Thread: chevy small block 355

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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.

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.

Change the oil and put straight 50 wt. back in it, see what happens. If it's piston slap, that should quiet it down. I didn't say it will cure it. Nothing short of a piston that fits the bore will cure it, but at least you can find out what it is.
I had a cracked piston on #1 SBF a few years ago. Pretty loud.

well the casting of the block wasn't the best. It's a first gen chevy motor. I placed the piston in number 4 and it didn't slop around from pushing to side to side. I have no clue whats the noise is coming from. someone told me to put 10w30 mobile full synthetic oil in it. i did that. and it knocks on cold start ups, but goes away when it's warm. When the people drilled the cylinder walls for the block, they weren't perfectly lined up. everything is new on this motor, besides the block.

i'm probably going to take off the passenger side valve cover and check my rocker arms. make sure ones not tightened down all the way. it doesn't effect the performance though. it'll burn tires and takes off bad out of hell.

holes are bored not drilled . they are set off the deck or oil pan rail or main saddle /cam centers spacing or centering could be off some but nothing your going to see . if bored the boring bar gets centers on the old worn part this is were the top ring stops or the lower part of the old bore . has alot to do with what i going to do and how much wear is in the bore

even side ? check fuel pump if you have one

Borrow a stethescope, or put a long screwdriver handle against your ear, you can narrow down where the sound is the loudest. Its really hard to tell anything without hearing it up close and personal..
In the late 70's I slapped rebuild kits into chevys and got away with a LOT of things I consider heresy today.. A bore being slightly off center is common but usually doesnt affect a street motor. I could rant a bit on your machinist... but,, again, without being up close and personal I dont know the circumstances/situation...

the block only had 56k on the motor, a lip wasn't even showing on the cylinder walls. i think i have a rocker arm tightenedd down too much or my fuel pump rod is damaged. I'll look through it and keep posted.


my machinest is a really good friend of the family. i never had second thoughts about him doing stuff for the family or business. He delivers and he delivers rightfully.

If your machinist is a friend of the family-----------------------

You can take off or short out the wire to the plug on that questionable cylinder and if its a piston slap it will probably quiet down--------

Full floating pins?????? how much clearance on them????/seems to me like you have a mixture of things that aren't the best choices for compatibilty----forged pistons but cast crank??

How did the machinist do the bores?????boring bar with a block fixture??? or just clamped to the block deck????how was the bores honed???electric drill and bottle brush or a CK10 type hone with deck plates torqued down?????I'm not trying to be an ass hole , but there are lots of shops that don't have proper equipment to do a top level job and they take short cuts and talk a good line of bs

no, he's a really good mechanist. no questions asked. He makes parts for the farm. anything to do with the diesel motors or implements. he's been in the business for over 40+ years. i couldn't tell you the specs. he told me but i forgot what they were. but he's precise as hell. he did over 100's of motors. sleeve to regular non sleeve motors. he knows his shit really well.


i bought the rotating assembly from summit.

Connecting Rod Material:Forged 5140 steel
Piston Material: Hypereutectic aluminum
Wrist Pin Style:Press-fit ---- now full floats
Crankshaft Material:Cast steel

sorry. the rods are forged.

Originally Posted by bigdana12

no, he's a really good mechanist. no questions asked. He makes parts for the farm. anything to do with the diesel motors or implements. he's been in the business for over 40+ years. i couldn't tell you the specs. he told me but i forgot what they were. but he's precise as hell. he did over 100's of motors. sleeve to regular non sleeve motors. he knows his shit really well.


i bought the rotating assembly from summit.

Connecting Rod Material:Forged 5140 steel
Piston Material: Hypereutectic aluminum
Wrist Pin Style:Press-fit ---- now full floats
Crankshaft Material:Cast steel

sorry. the rods are forged.

BINOG HYPEREUTIC pistons are not forged and they will not take any added piston to wall go back to post #2 they do not grow like a 2618 . i done many bore jobs and i redone some were i had to bore the next size up from the shop down the road from me. they would tell you they have over 100 years of added machine time under there shop roof . well i stick with my 20+ years doing 100s of bores and getting paid to fix there screw ups

Originally Posted by bigdana12

no, he's a really good mechanist. no questions asked. He makes parts for the farm. anything to do with the diesel motors or implements. he's been in the business for over 40+ years. i couldn't tell you the specs. he told me but i forgot what they were. but he's precise as hell. he did over 100's of motors. sleeve to regular non sleeve motors. he knows his shit really well.


i bought the rotating assembly from summit.

Connecting Rod Material:Forged 5140 steel
Piston Material: Hypereutectic aluminum
Wrist Pin Style:Press-fit ---- now full floats
Crankshaft Material:Cast steel

sorry. the rods are forged.

Have you had the machinist who did the work listen to the engine? If there's a noise in the engine then something isn't right! People reading to the description of a noise (we all describe things differently) can do little more then render an educated guess, someone knowledgeable about what's been done inside the engine right there listening to it could probably pin point the problem quickly.

Originally Posted by pat mccarthy

BINOG HYPEREUTIC pistons are not forged and they will not take any added piston to wall go back to post #2 they do not grow like a 2618 . i done many bore jobs and i redone some were i had to bore the next size up from the shop down the road from me. they would tell you they have over 100 years of added machine time under there shop roof . well i stick with my 20+ years doing 100s of bores and getting paid to fix there screw ups

----and you've never made a mistake, right???????? be careful, the last man on this earth that was perfect got crucified!!!!

Pat's not qualified for that ----he failed the "burn" test------------



Pat and I are a lot alike in what and how we do things and with me it mainly came about because "OTHERS" made lots of common mistakes and dumb things---Pat and I have several thousands of dollars of equipment for the sole purpose of doing things right and exactly on size---and everytime we look at a mike or indicator, its not acceptable for it to be "close enough"

And I'll go a little farther to make the point that this late model CNC machines run by computer nuts won't get the results that you are looking for(unless you have the level of machines that " Nascar" type shops have and they are starting out with cores that you can't get)