Thread: chevy small block 355

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Originally Posted by bigdana12

Rig: bored .30 over, forged pistons, floating wrist pins, cast steel crank, lunati cam, .540 valve lift, 2500 rpm stall, th350 tranny, 670 street avenger carb, dart 2.02 200cc runner heads.

Car: 1979 Z28 camaro.

I am hearing a slight bassy knock from the passenger side of the car. Before the rebuild, i made sure my measurements were good. and they were. I start it up for the break in. sounded beautiful, but it had an extremely low low tick, could barley hear it. so i changed the oil with 10w30 valvo. After around 120 miles put on, the tick sounds like a slight bassy knock from the passenger side, not the lower, the upper. I noticed and my machinest noticed. that the block wasn't casted correctly. Number 4 piston hole was actually some how curved in the piston hole itself. it basically had a small swirl in the hole. well my machinest took most the swirl out, but didnt bore it too far over for piston slap. idk. im lost. it does it on first start up, then when it gets warm its gone.


the slight knock isn't major, its not like a hammer hitting my floor pan. but it's very steady knock.

but even before i rebuild it, the engine always made weird noises. I guess its the ghost in motors.

i bored engines all the time there no way in hell if the bore is worn there going to be a hole out of shape less the bore never cleaned up the it should of gone to 040 . on honing ..a bad bore honed strait most all of the time will be past the size limit the piston can take. depending on the alloy of the piston it may just be loud till rebuild time or just loud for a short time till piston skirt breaks off many pistons now have a hi silicon make up run them to loose and it not good.