virtigo8776

just seeing what cfm people usually recommend for a 383 engine. right now its running an edlebrock 1406 600cfm.. seems to be a little underpowered for it so im just looking for opinions

five7kid

iTrader: (14)

Would need to know more information.

From a peak power standpoint, a 600 would feed a 100% VE 383 to 5400 RPMs. However, conventional wisdom (and real-life experience) say a larger carb will make more power overall.

Generally speaking, a 750 will handle your basic mild 383. However, I know guys who run Dominators on their 383s at the track. So, we'd have to know more about your engine to give a meaningful answer.

virtigo8776

383
.30 over bore 400 crank
heads 76cc chambers, 194 exhaust valves
mild cam(cant remember size ofhand but i got one with smooth idle and was showingbetter low end torque)
headers and new exhaust 2.5"
edlebrock performer intake(forget which model but its the lowest of there performance ones since i was having problems clearing the hood)
700r4 trans newly rebuilt

let me know if you need any other information

note:the lower end is the weakest area in its power curve

virtigo8776

the kits said 9.8.1 compression with 64cc heads so im not sure how much the 76cc alters that. pistons are flat top.

the guy i had do the machining on the 350 block said i probably need a bigger carb and true dual exhaust. wasnt sure about the exhaust, this is my first project car so im still learning but im assuming that if the exhaust was restrictive it would hurt the high end more than the low end power. which so far its more the low end thats lagging most.

ps the trans does have the torque converter kit on it, not the one that has the button to lock it up manually though

virtigo8776

ps when it was dyno tuned it showed 200rwhp and 360 torque. was only worked on for 40min, not sure if thats long enough to get it tuned all the way up on a dyno

Ukraine Train

The rule of thumb formula is (displacement in inches X peak RPM / 3456) X volumetric efficiency. Assuming a VE of 85% and peak RPM of 6k you get:

(383*6000/3456)*.85 = 565cfm

so it sounds like a 600 is big enough but I dunno, it just seems like it would be too small for a 383.

five7kid

iTrader: (14)

What heads are those? Sounds like 882's, which, if that's the case, 600 cfm is more than enough. A 750 may help a little.

virtigo8776

not sure what kind of heads.. the guy i had do the machining refurbishes used heads and recommended those. he took them off a 350 engine but i dont know much other than that and the valve and chamber size

five7kid

iTrader: (14)

You might want to pull a valve cover (or two) and check. If that's what they are, his recommendation wasn't based on your best interest.

virtigo8776

what kind of heads should it have. dont use it for racing, mainly interested in low end performance

five7kid

iTrader: (14)

When you said "underpowered", I assumed you meant WOT performance dropped off with rising RPMs.

If it's low RPM torque you want, then small port heads are the ticket. Heads, cam, intake and carb need to work together to produce the results you're looking for. It sounds as though the intake and carb are okay for your intents. Some more details on the cam would be helpful. Generally speaking, though, 882 heads don't help in any part of the powerband. L98 heads, World S/R Torquers, etc., would be much better.