A friend and I have been working on his 78 Z28 this weekend. He got the thing for 700 bucks and it will be a project for the next few years. Anyway, the motor has a horrible knocking noise that I have determined is not piston slap, timing, or a collasped lifter since these things tend to have distinct noises. I put a stethoscope on all the cylinder walls on the block and determined the sound was only coming from the # 5 cylinder. It is a distinct hollow, metallic knock that is rather loud and does get louder as rpm increases. I am afraid to find out what it is. Is this rod knock?? If so I suppose the entire engine will have to be torn down and rebuilt, right? Just looking for opinions here. Thanks.
bsa

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"If they do not run, Then they will die." - Stonewall Jackson
#3
'87 IROC, 355 TPI, Converted to SD, 700R4, B&M Megashifter, 3.42, Trick Flow Twisted Wedge Heads, Edelbrock Intake, Accel Runners, Comp Cam, Crane Gold rockers, Lucas 24# injectors, Edelbrock headers, Flowmaster 3'' exhaust, Mallory Ignition, Transgo Performance Shift Kit, Corvette Servo, 2,000 Stall Torque Converter

 

Hmmm, sounds like it could be bad bearings on the #5 piston. Is the sound very low in the block, or higher up? Could also be a knock from the wristpin. Any idea if the car was ever overheated? How's the cooling system look?

HTH,


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<bold>Steve Ragusa - '85 TPI Monte SS</bold>

Way too many mods to list...check out www.bowtiepower.com for the info!

 

OK, go check that out and I'll post back here in a few........
bsa

 

Its coming from what seems to be the upper middle of the cylinder. I think the thing is shot. Time for it to go.
bsa