carb spacer

i have a 71 charger with a 360, its suppose to run to 6200 rpm but im losing power at about 4800. so im switching from a 650 to a 750 holley, old performer intake to the edelbrock performer rpm air gap and putting a carb spacer on to clear my hood because i have a gnarly dent where my engine hit the hood and im just gonna cut it out and have a scoop. i have a open and 4 hole carb spacer, which one should i run? it is a dual plane so i want to go with the open...but i dont want to lose my bottom end. ill be running 4.10 gears and a 3000 stall. car weighs 3500 pounds.

When you say it is supposed to run to 6200, does that mean that you've been running it to 6200 with the 650 carb? If so, it's not the carb. Maybe the valve springs are goin' away??? Use the RPM manifold, you're already past the low range of the Performer anyway with a 3,000 stall converter. Try both spacers, see which one works better.

no i mean it was build to have power to 6200...but i cant really get it past 5000. ive been told its under carbed to reach 6200 rpm. its a fairly new engine, built by the local performance shop to make somewhere around 400 hp. ive also been getting detonation above 5000 rpm, or i did, i didnt try taking it above 5000 when i noticed it was struggling around 4800.

6,200 rpm's divided by 2 times 360 divided by 1,728 times 85% efficiency equals 548 cfm. The motor should rev to 6,200 easily on a 650 carb.

Its not the carb size, anyway. Sounds like it may be leaning out at high rpm.

check your distributor....might need to be recurved.....could be running out of a decent spark to support that rpm........