carb question?

changing jets

insanemach1 said:

I was wondering if any of you guys know how far you can jet a carb up or down was looking at a few sets today but i have never messed witht he jets in a carb before me bieng a body man more than a bolt turner. Anyways I got a holley 750 double pumper and it is to much for my 302 atm. How far can i jet it down? could i take it to like a 550 or 650, I would like to keep from buying a 600 for i am gonna just drive it like it is this spring and gonna build another moter for this carb to go on. any advice would be great.

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Changing jets will not change the cfm, it will only affect your fuel mixture. Get a 600, especially with the auto. Jon

If you master the art of tuning a Holley, you could play with the jetting, power valve, accelerator pumps/squirters/accuator cams and air bleeds on that 750 to make it work on the 302, but the carb will always be too large with a low(flat, boggy response, etc) booster signal at anything under 4000 rpm.

The only time you'd actually want to run a carb that large on such a small motor is when you build the motor to make power way up high in RPMs. (8000+)
As was stated, get yourself a nice little 600, and spend some time tuning that one, instead. It'll be snappy at low end and will have plenty of airflow to supply most street 302s.

Edit: If you plan on building a 500 hp 302, then a 750 will work. Otherwise, if you build your 302 up somewhat, a 650 double pumper is probably as big as you'll want to use.
If you spend the money and buy a race demon carb, you can get away with running a larger cfm version, without losing low end response, because the demon design is similiar visually, but vastly superior functionally, to a stock holley unit.
One last thing, there are certain demon carbs available that have removable venturii sleeves, which do allow you to change the cfm value of the carb. Nice for future motor buildups, so you dont have to buy another carb when you increase the power output.