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1963 401 Carb size???


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Nope - dyno results have their place, but not overly useful for street use.

 

As far as ET is concerned, we had a lot of Buick 455 owners 40 years ago that were extremely surprised when they found their 455's were actually quicker with the 850 CFM carbs than with the 1000 CFM carbs on the drag strip. We also had quite a few that found no discernible difference ON THE STREET from the 800 CFM to the 850 CFM; and the 1000 CFM were actually slower on the street.

 

Bigger is not always better.

 

The old saw about multiple carburetors coming in the mid-1950's because there was no carburetor sufficiently large is basically hog-wash. This is why I posted the fact that Holley had a production 600 CFM 2-barrel carburetor in 1929. Since someone will remember that 1 and 2 barrel carbs were tested on a different scale than 4-barrels, I also posted the 600 was on the 4-barrel scale. On the 2-barrel scale, this carb would have flowed more than 800 CFM. Significantly large carburetors for street use were available.

 

The Buick engineers were certainly aware of what was available, and chose NOT to use the larger carburetors on production vehicles.

 

Dyno results are quite useful for trailered racecars.

 

Today, because of better design cylinder heads, computer-designed camshafts, and better exhaust scavaging, more CFM may be utilized on pure race cars than 40 years ago. But street performance is more about venturii air velocity at all RPM's than wide-open throttle only.

 

Jon.

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2 hours ago, nailhead matt said:

there was no afb larger than the what they used during those years the nailhead was made.  hence they jumped on the qjet, and the qjet performs significantly better.  not because of the carb or the intake, but simply because it was bigger than the afb.    not as good as the dual quad, however.  

 

Matt - with no offense meant, Carter AFB 3636s, released in 1963 for the Pontiac 421 flowed 939 CFM when tested on the 4-barrel scale, and 1128 CFM when tested on the 2-barrel scale. Somewhere, I have the actual Carter flow test.

 

In addition to the 939, Carter made several 750 CFM AFB carbs. Even Chevrolet had one, Carter part number 3593s. Buick chose NOT to use the larger carbs on their production street engines. Pontiac and Chrysler both had 700 and 750 CFM AFB carbs.

 

The companies jumped on the Q-Jet, not because it was larger, but because of the higher venturii velocity for street use with the smaller primaries.

 

Jon.

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23 minutes ago, carbking said:

Nope - dyno results have their place, but not overly useful for street use.

 

As far as ET is concerned, we had a lot of Buick 455 owners 40 years ago that were extremely surprised when they found their 455's were actually quicker with the 850 CFM carbs than with the 1000 CFM carbs on the drag strip. We also had quite a few that found no discernible difference ON THE STREET from the 800 CFM to the 850 CFM; and the 1000 CFM were actually slower on the street.

 

Bigger is not always better.

 

The old saw about multiple carburetors coming in the mid-1950's because there was no carburetor sufficiently large is basically hog-wash. This is why I posted the fact that Holley had a production 600 CFM 2-barrel carburetor in 1929. Since someone will remember that 1 and 2 barrel carbs were tested on a different scale than 4-barrels, I also posted the 600 was on the 4-barrel scale. On the 2-barrel scale, this carb would have flowed more than 800 CFM. Significantly large carburetors for street use were available.

 

The Buick engineers were certainly aware of what was available, and chose NOT to use the larger carburetors on production vehicles.

 

Dyno results are quite useful for trailered racecars.

 

Today, because of better design cylinder heads, computer-designed camshafts, and better exhaust scavaging, more CFM may be utilized on pure race cars than 40 years ago. But street performance is more about venturii air velocity at all RPM's than wide-open throttle only.

 

Jon.

ive built over 200 of these engines and run them in my daily drivers and experimented with most the different intakes and different carbs.  building strictly these engines is what i do for a living.  so yeah, bigger IS better with these.  its been prover again, and again, and again..    we also own quite a few factory experimental intakes.  i get that you have a lot of carberator experience, and maybe im wrong about the carb sizes available at the time.  regardless, youre turning the conversation into a direction that has nothing to do with this thread.  the guy asked what carb to run.  800+ is the ticket as a fact.  even on a 364

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31 minutes ago, carbking said:

 

Matt - with no offense meant, Carter AFB 3636s, released in 1963 for the Pontiac 421 flowed 939 CFM when tested on the 4-barrel scale, and 1128 CFM when tested on the 2-barrel scale. Somewhere, I have the actual Carter flow test.

 

In addition to the 939, Carter made several 750 CFM AFB carbs. Even Chevrolet had one, Carter part number 3593s. Buick chose NOT to use the larger carbs on their production street engines. Pontiac and Chrysler both had 700 and 750 CFM AFB carbs.

 

The companies jumped on the Q-Jet, not because it was larger, but because of the higher venturii velocity for street use with the smaller primaries.

 

Jon.

by the way.  theres no 455  buick in 63.  its not even the same engine family.  you might as well be comparing a chevy

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No where that I read does anyone claim that a 63 had 455.  There is a 455 mentioned but no reference to 1963. 

 

All sentences should begin with a capital. When using a contraction for there is, there needs to be an apostrophe between the e and the s; there's not theres. All proper nouns should be capitalized - Buick, Chevy.  It makes reading a post so much easier when proper grammar and spelling are used.

Edited by RivNut (see edit history)
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10 minutes ago, RivNut said:

All sentences should begin with a capital. When using a contraction for there is, there needs to be an apostrophe between the e and the s; there's not theres. All proper nouns should be capitalized - Buick, Chevy.  It makes reading a post so much easier when proper grammar and spelling are used.

Sounds like a teacher?;)  My posts violate too if dictated into my smartphone instead of keying in.

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19 minutes ago, RivNut said:

No where that I read does anyone claim that a 63 had 455.  There is a 455 mentioned but no reference to 1963. 

 

All sentences should begin with a capital. When using a contraction for there is, there needs to be an apostrophe between the e and the s; there's not theres. All proper nouns should be capitalized - Buick, Chevy.  It makes reading a post so much easier when proper grammar and spelling are used.

comments like yours are typical of someone with nothing to offer the conversation.  i shared information that i've learned from experience.  information that i didn't have to share.  i build these engines for people all over the world. including the IVO dragster clone. instead, the topic has gone off in a direction thats irrelevant to the post,  making irrelevant comparisons, for the sake of trying to flex knowledge thats irrelevent to the point.  

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29 minutes ago, RivNut said:

No where that I read does anyone claim that a 63 had 455.  There is a 455 mentioned but no reference to 1963. 

 

All sentences should begin with a capital. When using a contraction for there is, there needs to be an apostrophe between the e and the s; there's not theres. All proper nouns should be capitalized - Buick, Chevy.  It makes reading a post so much easier when proper grammar and spelling are used.

or we can talk about 455 buicks and what carb came on a 63 pontiac, as if that has any relevance to this thread, nor does it have any relevance to the point i made.  i dont care.  i just think its comical, when someone tells me that dyno results dont mean anything

 

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Old Tank is correct.  I am a retired teacher. BSE and MAeD.  I just find it easier to communicate effectively with someone who uses grammar and punctuation properly. Never got beat up in high school.  I went to a high school where "hoods" were quickly expelled.  School was for learning, not trying to prove your worth by being the bully and trying to force your views on others.

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On 7/23/2019 at 8:52 PM, TerryH said:

Hey Guys looking for opinions on what size carb to put my 1963 Buick lesabre 401. It has a 2 bbl in it currently. I have found a 4bbl manifold and have ordered gaskets for the manifold and the carburetor including the heat shield. I also got the adapter for the tranny kickdown. I am looking for options on what size of carb to put safely on the all stock motor. Right now I'm looking between the Edelbrock AVS 2 650cfm and the next size up the AVS 2 800cfm.

Any help would be much appreciated.

Taking this thread back to it's original intent and setting some other things straight, here's the data on the 401 Buick engines. It is taken from the 1963 Buick Service manual for models 4400, 4600, 4700, and 4800.

 

20201023_143947.thumb.jpg.0b07ee042a6ad7e6c7b396db67669157.jpg

The Power Pack was the 401 engine that came in 1963 Riviera; 10.25:1 compression ratio, 4bbl carburetor, dual exhausts, 325 hp, 445 lb-ft of torque.  Standard engines 9.0:1 compression ratio, 2bbl car, single exhaust, 280 hp. And the export engine with its 265 hp 8.5:1 compression ratio. 

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15 minutes ago, RivNut said:

Taking this thread back to it's original intent and setting some other things straight, here's the data on the 401 Buick engines. It is taken from the 1963 Buick Service manual for models 4400, 4600, 4700, and 4800.

 

20201023_143947.thumb.jpg.0b07ee042a6ad7e6c7b396db67669157.jpg

The Power Pack was the 401 engine that came in 1963 Riviera; 10.25:1 compression ratio, 4bbl carburetor, dual exhausts, 325 hp, 445 lb-ft of torque.  Standard engines 9.0:1 compression ratio, 2bbl car, single exhaust, 280 hp. And the export engine with its 265 hp 8.5:1 compression ratio. 

theres no nailhead that came from the factory with 10 to 1 compression without a very rare export kit for the earlier nailheads.  all the 10.25 nailheads were only about 9.5.  the compression ratios were only advertised.  the highest compression stock nailhead, otherwise, was the 59 automatic 401, which was advertised as 10.5.... only ended up being 9.75, and i have factory documentation to prove it.

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27 minutes ago, RivNut said:

Taking this thread back to it's original intent and setting some other things straight, here's the data on the 401 Buick engines. It is taken from the 1963 Buick Service manual for models 4400, 4600, 4700, and 4800.

 

20201023_143947.thumb.jpg.0b07ee042a6ad7e6c7b396db67669157.jpg

The Power Pack was the 401 engine that came in 1963 Riviera; 10.25:1 compression ratio, 4bbl carburetor, dual exhausts, 325 hp, 445 lb-ft of torque.  Standard engines 9.0:1 compression ratio, 2bbl car, single exhaust, 280 hp. And the export engine with its 265 hp 8.5:1 compression ratio. 

to ACTUALLY take the thread to its  intent, and rather than post meaningless shop manual documents, and clown on other peoples lack of punctuation.  he asked whether to run a 650 avs2, or an 800 avs2.  the 800 will give close to 50hp gain on a stock engine.  that is a fact.   

 

Edited by nailhead matt (see edit history)
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I've been a bit intrigued by the "grossly over-sized" carb orientations, on basically stock engines.  Putting newer AFBs and such can be a bit problematic on Buicks due to some if their throttle hook-ups and such, PLUS the "heat tracks" in the intake manifolds (for which there are NO modern equivalents).  Match the carb throttle bore sizes to the holes in the manifold's carb mounting flange.  Past that . . . whatevere trips "passing gear BEST" for y'all.

 

NTX5467

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1 hour ago, NTX5467 said:

I've been a bit intrigued by the "grossly over-sized" carb orientations, on basically stock engines.  Putting newer AFBs and such can be a bit problematic on Buicks due to some if their throttle hook-ups and such, PLUS the "heat tracks" in the intake manifolds (for which there are NO modern equivalents).  Match the carb throttle bore sizes to the holes in the manifold's carb mounting flange.  Past that . . . whatevere trips "passing gear BEST" for y'all.

 

NTX5467

 

Willis - a number of facts which intrigue me:

 

(1) If one compares throttle bore/venturi size on Carter AFB's and the new "AFB"/"AVS" units, one finds:

   1-A  Carter rating 625 CFM, Edelbrock rating 650 CFM

   1-B  Carter rating 750 CFM, Edelbrock rating 800 CFM

 

This may be an example of the "new math" ;)

 

Taking these figures back to 1963:

 

Carter offered a 750 CFM (new math 800 CFM) which Buick engineers chose to NOT use on their production vehicles in 1963. If the 750/800 is so much superior to the 500/610/625 versions used by Buick on various engines in the early 1960's; one wonders WHY these were NOT used. My GUESS (not necessarily fact) would be that the Buick engineers were interested more in driveability than absolute power at wide open throttle. One can look at Carter 3529s (Buick number 1356948) that was tested by Buick, and rejected. The only examples of this carburetor were the six prototypes sent by Carter to Buick. There was no standard production.

 

As far as the OP's original question, I suggested the original carb, and still believe that is the best carb for basically stock street (not necessarily race) application - BUT THAT IS PROFESSIONAL OPINION, not necessarily fact. Others obviously have a different opinion. I guess if absolute power is the most important consideration, then maybe the larger carburetor could be used. All of us can learn from a respectful dialog.

 

The only reason I posted in this thread, other than the original carb suggestion, is a modification of history as to carburetor introduction dates, sizes, etc. As an automotive historian, I find this less than satisfactory. I believe we have an obligation to keep history separate from opinions.

 

As far as dyno tests go, in 60 years of playing with cars, have seen way too many tests that prove what the tester wished to prove. Dyno tests CAN be a useful tool, especially in designing/tuning race engines. As I do very little with racing these days (and then it would be vintage racing, not modern stuff), I have little need for dyno tests. Again, my professional opinion; others obviously have differing opinions.

 

Jon.

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1 hour ago, NTX5467 said:

I've been a bit intrigued by the "grossly over-sized" carb orientations, on basically stock engines.  Putting newer AFBs and such can be a bit problematic on Buicks due to some if their throttle hook-ups and such, PLUS the "heat tracks" in the intake manifolds (for which there are NO modern equivalents).  Match the carb throttle bore sizes to the holes in the manifold's carb mounting flange.  Past that . . . whatevere trips "passing gear BEST" for y'all.

 

NTX5467

its extremely easy to swap a larger late edelbrock or afb on a nailhead.  57 to 63 dynaflow engines require a kick down adaptor that we sell for 35 dollars that take 15 minutes to install and adjust.  theres many intake casting inconsistency variations, but most intakes require beveling of the edges for throttle plate clearance, or mod the top, remove the webbing, to connect the primary with secondary on each side, which adds probably 5hp by removing harsh 90 degree angles and increasing plentum volume.  you WANT to block the heat riser passage at the top of the intake at the very least with 7/16 set screws.  even better if you block off all heat at the intake gasket with special intake gaskets we sell.  it eliminates related heat soak and vapor lock issues  with the low boiling point of todays fuel.  my 401 can sit in the garage for week and fire up on the first turn as the fuel hasnt evaporated out of the bowl.  plus probably a 15hp gain with keeping the intake cooler.  fuel will still vaporize just fine, contingent upon good attomization, as the intake will still get 135+ degrees.

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31 minutes ago, carbking said:

 

Willis - a number of facts which intrigue me:

 

(1) If one compares throttle bore/venturi size on Carter AFB's and the new "AFB"/"AVS" units, one finds:

   1-A  Carter rating 625 CFM, Edelbrock rating 650 CFM

   1-B  Carter rating 750 CFM, Edelbrock rating 800 CFM

 

This may be an example of the "new math" ;)

 

Taking these figures back to 1963:

 

Carter offered a 750 CFM (new math 800 CFM) which Buick engineers chose to NOT use on their production vehicles in 1963. If the 750/800 is so much superior to the 500/610/625 versions used by Buick on various engines in the early 1960's; one wonders WHY these were NOT used. My GUESS (not necessarily fact) would be that the Buick engineers were interested more in driveability than absolute power at wide open throttle. One can look at Carter 3529s (Buick number 1356948) that was tested by Buick, and rejected. The only examples of this carburetor were the six prototypes sent by Carter to Buick. There was no standard production.

 

As far as the OP's original question, I suggested the original carb, and still believe that is the best carb for basically stock street (not necessarily race) application - BUT THAT IS PROFESSIONAL OPINION, not necessarily fact. Others obviously have a different opinion. I guess if absolute power is the most important consideration, then maybe the larger carburetor could be used. All of us can learn from a respectful dialog.

 

The only reason I posted in this thread, other than the original carb suggestion, is a modification of history as to carburetor introduction dates, sizes, etc. As an automotive historian, I find this less than satisfactory. I believe we have an obligation to keep history separate from opinions.

 

As far as dyno tests go, in 60 years of playing with cars, have seen way too many tests that prove what the tester wished to prove. Dyno tests CAN be a useful tool, especially in designing/tuning race engines. As I do very little with racing these days (and then it would be vintage racing, not modern stuff), I have little need for dyno tests. Again, my professional opinion; others obviously have differing opinions.

 

Jon.

100 bucks says youve never even had one of these engines before.  but yet you think your generic, irrelevent information outweighs my expertise over something i actually specialize strictly in.  its the definition of ignorance.  this forum is the blind leading the blind.  waste of my time

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Matt - as far as rebuilding one of the ENGINES, you are correct. I only rebuilt engines for myself, not for others.

 

As far as rebuilding, installing and tuning carburetors (in person), helping customers tune via telephone, changing to different carburetors for these engines; You are wrong, I have lots of experience with them.

 

So I guess your 100 bucks is a wash; you win the first half, and I win the second half.

 

Jon.

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17 minutes ago, carbking said:

Matt - as far as rebuilding one of the ENGINES, you are correct. I only rebuilt engines for myself, not for others.

 

As far as rebuilding, installing and tuning carburetors (in person), helping customers tune via telephone, changing to different carburetors for these engines; You are wrong, I have lots of experience with them.

 

So I guess your 100 bucks is a wash; you win the first half, and I win the second half.

 

Jon.

  its like me, giving my input on 455s because i specialize in nailheads.  they're both buick right?  that must mean all the same principles apply?  hell no.  thats how you look, spewing generic carb information, as if every engine thats a similar cubic inch, is the same.  some times you have to know enough to know when you DONT know.  buick also deliberately de-tuned their distributor curves as well. whats your point? does that mean its best (or perform its best) to leave it that way "because its stock?"  of course not.  the performancemodel (dual quad 425)  got a better curve and over 800 cfm as a performance model, despite the same camshaft

Edited by nailhead matt (see edit history)
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Obviously, we have some generational issues, here!  Back when CarbKing was doing his many things with Carter carbs, back then, the "data" he was learning was from "original knowledge" which FEW people outside of the specific OEM engineering groups had access to.  All highly-regarded engineering information.

 

It used to be that "bigger" was always better, but when it was determined that things like idle quality, throttle response and even fuel economy were highly-prized by many Buick owners, then Buick engineering had to give then what they wanted.  Especially IF the OEM might save a few dollars/vehicle doing it!

 

When looking  at what the OEMs were trying to do, back then, you HAVE to understand what they were up against.  THEN you see how you might approach the issue for best results.  MANY TIMES, the OEMs usually did a better job of solving the issues at a lower price, by observation.  Many of the middle-'50s+ design orientations had some good theories behind then, but it would not be until the 1980s when those concepts would be best-implemented, by observation.

 

Everybodies got their own baggage.  For many of OUR purposes, the "old baggage is best".

 

Enjoy!

NTX5467

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When new, the owners of these late 50's and early to mid 60's Buicks did not drive them like we do. They were family cars and daily drivers. Maybe every once in a while, perhaps when passing another car, a right foot may have gone to the floor. You wanted the car to start, run decently all the time (heat passage), be reliable, and deliver the gas mileage inherent with what you expected.  Today it seems that no one just drives there and back. You drive as fast and as hard as the guy next to you, whether it be a Chevy Volt or a Mustang. From what I read, it sounds like Matt is only concerned with WOT performance. Jon is telling us why the carb was designed in the first place.  One of the other forums has a subforum about where did you drive your car today. Some guys delight in driving 20 miles for coffee.  My mom and dad, with the 3 kids, took a vacation 3 years in a row 63, 64, and 65 in our 63 Wildcat from Kansas to Oregon to see mom's aging parents. Did not cross our minds how many CFMs the carb had, if the heat passage was blocked off.  All we cared about was that the a/c worked, the seats were comfortable, and we could cross the Continental Divide without loss of power or vapor lock.  Put what ever carb in your engine that gives you what you're looking for in your style of driving.  Could be that you'd be better off with a lower compression, more drivable, two barrel.  I drove a 55 Special while in high school. It got me to school and home, to Linda's house then to the movie or the swimmin' hole, or wherever.  I was much more in tune to Linda's specs than to what carburetor my car had.  I probably had a choice as to where to spend my time; under the hood of my car or under a blanket with....... 😘

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  • 3 weeks later...

Based off all the arguments here I took none of your advice and bought a Sniper EFI system to go on it lol! I had the opportunity to pick up a kit at a steal of a deal so what the heck I thought lets open a whole new can of warms!

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17 hours ago, TerryH said:

Based off all the arguments here I took none of your advice and bought a Sniper EFI system to go on it lol! I had the opportunity to pick up a kit at a steal of a deal so what the heck I thought lets open a whole new can of warms!

Did you also get the distributor and spark box to go with it ?  

 

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  • 3 weeks later...
On 12/4/2020 at 9:48 PM, RivNut said:

The original Carter AFB used on the 401 V8 was rated at 625 cfm by Carter.

 Installing a modern 650 such as the Edelbrock AVS2,  I may not gain power, but certainly won't lose any.  #1. My concern is the AVS2's throttle link ball location working with this throttle rod length/position for my Electro-cruise set up.  #2. The metal fab required to use the stock correct air cleaner.

 

I wish the OP all the best in his EFI conquest. 

 

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