Originally Posted by Pupsvette76
i plan to remove the muffler i have on the car hopefully that will aid a little bit with exhaust pressure i do plan to put a better set of heads on the car a little later on.. i wanna know why it wont spin past 4800 even if i bring the rpm up slowly it wont spin higher
Not to contradict anyone but I believe something is going on besides the heads having 1.94" x 1.50" valves. A turbo- if done right- will work w/them. Not as well as it could w/bigger valves and/or better heads but it should pull hard to at least 6K rpm if not higher, regardless. By 6K rpm the boost may continue to rise but there will be a plateauing of the powerband due to the head restriction past that point.
How much boost are you seeing at 4800 rpm?
Is the engine smooth all the way up to where it stops accelerating or is it missing? Is there any popping through the carb or exhaust? What
Has TDC been verified? Not just by looking at the timing tab/damper line- but by actually setting #1 or #6 to TDC and see what the line/tab says? If it's off, the entire curve isn't what you think it is. Have you tried temporarily advancing the timing just to see if it revs higher? As long as the engine isn't under a load, there's no problem w/advancing it further than you would if you were driving the car.
Has the cam timing been verified? Compression test? Leak down? What do the plugs look like, color-wise? Fuel fresh? What octane?
What about putting a carb on it temporarily, just for testing? You might be under fueled. You've verified the TB is opening fully, right?
You didn't leave a grease rag in the intake, did you?
Somewhere along the way you do need to disconnect the exhaust to be sure there's no excessive restriction there.