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68 camaro 402 yes I ran the numbers. 30 over some crazy 500 inch lift cam. Last year popping at 4,000 rpm. new every thing dist,cap,rotor,plugs hah, wires for headers. All I could find was some ngk. yea popping at 4,000. Got new ac delco Iwill get the number. O yea she's back the car pulled up and the shift lite came on. I thougt the motor was toast. Start with the basics. 50 plugs. the fix The dist,wires, where not the issue.
 

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68 camaro 402 yes I ran the numbers. 30 over some crazy 500 inch lift cam. Last year popping at 4,000 rpm. new every thing dist,cap,rotor,plugs hah, wires for headers. All I could find was some ngk. yea popping at 4,000. Got new ac delco Iwill get the number. O yea she's back the car pulled up and the shift lite came on. I thougt the motor was toast. Start with the basics. 50 plugs. the fix The dist,wires, where not the issue.
Sounds like the valve springs have laid down. Pretty common sign when the engine hits an RPM time after time and just pops and shudders refusing to go any higher.

Bogie
 

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Sounds like the valve springs have laid down. Pretty common sign when the engine hits an RPM time after time and just pops and shudders refusing to go any higher.

Bogie
X2. If you think there is any chance that it's the timing, then back it off 4 degrees and see if it happens at the same rpm. If yes, then I'd be aiming at valve springs as well.
 

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X2 on valve springs, could also be a valve timing issue, was the cam degreed when it was installed/engine assembled?
 

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Are you sure it is not the distributor? Has an advance kit been installed? Has the coil been replaced with an aftermarket coil? Do not run with vacuum advance hooked up. Another thing what is the casting numbers on the heads under the valve covers. They might be peanut port heads. They are good up to 4000-4500 rpm then it's like hitting a wall. If you have a vacuum gauge it will tell you if you have a problem with springs. Here is a good article to read. http://www.73-87.com/7387garage/drivetrain/hei.htm
 
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