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Re-fitting pistons
Posted: Mon Oct 13, 2014 10:36 am
by Stubmiester
Has anyone got any tips on the simplest and easiest way to refit pistons back into each bore. I thought I saw an article in an a previous MMOC magazine, but cannot find it at all. Can anyone help please?
Thanks
Stuart
Re: Re-fitting pistons
Posted: Mon Oct 13, 2014 10:53 am
by philthehill
Buy if not already owned a piston ring clamp of suitable size for the Minor piston.
Before applying the clamp ensure that the piston ring gaps are at least 90 degrees away from each other and the piston is facing the right way (may be marked F (Front). Also that the con rods are the right way round and on the right journal (rods may be marked 1. 2. 3. 4 as may be the rod caps).
Apply plenty of oil to the bore and rings, apply and tighten the piston ring clamp reasonably tightly but not too tight as the piston rings have to slide inside the clamp; fit the con rod down the bore. With the clamp resting on the top of the bore give a light tap with the wooden end of a hammer handle to the top of the piston to square the piston ring clamp on the piston. Then continue to gently tap the piston/rings down the bore making sure that the bottom of the con rod engages with the crankshaft journal.
When the rings are fully home in the bore the clamp will just move free.
If the piston will not slide down the bore STOP and investigate WHY. Do not continue trying to knock the piston down as you could break one or more rings.
Do not be to timed in knocking the piston down the bore as trying to be too careful can also result in breaking piston rings.
Good luck
Phil
Re: Re-fitting pistons
Posted: Mon Oct 13, 2014 12:16 pm
by bmcecosse
I generally just feed each ring in with my fingers - that way I know they are going in ok - but it is quite 'sore' on the fingers! I have a clamp - but am wary of using it simply because I just can't see what's going on...
Re: Re-fitting pistons
Posted: Mon Oct 13, 2014 1:24 pm
by alexmcguffie
Exactly as philthehill says. If your block hasn't been skimmed or bored there should be a small bevel at the top of each cylinder which acts as a lead-in for the piston rings.
Re: Re-fitting pistons
Posted: Tue Oct 14, 2014 7:54 am
by Stubmiester
Phil, et al-many thanks-very useful. I am now down to the local garage to see if I can borrow a clamp!
Re: Re-fitting pistons
Posted: Tue Oct 14, 2014 8:55 am
by Stubmiester
Piston ring compressor purchased for the princely sum of £9.35p!!
Re: Re-fitting pistons
Posted: Tue Oct 14, 2014 9:00 am
by philthehill
Well done and good luck with the fitting.
Phil