reason im asking is because ive read the hEI kinda falls off around 4-4.5k - thats what ive "read" -not experienced.. the 6a units are found cheap so was wondering - im trying to eliminate possible issues one at a time.
Can someone explain what valve float feels like? When i mash it from say 10-15mph.. it takes off but soon after it kinda starts floating, like the trans jumped into neutral (im talking pedal to the floor / WOT) with a 3k stall.. the carb seems to run well - i get 23mpg highway and it has some nice power but the top end issue is odd..
when i put in the hotcam i matched a set of single street springs, i didnt want to go dual springs cos the hotcam isnt THAT crazy on the ramps etc - or am i wrong? i used the comp tool and my micrometer to cut down the guide bosses almost equal../QUOTE]
If you go with an MSD 6a with the HEI, eliminate the module and convert to external coil, and use the HEI mag pick up only.
Valve float or spring surge generally happens higher in the RPM ranges, (unless the springs are totally wrong) and will not RPM anymore and can feel/sound like a fast mini jakebrake or like your hitting the limiter. On the dyno, it's sounds like you put a 45 gallon drum behind the engine, and your SCFM goes down and HP brutality falls of the cliff.
What was the recommended installed height and rate of the springs, what was your installed height? does the cam open pressure recommendations match your springs at the net lift your attaining?
If your ignition and valve sprigs are up to spec, you can look at the fuel delivery side of things, an inline pressure gauge during WOT would tell you this right away.
Biker and 1980RS make some great points based on experience, same here.