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I'm building a 302 for my sister-in-law's 68 coupe while she's in Florida this next week. It is going to be 9.0:1 compression with stock 302 (circa 1978) heads. I will be running the Edelbrock Performer intake, cam, and carb (not the Performer RPM). Should I use the 500 cfm or 600 cfm performer carb? Thanks.
 

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600 will work, but 500 will work better. Better throttle response, better milage... and you won't notice (if noticeable at all) any power difference until you go past 5000 rpm which, I suspect, won't happen too often.

- Gord
 

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500
 

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If the 600 has vacuum secondaries, it'll work fine but as already mentioned, the 500 would be better for low end on a near stock engine. This is why I chose a 525 CFM Road Deamon over the 600. I don't plan on pushing more than 300 HP with the '65 Garage Shelf.

Regards,

Dean T
 

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Personally, I'd put the 1406 (600 cfm) on it. I have the exact same combo on my daughter's 302 (Performer intake, cam and carb). I jetted the 1406 up a tad, as it comes pretty lean out of the box.
Totally agree go 600, get on the dyno for a couple of hours set it and enjoy.

Jon
 

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Edelbrock used to have some great formulas for calculating req'd cfm. Check www.edelbrock.com. I think it'll calculate out to around 500 textbook.

I've got a bone stock 289 with the Performer Intake and a 1405 carb. I had to put bigger metering rods (make it leaner) by 2 steps on their calibration chart. It runs great, but I've never tried the 500 so can't compare.
 

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I know the formula that Holley developed about 100 years ago:

CID x RPM x V.E. / 3456 = CFM

(V.E. = volumetric efficiency)

This formula will give a stock engine adequate performance.

IMHO, this formula is only a starting point to determine carb size for peak performance. Many factors will allow for more cfm than the formula spits out.
 

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Ford ran a 600 stock on most 390's. For most street driving and a stock engine as you indicate a 500 should be fine, bigger is not always better.
 

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i run a 500 on my setup, and even with the 3.55 gears and running through the rpm's very fast it runs great and never seems to feel as though it needs more . i think it ran better than when i had a 600 on it in the past. it has some pretty good response.

i was going down a semi windy road the other day at about 35 in third and i downshifted into second and mashed on it and the tires broke loose a little bit and i got a little sideways ,i nearly shat myself lol yeap, il stick with the 500.

unless you plan on running the motor in the 5500 -6000 rpm range often, i cant see why YOUD NEED a 600. although a 600 will work, ive used one before
 
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