Originally Posted by zipper06

I'll weigh in at the risk of being critised. You haven't stated (that i have read) what size headers you have, IMO you have to have atleast 2 1/4" to 2 3/8" headers on an engine that size and 4" to 4.5" collector. That would cause the 6500 RPM limit also the evac system on the dyno could effect the vacuum reading at 6500. Ofcouse the dyno does not show what is the real effects at the track. There's 3 or 4 things that could cause it to not run above 6500 RPM. "1" valve springs with the size valves you are running needs to have well over 250lbs. I run 300LBS on 2.140 Titatium on a 434" motor, and i'm sure your's are 2.250 or bigger. I don't know what size cam you have but anything over .750 it should run 7500 RPM's with ease. What concerns me most is that the carb flowed more intake cfm than the Injection. That to me tells me that the exhaust couldn't get out. INO if it can't get out (headers) it can't flow IE: equals high oil pan pressure. A vacuum pump should run 18 to 20 inches of vacuum, anything more that that will dry up the cylinder walls and cause schuffing of the cylinder walls. At no time should it turn to pressure in the oil pan. Again the dyno evac system is not the same as a real run down the track.

These are just my opinion based on previous experience and by no means should it be taken as the cure to your problems.



Zip.