Carb size 454bbc
 

Spent hours on the internet researching and I’m still no closer to a decision.
New 454 crate motor with headers.
Currently running an Edelbrock AVS2 650cfm that was on my old motor,wondering if I should go bigger.
I’m going to stick with Edelbrock because I have a ton of rods, jests, springs for tuning but mostly because I have a performer RPM fuel pump and would have to replace it to run a Holley.
Choices I’m looking at: Performer 750 cfm and AVS2 800cfm , mainly considering the 800 because I like the AVS2 and that model doesn’t come in 750.
What’s your thoughts, do I need a bigger carb?

Re: Carb size 454bbc
 

How are you planning on using the 454?

Re: Carb size 454bbc
 

Summit has a good calculator. Street vs strip use will make a difference.

Re: Carb size 454bbc
 

I don’t run it on the strip, I drive it a lot and want to take advantage of available power without compromising streetability . 500 mi and first oil change so today I opened it up for the first time and seemed happier when it was being fed .

Re: Carb size 454bbc
 

For the most part GM put 750's on the early 454's and then in the mid 70's they went to 800 cfm. They were all Qjets. If you like the AVS carbs go with one of them. I wouldn't think twice on putting an 800 on a 454.

Re: Carb size 454bbc
 

Got a 650 on my mildly built 454, runs great, but with the 4 speed it rarely goes over 4k. It gets there pretty quick though. Pulls strong from about 1800 up until I shift. That is on my 68 gmc. My 69 GMC flatbed with just about the same build, I put a 750 on it because it will pulling heavier loads and has an automatic and may see a few more rpm just for fun. No headers on either one, both have cast iron manifolds with a single 3'' exhaust

Re: Carb size 454bbc
 

Does your 454 need a bigger carb? Going by the book, yes. 800AVS would be a good choice if it’s a typical mild street 454. That said if It’s my money being spent I’d stay with the 650. You might gain 20-30 horsepower at the very top end of the RPM scale (5000rpm+). Other than that, zero gain or difference, particularly at our high altitude.

Steve weim55 Colorado

Re: Carb size 454bbc
 

Update
Installed the AVS2 800 today and I couldn’t be happier. Stronger from A-Z , crisp and solid from off idle, mid and WOT. I was really worried about losing low end but it feels great all around, the motor even sounds smoother. Just wanted to update, I appreciate all the input.

Re: Carb size 454bbc
 

I have a 468 BBC with headers and a performance cam that dyno tested at 500hp. I am running an air gap Edlebrock intake and a holly 670 street avenger carb. Very steerable combo, with a nice reliable idle, and smooth acceleration thought out the range but when you decide you want to get after it, it definitely gets after it. I know you wanted to stick with Edelbrock so just threw the info out there so you might find an equivalent. Good Luck.