3800 Rod knock or Valve float???

[Aarons_GTP]

I have a 98 GTP. About 2800 miles ago I put a ZZP VS cam and new rod and main bearings, I am running stock springs, lifters, and pushrods. There is no noise at idle, actually runs great. When I get on it real quick and let off at about 4000 RPMs and anything above there is a very distinct knock, knock, knock noise. If I floor it and rev it all the way out you can't hear it over the supercharger, maybe it goes away then, I don't know. But my question is this, wouldn't a rod knock all of the time???? If anyone has comments or advise please let me know.

Aaron

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[iliveonnitro]

Yes, rod knock would be all the time. Depending how severe, it may be very faint at low RPM. Can you autotap it and see the kind of knock and other things you're getting?

And you're brave for running stock springs with any cam...you wont get those crazy 350hp+ dyno's without aftermarket ones and higher shift points though.

I say invest in some stiffer springs, keepers, and O-R/lightweight pushrods.

 

[BumpinGTP]

im thinking valve float, change your springs

 

[rob]

Originally posted by BumpinGTP@May 17 2004, 08:31 PM
im thinking valve float, change your springs

Yea, try that...Your performance suffering? If it is you may be suffering from some false KR due to the vibration. You can install a set of 105 0r 130's.

Could be a worn valve guide aswell. Try to isolate the knock but you should use stiffer springs with a larger cam anyway.

 

[alexgtp]

HOw many miles on the car when you did the cam?
I also think you might have some valve float.
Definately change out springs and retainers when doing a cam.

 

[dole21]

he did the motor swap and put in the motor with umm 38,000 miles roughly i believe it was. it runs good....minus the noise

 

[Aarons_GTP]

I was going with valve float too. I would think that in theory valve float would happen at high rpms.