tire size was maintained, that might require EFI for best lower-speed response.  Otherwise, calibrated so OD happens past 55mph, with the kickdown linkage set to allow easy part-throttle downshifts and a bit higher min-throttle upshifts, for more acceleration with less throttle input.

 

Maybe replace the A-6 a/c compressor with a Denso item or a full Sanden conversion.  With a parallel flow condenser, too, for R-134a use.  Adjusting the POA to match.

 

Then, to the chassis . . . .

First place to look for better shocks would be KONI, then possibly KYB.  Add a rear sway bar, hopefully from an OEM application.  Some good radials with the correct (or close to it) whitewall width.  32psi frt/30psi rr, on the normal wheels.  Sorry, not a fan of Bilsteins.

 

Better brake linings than OEM, for better stopping under intense situations.

 

Everything in my orientation of "incognito upgrades" that can increase drivability and performance without getting away from the orig orientations of the car.  Quiet exhaust, too.  Sharp throttle response generally makes me happy, using less throttle to make things happen.

 

Reading the old road tests of 1963-64 Rivieras indicated they were more in the "refined performance" orientation, which I would hope to build upon with my proposed upgrades, if I had one of those cars.

 

Or perhaps I might just do the ignition system and chassis upgrades and call it good?

 

Just some thoughts,

NTX5467

[Aaron65]

I'm using a 650 AVS2 on my '63 right now. I bought the Dynaflow "kickdown" adapter from Centerville and wired up the electric choke to a switched fuse. After driving it around with my Innovate wideband (I only install it for carb tuning) I ended up leaning it out one step on cruise and power (using the Edelbrock owners guide) and richening up the idle circuit. Usually, I reduce the size of the top idle bleed on the primary cluster by using a ball bearing to close it up a little and opening it back up to size with a pin drill. It runs pretty well, although I don't know if it's worth the extra money for an AVS2; I've had decent luck with the regular AFB-style Edelbrock in other applications.

 

I typically like running the original Carter (or whatever the car comes with), but I went through the AFB that was on the car about five times, and it was both lean all around and inconsistent in behavior. There are some times when you just have to take advantage of a new part that works reasonably well for what you're doing with the car, and that's when I go with the Edelbrocks. Two of my cars have them and the rest use factory carbs.