Fireman049 Posted September 13, 2012 Report Share Posted September 13, 2012 I've removed the engine from my 3A and intend fitting a spare engine block. I'll be using my original pistons and liners. There is little sign of a 'step' in the liners. Would it be advantageous to rotate the liners by 90 degrees when refitting them? Tom. Quote Link to post Share on other sites
RogerH Posted September 13, 2012 Report Share Posted September 13, 2012 I would also be interested in the answer. Roger Quote Link to post Share on other sites
Guest ntc Posted September 13, 2012 Report Share Posted September 13, 2012 No The liners should be stamped with pistons. New liners NA however you must remember the none thrust side Quote Link to post Share on other sites
stuart Posted September 13, 2012 Report Share Posted September 13, 2012 (edited) That certainly used to be the way to extend the life of them. You would be best to check for a step on the top and the amount of ovality to see if its worth it. FWIW when I rebuilt the engine on my 4a I gave the old pistons and liners (done 150K) to one of our local members and they are still going strong in his 4 many years and umpteen miles later. Stuart. Edited September 13, 2012 by stuart Quote Link to post Share on other sites
Guest ntc Posted September 13, 2012 Report Share Posted September 13, 2012 They will be oval.look at the pistons also Quote Link to post Share on other sites
Motorsport Mickey Posted September 13, 2012 Report Share Posted September 13, 2012 Tom, Depends on whether you wish to achieve the absolute maximum power. The pistons are made oval to start with anyway and are only there to carry the piston rings which are the actual closing agent , as Stuart says in the impecunuous 1950s you'd put 150k on the liners rotate 90 deg renewing the thrust face of the liner (the side with the most step on) and then another 150k etc until all 4 sides are used. I seem to remember it being stated in one of the old TR publications (rather humourously I thought) "you can achieve reasonably long engine life by this method" ! As stated in TR Technicalities the shape of the liners in the block moves about like a jelly when the head is torqued down and despite all this...the engine works. It's not a watch ! I'd be quite happy to hone the liners refit and reuse. Mick Richards Quote Link to post Share on other sites
Guest ntc Posted September 13, 2012 Report Share Posted September 13, 2012 Mick The liners should be set with a solid lump not the head for race use,that way they do not wobble like jelly Quote Link to post Share on other sites
Motorsport Mickey Posted September 13, 2012 Report Share Posted September 13, 2012 Neil, Admitted, but when the head is refitted if the cylinder bore has a "Talyrond" taken of it all our good work is as naught cos even then the bl**dy tube losengzes all over the place. (confirms this in Technicalities). Sometimes you just have to work with the items as designed half a century ago, encouragingly despite all our fears the engines still work (and well). Rehone the liners, refit them 90 deg to thrust, drive it like you stole it. Mick Richards Quote Link to post Share on other sites
RogerH Posted September 14, 2012 Report Share Posted September 14, 2012 (edited) Hi Mick, I assume you fit new rings!! - Anything special. Roger Edited September 14, 2012 by RogerH Quote Link to post Share on other sites
Ashley James Posted September 14, 2012 Report Share Posted September 14, 2012 I wouldn't fit new rings if there's a step in the liner because they'll probably break. However The TR Shop are selling off 87mm Piston liner sets for £250, so I'd buy them. I've just stripped an engine with a slight step and bought new piston/liner sets. Quote Link to post Share on other sites
RogerH Posted September 14, 2012 Report Share Posted September 14, 2012 Hi Ash, although never having used them I believe there are rings with a step in them to allow for the ridge - is htis true or am I dreaming again. Roger Quote Link to post Share on other sites
Guest Mick RichardsChange... Posted September 14, 2012 Report Share Posted September 14, 2012 Hi Roger, Nothing special in the way of rings, review the Technicalities and choose from amongst them and what is available from the specialists to suit yourself. As you say because the used liner would have a ridge in it when turned (even after honing)choosing a RD (ridge dodger) ring set is essential. However about 33 ye...hrumph some time ago I do remember building an engine on it's 3rd liner turn (2 previous builds by other people) and noticing that the last builder obviously couldn't get a ridge dodger set when the engine was last rebuilt. They had improvised by grinding a 30 deg? angle on the top face of the of the top ring which allowed the ridge to miss the ring at TDC. Obviously a steady hand and a good eye neccessary not to compromise the ring but that engine still had good compression and oil usage and was being rebuilt because the last owner after 8 years of ownership with him had done about 90,000 miles on it (that was a lot back in the eighties)and thought the engine should have a little TLC ! These engines are robust and if you give petrol and a spark in about the right amounts and somewhere in the right time frame just want to keep on working. If you follow the workshop manuals and the good "coarse TR practical knowledge in Technicalities" and available from this forum, you will get good performance (bearing in mind the engines age and limitations), good mpg (4 cylinder anyway) excellent fun and the ability to rebuild the brute even at the side of the road if neccessary. Mick Richards Quote Link to post Share on other sites
ianc Posted September 14, 2012 Report Share Posted September 14, 2012 Roger - 50 years ago, one could obtain stepped rings to avoid the problem of new rings being shattered when the top one hit the step. I had to replace a pair of pistons on my TR2 (the originals cracked right across the crown - I know not why - but I could still achieve 90 mph, leaving a huge trail of smoke behind me!), and I made sure that the top ring was stepped. We are in a different era now (TRs no longer bought for under £200, repaired with whatever could be found at a breaker's yard, and driven till they fell to pieces), so I imagine that most folk tend to fit all new parts. Ian Cornish Quote Link to post Share on other sites
Guest Mick RichardsChange... Posted September 14, 2012 Report Share Posted September 14, 2012 Hi Roger, Passing each others postings, you are correct. Ridge dodger ring sets were available with a step in the top ring, small but noticeable perhaps 10 thou, to miss the ridge worn on the thrust face of the liner when reusing a used liner. See my posting above, the ridge in the liner is only some 4 thou perhaps in the worst case, so as related above there are other ways of skinning a cat if not available ! Mick Richards Quote Link to post Share on other sites
TR24178 Posted December 13, 2012 Report Share Posted December 13, 2012 I remember we used to chamfer the top ring if a dodger ring was not available, smooth disc in a grinderette, clamp it in the vice and gently spin the piston ring to give the clearance and avoid that noise!! Those were the days!! But it worked and the engine had a new lease of life! Quote Link to post Share on other sites
Colin Fairhurst Posted December 13, 2012 Report Share Posted December 13, 2012 Hi Tom, I recently received a set of 87mm liners and pistons and rings from the TR Shop and one set of the three sets of rings have a step in one of the outer edges. The instructions showed these to be used for the 2nd ring down with the new liners. I think it would show them as the top rings with worn liners acting as 'step dodgers'. In the event one of the rings was broken in transit and the replacement ring that they sent had a chamfer on one of the inner edges. I don't know what the chamfer is for. In the end they sorted out a set all the same. Regards, Colin Quote Link to post Share on other sites
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