well while the engine is idiling i can hear a faint sound and sounds alot like it's knocking. the knocking sounds like it's coming from the bottom end of the engine and is more prominent while the engine is cold. my theories are loose convertor bolts or a worn front pump bushing(on trans). i haven't had a chance to check out my theories yet, but will do so tomorrow. i hope that's it's not the engine. the vehicle/engine only has 88K original miles. any ideas? thanks for any replys.

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86',88',89' IROC-Z, 350 TPI, 700-R4

94' Formula, LT1, 6spd

 

Hey, I'm really curious about what you find out. I've got one 86 IROC that runs great, but I just bought another 86 IROC that has a knocking/thumping noise. The guy I bought it from said he was told in was a main bearing (freshly rebuilt 350 still in it's break in period). It has great oil pressure when idling cold. I was also going to check the torque converter bolts and the harmonic balancer when I get the time. Let us know what you find. Thanks.

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Z's r Best

 

a trans problem with the converter bolts will make un unsteady clunking noise at idle. if its a constant sound like you said from the bottom of the engine and louded at startup thats forsure a bearing going south.

 

Well it only does it at idle and does not get any louder at engine speed increases so i'm just hoping for loose bolts or anything other than the engine. i hope it's nothing major. the 88' is my favorite.