Piston damage question

[ric812]

I just traded a motorcycle for a SBC engine. The #1 piston on shows signs of hitting a valve.
My question is do I need to replace it or can I smooth it out some? I have never had an engine with this type of damage. The Pistons are 2244P TRW. I believe they are forged. I am planning on rebuilding the engine. Any help would be great.

[AussieinNC]

Others will chime in I am sure...but here is my 2 cents worth....

What is the engine supposed to be? 350? 327? 307?

Throw that piston away, its junk....

The head that was on that side will need to be carefully checked for vale damage and valve stem wear....

You should also check the cam and lifter associated with the failed cylinder

[ric812]

It is a 350 bored 40 over. I don't have the heads or the lifters. And the cam is being replaced. Thank you for the information.

[Dead Parrot]

IMO - replacing that piston is the best solution. If budget is an issue, can always try a gentle dremel type smoothing. Just accept the risk of the piston face having a flaw that might cause another engine rebuild. Inspect the rod, rod bearings and crank bearings on that cylinder as well. They also took a hit.

[AussieinNC]

That piston damage has been caused by the engine swallowing a metallic object...

When an object thicker than the deck clearance is swallowed, it will and does cause the piston to be subjected to excessive stresses.

The piston is most likely cracked through the pin journal area or the skirt area....

A 350 that is already plus 040 has one rebore left...up to .060 over, without going to special size pistons...= more dollars....

However, the cylinder walls get very thin at .060 over....

Is this engine a roller cam engine or a flat tappet cam engine?

Is the engine a 4 bolt main or 2 bolt main ?

What is you expected use for the engine?

Have you removed the piston and rod and checked the cylinder walls for damage?

If its a flat tappet, 2 bolt 350 already at +0.040....it has a future as a street engine...others may disagree, but after building well over 300 of these small blocks over 35 years, you tend to have an informed perspective.

I hope that bike you traded was a el cheapo...if its a 2 bolt 040 over 350, its worth $150 max, especially with a damaged hole...

[JMac11]

My 2 cents, but if the wrist pin is free and the ring grooves aren't collapsed, run a file across the top of the piston to remove the sharp edges and put it back together. The marks on the piston are that of a exhaust valve stuck open, broken spring or retainer. To each his own

[BigBird05]

You need to pull, examine and or replace that piston. You will need to examine the cylinder bore for any damage. I would replace that piston and not trust it. I also have built 200 plus engines and seen some blow up after a cheap rebuild. Trying to save money usually costs more money.

[DieselSJ]

Originally Posted by BigBird05

You need to pull, examine and or replace that piston. You will need to examine the cylinder bore for any damage. I would replace that piston and not trust it. I also have built 200 plus engines and seen some blow up after a cheap rebuild. Trying to save money usually costs more money.

^^This^^