i don't think anyone realizes that there is a new section yet .and by looking at the dates on the threads i don't think that the ssp guys used this much either .
i don't think anyone realizes that there is a new section yet .and by looking at the dates on the threads i don't think that the ssp guys used this much either .
haha true, didnt think about that. i hope this thread catches on tho, iv been looking for info on our my 85 motor and cant find much.
Pick the right size for one. I like using the calulation Pro Systems runs with. (CID*RPM/2820)*VE=CFM. They use 2820 instead of 3456 because the modern carbs have better booster technology that can make signal on miniscule vaccuum, so you can calculate for a slightly larger cfm than in years gone by, to reduce the top end restriction. The other thing to consider aside from the obvious, is that we usually calculate CFM based on maximum rpm and maximum VE, but max VE is at peak torque, not peak rpm, so VE is lower at peak rpm. That means that after peak torque, the increased rpm=more cfm needed, but decreased VE=less cfm needed. So when you calculate for peak rpm cfm needed based on the ve at peak rpm, you end up with an even smaller cfm rating than you think you need. When I calculate that way for my 302(heads, cam, some internals etc) it comes out to around 520cfm, assuming around 90% peak VE and about 80% VE at 6,000rpm. With a dual plane I'm running 570cfm and have excellent throttle response and power from low rpm all the way to peak, and shifting at 6k rpm the engine isn't falling flat. Under acceleration it actually has a peaky feel to it, pulling harder as the engine gets up to 6k, so the 570cfm doesn't seem to be restricting it enough to notice.
Just food for thought.
__________________
Who cares how much horsepower it has, all that matters is how fast it goes!
Best run 13.23 at 106.97mph with a 2.183 60'
Times from before tune and driver mod.
67mustang302 that is some very good info on how to determin the cfm carb you need i have seen many guys with sbf's try to run 750's and such and wonder why it is kinda doggy , people don't realize that there is a such thing as overkill when it comes to carburation to much it will respond like crap and useally overload at idle and to little will starve it and raise fuel consumption.can you pm that formula to me please this will come in handy when i finally get to build a stroker
It's in that article, which is a good read. And yeah, overcarburetion is the culprit of carburetor's bad raps. Everyone thinks carburetors suck at what they're supposed to do, but don't realize that it's gotten that rep because people just use WAY too much carburetor. Vic Jr intakes and 750cfm DP's on basically stock 302's. [:@]
__________________
Who cares how much horsepower it has, all that matters is how fast it goes!
Best run 13.23 at 106.97mph with a 2.183 60'
Times from before tune and driver mod.
****All About Carbs****
