Well, I've been chasing a pretty strange problem for a while.. when accelerating as my engine gets up near 5600 rpm I start to hear a clattering sound, that progresses to an almost grinding sound towards 6000 rpm. I cant seem to figure it out.

I have ruled out valvetrain problems I believe as I have replaced the stock springs and rockers with pro magnum SA 1.6 roller rockers and CM EX-614 springs. (iron head LT1 btw).

I have ruled out transmission as that took a dump and was rebuilt a year ago (oh, and 3 times since then under warantee, which is now out, yay.)

so... I dont believe it to be detonation as I dont see anything wierd on my datamaster scans.

in neutral with no load I was able to rev it to 6300RPM for a second with no clatter...

power is good. no drop off associated with the sound.

any ideas? just to be safe I have my car completing my shifts by 5500rpm..

on impalasforums.com I found a guy who had the same problem with a completely different engine setup, never figured out the problem. never had a problem with many runs on the car. sold it a year later to by a z28... so no help there.

Thanks for any ideas!

 

ahh, I know I didnt stump you guys with this one

any input? should I post this in advanced tech?

Thanks again -Ryan

 

What car do you have, how many miles are on it, and which mods do you have?

A sig would really help people answer your question

Thomas.

 

Remove the serpentine belt and see if it still does it. Mine did something similar when my crank pulley was splitting in half.

 

Do you have poly replacement mounts on the tranny and motor? Mine does it like crazy from the tranny.

 

Alright, I got a sig up.

Thanks for the suggestions.

I'll try removing the belt & see what happens.
& no, I have not replaced the factory mounts with poly mounts.