69 383 A-body Dyno results

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ls23h

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I’m in the home stretch to finally getting my GTS back on the street after way too many years apart.
The engine is a matching numbers .030 over with KB pistons, 9.5 compression, stock crank, 301 intake, Mr. Sixpack cam, dual point. The heads are the original 906 with stock valves and mild blending by Dwayne Porter. Big block A body exhaust manifolds will reduce the numbers some.
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sabre67 said:
duration and lift spec? please and thankyou
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Unfortunately, Bob Karakashian (Mr sixpack) does not publish the specs. His Engle cam is designed for running pure stock with exhaust manifolds. I was comfortable not knowing the specs, and purchased it based on his reputation and the performance of his cars.
 
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ls23h said:
69 440 4 speed AVS 4617s
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Wow, there's a lot of room for improvement there. Those carburetors were all notoriously small and lean. So those are some really good numbers considering.
 
66fs said:
750 cfm and not so lean.
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No sir. It's not. It has "around" 630 CFM and that's about it. None of the factory AFB or AVS carburetors were as big as 750.
 
ls23h said:
I’m in the home stretch to finally getting my GTS back on the street after way too many years apart.
The engine is a matching numbers .030 over with KB pistons, 9.5 compression, stock crank, 301 intake, Mr. Sixpack cam, dual point. The heads are the original 906 with stock valves and mild blending by Dwayne Porter. Big block A body exhaust manifolds will reduce the numbers some.
View attachment 1716103271
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Do you mind posting the correction factor, BSFC and total fuel used.
 
66fs said:
I don't think so. Front blades are the same as secondary blades on later HP 440's 68-71? Same on Marine carbs.
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What I am saying is, while some of them were rated at 750CFM, none of them flow that much. You have to remember, Carter had a different means by which they measured CFM, so it's not comparable to "everyone else" and always ends up on the low side in comparison. I get what you're saying and I agree, that's what "they said" some of them flow, but it's just not the real numbers. That's why when the old Holley 3310 750 was swapped on, they picked up every single time.
 
RustyRatRod said:
What I am saying is, while some of them were rated at 750CFM, none of them flow that much. You have to remember, Carter had a different means by which they measured CFM, so it's not comparable to "everyone else" and always ends up on the low side in comparison. I get what you're saying and I agree, that's what "they said" some of them flow, but it's just not the real numbers. That's why when the old Holley 3310 750 was swapped on, they picked up every single time.
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How did Carter measure CFM differently?? I have never heard that. Not that I doubt you, just never heard that before.
 
Rat Bastid said:
How did Carter measure CFM differently?? I have never heard that. Not that I doubt you, just never heard that before.
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Yes sir. They surely did. They measured using wet flow somehow. Everybody else seems to have used dry flow. It's fairly well documented......at least in all the OLD hot rod rags of the day.
 
The 750 Chrys fitted AVS carbs are 750 cfm, probably more.....
In my 77 catalog, there are 6000 series AVS carbs [ 6433 to 6437 ], listed as 630 cfm. The 9000 series & Comp Series AFBs are listed at 625cfm. Same pri & sec bore sizes, same pri venturi. The AVS does not have a sec venturi or booster or vel valve to impede flow so the reasonable assumption is that the extra 5 cfm [ probably conservative, too ] comes from the better flow of the uncluttered secs. Yes, AVS sec has an air valve, but it is straight, not bent like the AFB vel valve.

When you compare the Holley 4779 [ 750 cfm ] & 4780 [800cfm ] carbs with the above, it re-inforces the 750 rating for the Carter carbs.
Each of the 3 carbs has 1 11/16" t/bores. Sec bore of the AVS is the same at 1 11/16" as it has no venturi, just a plain bore. The pri vent is 1 7/16".

4779 pri & sec vent are 1 3/8". 4780 Pri & sec vents are 1 3/8" & 1 7/16".
 
Thanks for all the replies. I started this project when I lived in NY (40 miles from LVD) with the intent to race it some in pure stock. Fortunately we escaped NY and moved to Amelia Island Florida In ‘21. No tracks nearby so I changed direction with piston and compression selection for a 9.5 KB cruiser. I’m very pleased with the result.
 
RustyRatRod said:
No sir. It's not. It has "around" 630 CFM and that's about it. None of the factory AFB or AVS carburetors were as big as 750.
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Not sure what you are thinking of. Most original AVS carbs were 625-630 with the small primary blades. They were used on 340's, 383's, and low performance 440's. Max wedge AFB's I believe were about 750 cfm as well as 67 HP 440's using the larger blades as in later Competition Carters rated at 750 cfm. Also the HP 440 AVS's I mentioned earlier. I don't want to nit pick or talk about different rating systems. But I do know these carbs have the larger primary blades.

Original 4617sa AVS carb

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Original 440 low performance 4966s carb

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