[Eastex Jr]

I have SBC 355 with edelbrock performer "6089" not 60899 heads which are 64cc, I have flat top pistons and I will be running comp cam 12-250-3 cam. Grind# XE284H-10.I plan on running a Edelbrock Airgap performer intake.And a Edelbrock AVS Carb either 650 cfm or 800 cfm. Edelbrock sugested a 800 cfm for my setup that just sounds to large to me.Ive heard i fall in between so just go larger to the 800.So with the set up i have what compression will i have and which carb out of the 2 do yall think would be best.

[41 kustom]

Edelbrock is a good choice. You can do a lot of tuning to it as you go to get the best performance. In the past I've went with too big a carb, big mistake . But like I say you can do a lot of setup with it, good luck.

[T-bucket23]

Originally Posted by Eastex Jr

I have SBC 355 with edelbrock performer "6089" not 60899 heads which are 64cc, I have flat top pistons and I will be running comp cam 12-250-3 cam. Grind# XE284H-10.I plan on running a Edelbrock Airgap performer intake.And a Edelbrock AVS Carb either 650 cfm or 800 cfm. Edelbrock sugested a 800 cfm for my setup that just sounds to large to me.Ive heard i fall in between so just go larger to the 800.So with the set up i have what compression will i have and which carb out of the 2 do yall think would be best.

650 should be more than you need

[my87Z]

i am personally not a fan of edelbrock carbs, but eveyone has their own opinion. i wouldn't use the 800cfm carb, you are gonig to loose lowerend throttle response with it, i'm sure they can be tuned quite a bit but the venturies will still be to large for the lowerend. i would go with the 650cfm. personally i would strongly suggest a Holley 650cfm vac secondary like this one.
http://www.summitracing.com/parts/HLY-0-80783C/

it has been on of the most used carbs around for over 30yrs, but it's just my suggestion, if you like eledbrock then go for their 650.

all CFM is really about is how many rpm's you are running. a big block could stand to use a 650cfm carb it weren't going to see over 4000rpm. with the cam you have you won't likely be going over say around 5800rpm and on a 350 for that rpm a 650 is all you will ever need.

as an example, i have a 385 that i turn up to 6500rpm that is making 550hp but since i still drive it on the street more than at the track, i have a tuned up 750cfm double pumper on it and it runs great, i have put a 850DP on it for about a 2 months and the only thing that did was make the car more inconsistant at the track.

[327NUT]

My 331" sbc had Edelbrock heads, Air Gap, Quick Fuel Tech. 650 vac. sec and a Comp XE262-10 cam.....ran VERY good in the chassis but never got on the street.....sold it to a guy that REALLY wanted it $$$$$$$$. The 650 will be just fine.

[techinspector1]

Originally Posted by Eastex Jr

I have SBC 355 with edelbrock performer "6089" not 60899 heads which are 64cc, I have flat top pistons and I will be running comp cam 12-250-3 cam. Grind# XE284H-10.I plan on running a Edelbrock Airgap performer intake.And a Edelbrock AVS Carb either 650 cfm or 800 cfm. Edelbrock sugested a 800 cfm for my setup that just sounds to large to me.Ive heard i fall in between so just go larger to the 800.So with the set up i have what compression will i have and which carb out of the 2 do yall think would be best.

Static compression ratio will be ~10.30:1 and that cam is a good match. I don't like the extreme energy grinds, but the duration and intake closing point are just right. Use the 800 carb, rebuilt part #1813, #8013 choke cable assembly, #1841 metering rod and jet kit. The cam closes the intake valve at 46 degrees ABDC, yielding a DCR of 8.46:1 on the KB calculator. Mount the carb on a Performer RPM intake manifold (not the Air Gap) and mount a 14" x 4" air filter on top. Use long-tube, tuned headers with 1 5/8" primary tubes.

Unlike in the past, I am having difficulty finding the throttle bore sizes to compare the 650 to the 800 carb. What I'm thinkin' is....the primary bores may be the same size on both carbs, with larger secondary bores on the 800, so the fuel mileage will be close with either one, provided you keep your foot out of the secondaries.