I'd go with the 800 cfm, given the performance potential of your engine. What is the advertised compression ratio?

 

10:1

 

I'm really not a Edelbrock fan, but of those two I think either will be fine. 650 might shave off 4hp at redline, but it will be a much better street-mannered truck. I think too many people focus on the most HP and forget that on the street, we drive torque, throttle response, and MPG. And trust me... you'll never notice 4hp missing.

If you really want the most accurately metering carb on the planet, you get a Qjet. It's also one of the toughest to tune properly, but once dialed in, they are as close to EFI as you can get.

 

I'm also not an Edelbrock carb fan. Have a bud that had both the 650 and 800 AVS. 2 years of tuning with calibration kits....and they never ran right

Pulled off his BBC to drop on a Demon 850. 3 minutes after bolting it on, and slight tweaking the idle mix, it was doing 2 block long burnouts

The Edelbrocks just aren't set right out of the box for anything above and 8:1 sloppy smog motor

 

The other 2 brands i was eyeballing were quickfeul and aed

 

I've tried 2 brand new holley carbs and both had float issues so bad it had to be rebuilt and holley wouldn't honor their warranty just want to send parts to try and fix it myself. Not worth it

 

Holley, Quick Fuel, Demon, AED are all same company

 

Given that 383’s aren’t stock what does a stock bottom end exactly mean?

Bogie

 

 

Oh God another over cammed under headed and under pistoned 383, yikes!

Keep n mind that hypereutectic pistons disappear in a second when faced with detonation or preignition. You are well advised to keep the revs down and the octane up.

It really doesn’t need a huge carb and since it is a torque monster not a rev’er cause you just can’t take those pistons where that cam can go and besides the 195cc heads aren’t going to breath that well over a 383 so you don’t need to go crazy with a huge carb. A Holley 750 or Edelbrock 800 would be plenty if not too much.

Bogie

 

That's my motor with 195cc afr enforcer heads

 

I'm probably not going over 6000rpms in my application js

 

I had one of these vacuum secondary 750 CFM on a daily driver 383 in a '92 S10

Summit Racing SUM-M08750VS Summit Racing™ M2008 Series Carburetors | Summit Racing

I had the 600 CFM version on a 350 in the same truck. I put a gozillion miles on them with no trouble. I think I've been pretty fortunate with carburetors in general. I really haven't had any hassle with any of them beyond the usual learning curve stuff. I really like the AED on my big block G Body and have always been a fan of the Quadrajet.

From the specs on the engine (specifically the cam), I doubt I would run a stock torque converter. I realize this was a carburetor question but if the engine is coming out it's a good time to make a converter swap. If you have already looked into it disregard the mention.

 

I had one of these vacuum secondary 750 CFM on a daily driver 383 in a '92 S10

Summit Racing SUM-M08750VS Summit Racing™ M2008 Series Carburetors | Summit Racing

I had the 600 CFM version on a 350 in the same truck. I put a gozillion miles on them with no trouble. I think I've been pretty fortunate with carburetors in general. I really haven't had any hassle with any of them beyond the usual learning curve stuff. I really like the AED on my big block G Body and have always been a fan of the Quadrajet.

From the specs on the engine (specifically the cam), I doubt I would run a stock torque converter. I realize this was a carburetor question but if the engine is coming out it's a good time to make a converter swap. If you have already looked into it disregard the mention.

 

Were you trying to run the in-tank TBI fuel pump with those Holleys? If so, what pressure regulator were you using?

I have an 89 S10 with 383 built similar to yours. 10.3:1 with AFR 195 Eliminator (not Enforcer) heads and an Edelbrock Performer RPM intake (not air gap). My Cam is now a Comp XS274S (236/242) solid which is equivalent to their XE274H (230/236) hydraulic cam, both at 110LSA. So my cam is very similar to yours, but your roller cam will have a slight edge. However my heads are better.

On my light vehicle with a custom torque converter, I run a Quick Fuel SS-830 double pumper for instant throttle response. If yours is an automatic in a heavy truck with stock converter, you should be using at least a 750 CFM with vacuum secondaries on your 383. Vacuum secondaries are on demand and automatically adjust carburetor size for you!!

Good luck!

 

I can't remember but the other motor i had in it was carburetated with a regulator

 

My dads 383 is similar to yours; he has the (vac secondary) 800cfm AVS2 and loves it.
Mild word of caution though; you cannot easily convert a manual choke to an electric choke on specifically the AVS2. He goofed up the part number and order the manual choke. After much screwing around, he sold it and bought the elec.
His was a reman, and was very clean. I bought a calibration kit; never needed it tbh

 

My dads 383 is similar to yours; he has the 800cfm AVS2 and loves it.
Mild word of caution though; you cannot easily convert a manual choke to an electric choke on specifically the AVS2. He goofed up the part number and order the manual choke. After much screwing around, he sold it and bought the elec.
His was a reman, and was very clean. I bought a calibration kit; never needed it

 

Thanks for the advice everyone I'm probably going 750 performer carb from eldelbrock. 800 seems a lil much for my application

 

The AVS2 is a much improved carb over the performer which derives from the old Carter 1957 AFB which does not have an adjustable secondary air valve. The AVS2 derives from the newer but still old Carter AVS of 1966 which has an adjustable Secondary Air Valve hence the term AVS. This allow you to time the secondary tip in and the rate at which it comes on. The Performer AFB does not allow this it is what it is as it uses fixed counterweights where the AVS uses a spring with adjustable tension that is adjusted by a screw at the airhorn.

The Carter AVS became the Edelbrock Thunder. Initially the only change to the Carter design was attaching an Edelbrock stick on label. Later Edelbrock changed the primary booster to that of an annular style which makes for a more uniform mixture with greater sensitivity with changes in engine air flow demand then renamed it the AVS2. The AVS2 offers much better mixture mixing and control along with an adjustable secondary activation this a big advantage over the quite good venerable AFB Performer.

Bogie

 

I would like the avs2 but 800 is too big for my motor. I wish they had a 750 avs2

 

Why is an 800 to big? You bought a Blue Print 377 with a very big cam and high compression that develops over 400 horsepower as configured by its manufacturer. We commonly use 750’s on similarly configured 350’s while here your feeding a 9% bigger engine which shows that we pull max power from a 350 so configured at 6000 RPM with a 750 then a proportionally 9% larger engine would need a larger carb to peak power at 6000 revs and that would be a carb flowing 817 CFM.

Plus the AVS 2 brings a big connivence to the party that the AFB does not which is secondary adjustability.

Bogie

 

Thank you so much for clearing it up. I will definitely buy the 800 avs2

 

Are you aware of a couple things you might need for your avs.
Fuel pressure needs to be kept near 5 psi. You might need a regulator or lower rated fuel pump.
Fuel boiling in the bowls can be a problem. You might need a heat spacer between the carb and intake.

 

I got the regulator. Need to get a new pressure gauge for it. I'll get a heat spacer cuz I don't think I have that yet