skodajag Posted February 19, 2006 Report Share Posted February 19, 2006 Greetings All I have a set of 87mm Powermax pistons and liners which I want to install in my TR3A. A friend has very kindly given them the once over, and the only problem seems to be with the liners: all have a pronounced ovality, they are not too badly tapered from top to bottom but are definitely oval, sometimes by up to 8 thou. We're not sure whether this is acceptable or not and would appreciate any advice from anyone out there who can help. Thankyou Jonathan Dollimore Quote Link to post Share on other sites
jonlar Posted February 19, 2006 Report Share Posted February 19, 2006 Hi Jonathan, as no-one else has come back to you yet, I'll put my 2 pennyworth in, they may true up once in the block, or a light honing may true them up enough, again once in the block - are they new or have they been used? If used, I believe they may wear more on one side than the other (in one spot even), someone else will confirm or refute this. Quote Link to post Share on other sites
Nigel Lay Posted February 19, 2006 Report Share Posted February 19, 2006 Hello Jonathon, I managed to get hold of a set of +10thou rings to go on the pistons that went into TS952. I had two sets of liners and picked four of the best. Our local engineering shop then honed them out to get rid of most of the ovality in them and to accept the +10 rings. I wonder if there is another set of +10's out there. As Jon said, a light honing on your liners as they are may well be enough. The ring gap is listed as .003" to .010" so there is a wide tolerence. If you have a tight ring gap as it is you could hone out to the maximum gap and get rid of virtually all the oval in the liners. Somebody with more knowledge may well come up with other idea's. Nigel Quote Link to post Share on other sites
unclepete Posted February 19, 2006 Report Share Posted February 19, 2006 Jon For the cost of having them engineered why not go for a new set of liners? They are not that expensive and will save you heartache and worry! As I presume the set you have are used, the ovality would be due to the fore and aft motion of the pistons within the bores (side to side if you look down on the engine), I believe the old cure for a bit of 'piston slap' was to turn each sleeve 90 degs? Unc Quote Link to post Share on other sites
skodajag Posted March 2, 2006 Author Report Share Posted March 2, 2006 Thanks everyone - I think I'll probably get a new set of liners. Quote Link to post Share on other sites
david ferry Posted March 2, 2006 Report Share Posted March 2, 2006 Jonathan I have an unused set of 87mm pistons, liners and rings for sale. Originally supplied by Revington TR so no quality issues. Contact me if you are interested. 01295 680598 Regards David Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.