I bought a 1976 4-bolt Chev 355 from a friend of a friend that was rebuilt by a reputable machine shop (saw the receipts).This friend of a friend had it in his old Blazer for about a month, until he parted it out to build a Pro Street car.(got bored).
Anyway, I was changing the slightly banged up oil pan and found these scratches that run parallel with the piston (piston skirts contacted walls?)on all the cylinder walls and pistons...
What would cause these and should this be fixed (is this ok)?
Hope I didnt get hosed?
Thanks
You can see the lines in question best in photos 1,2 and 5. Id take either the engine or at least these photos to the machine shop and see what they have to say.
what air filter was used on your friends blazer? see these vertical scrathes a lot on dirt cars with K&N filters dirt gets by and will put in these small scratches. If the engine was running with no issues button it up and use a good sealed paper air cleaner and forget it.Now if this was an all out race car it would be a different story but on the street your probably just fine.
Might want to take note... The scratches are down at the bottom of the cylinder which means in most cases the assembly was not the cleanest (may have come from dirt in the bottom end)... Just because a machine shop builds a short block or long block alot of them do not install the sheet metal... Who knows who put the tin in place and how careful or clean they were...?
Just because it was "rebuilt" does not mean it was done right...
But if its not using oil and the oil pressure is good it might be ok...? I would also pull a rod cap or two and a couple of main bearing caps to check the bearings for any problems...
check from the top if you can. As long as the scratches don't continue to where the piston rings travel there's really no reason to even think about them-
Thanks for the replies, I will have to look into this a little further, you can see the scratches all the way up when the piston is at TDC, I guess its a lot easier to get this fixed before it gets put in.
I bought the shortblock thats in my hotord rebuilt,off a succesful local drag race friend/shop owner who builds his own motors.It was a budget build for his tow vehicle and he didn't want to rebore the motor.Just a hone job and some rebuilders pistons and new rings.When he honed it it didn't completely take all the old scratches outta a small section of one cylinder.But it runs fine and I don't expect a problem.May not last as long as a brand spankin new clean bore but I think with good care I could pull 100k outta it...well if I didn't have 4.56s and a linelock fetish.LOL
Anyways was the motor bored??If not Maybe they are just marks the hone didn't take out??
Did you examine your oil for particals??If you have a filter off this motor cut it open and have a look for metal.If theres any small puddles of oil left in the motor anywere look for metal in that oil also.
And pulling a few rod/main caps ain't a bad idea while the pan is off.
Those scratches are nothing to be worried about. It appears to be a less than spotlessly clean assembly procedure, which happens in a lot of shops on standard rebuilds. Sad to say but true. Bolt it in and enjoy.
I concur with the others about the scratches. It also could be a bur on the bottom of the bore. I always use sandpaper to polish the bottom edges of the bores.
More than likely it's a little grit in there, it doesn't look too abnormal, that is I've seen that alot. It's not piston scuffing from overheating, which would be much worse.
You could disassembled, clean and debur and reassemble to set yourself at ease.
Brian
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