Pistons Re-building

Post Sat Sep 30, 2006 11:17 pm

Hi, a mate of mine is building his bottom half of the engine, before pushing the pistons in would he need to use the rotational sander with drill to rough the surface? as he was told no need by loads of people because the 325 pistons were taken out and the bores were smooth as hes doing a piston change, also hes planning to use semi synthetic oil as to run the engine in... is that bad?? what could happen if used this oil whilst running in?

Cheers

J.

Post Sat Sep 30, 2006 11:32 pm

If he's using new piston rings then he should really hone the bores to give a 45 degree cross hatch pattern. If you don't do this, the rings probably won't seal correctly and it will smoke and loose power.

Ian.

Post Sun Oct 01, 2006 12:38 am

before pushing the pistons in would he need to use the rotational sander with drill to rough the surface?

WTF??? I sincerely hope you mean a honing tool rather than an orbital sander

he was told no need by loads of people because the 325 pistons were taken out and the bores were smooth as hes doing a piston change

If the bores are smooth (i.e. have no honing marks / crosshatching) then he's definately looking at a rebore, because sure as shit falls downwards, the bores are going to be oval and tapered.

hes planning to use semi synthetic oil as to run the engine in... is that bad??

No probs with this at all providing it's the correct grade. The "Oilman" is the best person to ask though.

Post Sun Oct 01, 2006 10:05 am

Sooty wrote:
hes planning to use semi synthetic oil as to run the engine in... is that bad??
No probs with this at all providing it's the correct grade. The "Oilman" is the best person to ask though.

You will need mineral oil to run it in, so that the piston rings bed in. Otherwise the engine will never be run in.