Just wanted to see if you anyone has advice on CFM's on Carbs. I have a choice between 2 Elderbrock performers one's a 600 CFM and the other is a 800 CFM. I'm kind of torn between the 2. Not sure if the 800 would bog on my engine. I'm running a 355 v8 with stock heads edlerbrock intake, headers, HEI Distributor, & Glass Packs with a 3:73 rear. I really wanted to get something which would give me more HP. I think I have 725 CFM Elderbrcok on it right now. So my thought was 600 CFN for saving gas and a 800 for more power. Now I saw somewhere that the quadra jets the chevy had in the Camaro's were 800 CFM stock. Is that true?

If someone could point me in the right direction that would be great.

Thanks,
Mark - Haverhill MA

 

up to 850 ... but that was the big block quads ...
if you do a real good job on the carb it will give great idle good gas milage and good power.
see the patern.
but if you put say 750 double pump, bad idle, terrible gas milage, maximum power.

you have the right idea but any carb still needs to be calibrated ( jetted, adjusted )
for your engine, and that is what makes the biggest difference on all aspects.

it's a diing art to be able to set up a carb due to fuel injection

 

^^agreed. I would run the 600. Now way the basicly stock motor would like the 800. I belive the 725 is to big. Ive had a simular combo to yours in almost every car/truck I ever owned. A bigger carb won't add power. It will only allow the engine to suck in more air. If the the carb is too small its like trying to breath through a straw. If its too big the air won't move fast enough through it making tuning a *****. Here is a calculator http://www.4secondsflat.com/Carb_CFM_Calculator.html . Keep the volumetric efficiency where it is. Most motors in good shape are in this neighborhood. Blower motors are usually the only ones at 100% or over. Don't forget to use ci.

 

Personally, I wouldn't go with smaller than a 650 on a 355. I think the stock default 83% VE on the above calculator (still just a best guess estimate) may be a little low, considering the engine has a better intake and exhaust to increase flow. A slightly bigger carb than calculated won't hurt performance as much as one too small would.

 

Little carbs mean low end power. Of course you don't want to go too small, but a 600 is just about perfect for a stock 350.

 

Why change?
Anyway, the 800 is to big. I am running a 400HP crate 350, Airgap intake, headers, and a 750 Double. My carb is to big, but I am getting a cam to handle it in a few weeks. I bought my carb to go with the 2.08 heads I have planned.

My car had a 625 Edelbrock, and ran better. Never had it on the track but it was nicer to drive and a hell of a lot easy to tune.

An 800 is simply to big for a stock motor, you wont like it.

 

Thanks for all your helps guys. I just wanted to make sure before I bought the worng one.

 

I almost did catch that. But if you don't know what you got. I would run the numbers on the front of the carb. I can't count how many times some one has popped there hood and said it was a 750 or something and I'm starring at the pn knowing damn well its a 600. 1405 600 cfm man choke, 1406 600 cfm elec. choke, 1407 750 cfm man choke, and 1411 750 elec. choke. The 800's are 1413 and 1413. No 725's listed. The pn is on the lower left corner of the carb.

 

so do you know what a holley 80423 is?
Says Holley all over the carb and on the base plate where 1405 should be it has 80423.
I was told it was a 750 buy the guy I trade with. But looking around it seems that it is an 850.

 

Here ya go. http://www.holley.com/data/TechServi...%20Listing.pdf Something is wrong with my adobe reader, it just makes my explorer quit working. I love the holley site though. I still have the books from back when I had to look for real.