Trouble identifying piston - OMC 5.7

Maarko

Recruit
Joined
Feb 14, 2021
Messages
1
Hello,

I have a GM OMC 5.7 engine from 1988. One of the pistons in the engine needs replacing, but we have trouble identifying what type of piston it is that we are looking for. The standard dimension of the pistons are 101,5mm. On the pistons that are in the engine now however the dimensions are 102,5mm and 81,5mm. On the piston it says 030, and 8447P as well.

The pistons have as it seems been replaced one time before, but I haven't had any luck when contacting the previous owners.

I live in Sweden and when contacting resellers here they do not sell pistons like that, or even know what type of piston it is. Therefore, I am wondering if anyone might know what type of piston it is that I am looking for, what brand and model, and potentially where I could order it?

Thank you in advance.

Kind regards
Marko
 

Scott06

Admiral
Joined
Apr 20, 2014
Messages
6,777
The .030 means the block was bored .030 inch overbore. Thats the common US engine rebuild over bore.

look for the pistons at a US supplier like Summit Racing . What happened to the one piston? it is unusual to replace just one.
 
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