i have a 1968 mustang and it has a holly 600 vacuum secondary carb on it with a edelbrock performer intake on a 302. my dads buddy has a 502 shevy in his 1948 ford business mans coupe. he had a jetted up 750 holly on it and it was a dog, it always ran rich and had not the power he should have had. he traded the 750 fer a 650 edelbrock thunder AVS and it totally woke the car up, now it hauls. my dad has the same car with a 350 chev, same intake as me and a GMPP ZZ4 cam in it. he has the 600 edelbrock on his. my question in is my engine over carburated? would it be snappier if i had like and edelbrock 500 on mine. i have 3.73 gears and a c4. remember im lookin for street performance

 

As you noted, the cam along with the cubes makes a diff. 600 seems high unless your 302 is really radical. Give the 500 a shot...

 

ya its stock with the intake and a pertronix ignitor conversion and dual exhaust

maybe a 500 cfm twobarrel, throttle response out the ***

 

Ive got a stock 289 with a 600cfm holley. Works just fine.

 

To calculate the correct carburetor size, engine displacement (in cubic inches), maximum engine speed (RPM) and volumetric efficency are the determining factors. The engine displacement is the maximum number of cubic inches of air that can flow through the engine during two revolutions. Remember that these rules apply to four stroke engines. Cylinder heads probably have the greatest impact on volumetric efficiency. The better the heads breathe, the higher the volumetric efficiency factor. The volumetric efficiency factor for stock to mild engines with unmodified heads should be around 80%, high performance street / strip engines should be around 85% to 90%. A volumetric efficiency factor of 100% is theoretical and most engines do not even come close to this mark.
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This calculator converts half of the engine size in cubic inches to cubic feet, multiplied by the maximum RPM, then multiplied by the volumetric efficency percentage. The resulting formula would then be:

cfm = ((((displacement / 2) / (1728)) * max_rpm) * volumetric_efficiency)



*copied/pasted from a formula site

 

i keep getting 5000 something for cfms, using that formula.

 

Try using this: http://www.4secondsflat.com/Carb_CFM_Calculator.html

 

You may want to try going smaller. The stock Cleveland with a Ford 4300 carb is I believe 610cfm.

Maybe Soaring could tell ya what the CFM of the 4100 is. I think the 4100 was stock on those anyway. Please correct me if that isn't it.

 

Nice Site, THanks!!!

 

Yup, my bad. "12 to the 3rd power" copies and pastes as 123. I did the math and fixed it. The calculator IS easier, but the site I was looking at had tons of them and Iit was too hard to find it in the list. I like the formulas because you can see how they get to the result.