Hello All,
If anyone has a stock 502 flat top piston can you measure from the top of the piston to the top of the wrist pin. I put some probe flat top pistons in and they are .024 in the hole . I believe it should be between .005 to .010 Thanks for any help .

alec,
I just measured some stock JE's in a SC 502 this afternoon. The compression hgt was 1.645" subtract 1/2 of the pin diameter and you would get 1.150" for the dimension you are looking for. These were dished pistons but I am pretty sure the compression hgt is the same on all of the JE 502 slugs.

If the block has never been decked, I would not be a bit surprised at them being down that far. Which Probe # are you using ? I just glanced at thier online catalog and it looks like thier 502 pistons are the same hgt as the JE's I have 1.645" (top of piston to the center of the pin)

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

.024 sounds about right
is it a factory assembled piece ?
or someone installed it to that height ?
you could have the block decked to get it up in the hole more if your looking for more compression,
most factory installed stuff sits about .020-.030 in the hole

hell my shortblock I just took apart the pistons were .050 in the hole (flat top BBC piston)

.005-.010 that would almost be a 11:1 compression ??

I don't think u want that.

Alecsammy:

Please don't take offense, but My suggestion is you don't have enough knowledge about these engines to be doing what you are doing and what you are ordering. You are not going to learn everything you need to learn about building good marine engines on the internet, so Save your self the trouble and grief you will expierence now and in the future. Let a qualified marine engine builder build you an engine of your spec and choice. Old Raylar proverb say "a Dentist and a Brain surgeon are both doctors, but you would not want a dentist doing your brain surgery!!"

Best Regards,
Ray @ Raylar