Thursday, January 12, 2012

Would an edelbrock 750 cfm carb be too much for a 305 high output engine?

its in a 1987 monte carlo ss aerocoupe. we are thinking there is an oversied cam in the engine, but we are not positive. so, i was wondering, would it be to much for the 305 if it were stock, and would it be too much if it had an oversized cam. thanks.Would an edelbrock 750 cfm carb be too much for a 305 high output engine?
Sorry but both answers are WRONG, and making the classic mistake of over carb'ing the engine.



You need one heII of a 305 to need a 750 cfm carb.



Formulas for air capacity

street carb cfm = rpm x displacement / 3456 x 0.85

street/strip carb cfm = rpm x displacement / 3456 x 0.95

race carb cfm = rpm x displacement / 3456 x 1.1



The 305 aint going to make power over about 5500 rpm due to its small bore size (engine with asthma, it runs out of air)



So do that math. Even if you figure with a 95% VE (need aftermarket heads, bigger cam, better exhaut, etc etc to get 95% VE)



That puts you at only needing a 461 cfm carb.



Put a 500 cfm edelbrock on it and be happy knowing you have the right carb for your app.



Everyone wants to over carb and over cam every v8 engine.



I can't tell you how many poor running 305s and 350's that have came into my shop with 750-850 cfm carbs and 240@.050" cams



If it tells you anything.. I run a 750 cfm carb with this setup

355

10.34:1 compression

Scat crank and rods

Wisco pistons

Brodix IK 200cc alum. heads

2.02/1.60" valves

solid 249/252@.050" cam with .570"/.579" lift

billet alum full roller rockers

7/16" rocker studs

th-400, 3500 stall converter

ford 9", 3.89 gears

7000-7200 RPM shift points



Thats in a camaro that race in NHRA DOT tire class.



By your, and other peoples thinking, I guess I should pull my 750 cfm carb off and put two 1,050 cfm dominators, cause if a stock to mild 305 can use a 750 cfm carb then my wild 355 must need atleast 2,000 cfmWould an edelbrock 750 cfm carb be too much for a 305 high output engine?
It should be ok it its a stock engine. Just make sure you have an inline fuel pressure gauge so you can see working fuel pressure so you dont over fuel / flood out the engine.Would an edelbrock 750 cfm carb be too much for a 305 high output engine?
It shouldn't be too much in either case.

No comments:

Post a Comment