harrytr5 Posted April 14, 2020 Report Share Posted April 14, 2020 (edited) On this rebuilt TR4A engine from triggers broom that has had minimal run time on just start up I believe, it has the four ringed pistons which I read somewhere years ago that they could be a problem with the ring lands below the gudgeon pin fracturing, is that a fact and if it is I will change them. The liners seem to be level with the block. do they crush down when the head is torgued or must they protrude at all times by 5thou +/-. I have good knowledge of sixpots and the four pot is a huge learning curve for me. I have the Maxz rear seal conversion. Do I need the centralising tool as fitting it on loosely and turning the crank will centralise it or am I missing the point. The big end bolts have tabs on them to lock . As it is a late TR4A engine should it not have stretch bolts? How do you tell what bolt is what ? I guess change them out anyway. The head will need to be unleaded although has been rebuilt. All good fun and keeps the brain ticking. Be Kind and look forward to the replies. Regards Harry TR5 Nutter Edited April 14, 2020 by harrytr5 more info Quote Link to post Share on other sites
stuart Posted April 14, 2020 Report Share Posted April 14, 2020 (edited) You do really need the centring tool for the Marx seal kit to work properly. I have one if your stuck. Liners do need to protrude by the specified amount and it needs to be even all round and front to back. Mickey will be able to lecture you about this or you could always search on here as there is days worth of posts on how to do it properly, not convinced that 4 ring pistons are a problem though if your going to race it then that maybe different. Stuart. Edited April 14, 2020 by stuart Quote Link to post Share on other sites
Mark1965TR4aBRG Posted April 14, 2020 Report Share Posted April 14, 2020 If you have the opportunity to, do check the actual liners are within spec height wise too. My rebuilt engine had a very slight yet persistent water loss issue that was traced to one of the liners being shorter than the other three. Quote Link to post Share on other sites
Motorsport Mickey Posted April 14, 2020 Report Share Posted April 14, 2020 (edited) C'mon Harry, you've trawled the forums over the years. There are days worth of reading on the MOST important part of the TR 4 pot engine,... liner heights, some of it is outlined here https://www.tr-register.co.uk/forums/index.php?/search/&q=Liner height&quick=1 It can be summed up in a Micawberism ..liner heights between 3 and 5 thou...oh joy unconfined ! ...liner heights uneven or below 3 thou or markedly above 5 thou (I've run 6 thou on a race engine...deliberately)...disaster. It is the single most important feature of the engine, and when correct can give you a lifetime of reliable motoring but if incorrect can scrap your engine and all your expensive internal parts you may go for. Mick Richards Edited April 14, 2020 by Motorsport Mickey Quote Link to post Share on other sites
BlueTR3A-5EKT Posted April 14, 2020 Report Share Posted April 14, 2020 4 hours ago, harrytr5 said: On this rebuilt TR4A engine from triggers broom that has had minimal run time on just start up I believe, it has the four ringed pistons which I read somewhere years ago that they could be a problem with the ring lands below the gudgeon pin fracturing, is that a fact and if it is I will change them. The liners seem to be level with the block. do they crush down when the head is torgued or must they protrude at all times by 5thou +/-. I have good knowledge of sixpots and the four pot is a huge learning curve for me. I have the Maxz rear seal conversion. Do I need the centralising tool as fitting it on loosely and turning the crank will centralise it or am I missing the point. The big end bolts have tabs on them to lock . As it is a late TR4A engine should it not have stretch bolts? How do you tell what bolt is what ? I guess change them out anyway. The head will need to be unleaded although has been rebuilt. All good fun and keeps the brain ticking. Be Kind and look forward to the replies. Regards Harry TR5 Nutter BE Bolts Two types as you say -Is there a part number stamped on the hex head? BOLT, (used with tab washers) 105312 Notes: The early connecting rod bolts (part no. 105312) must be used with tab washers (105313). BOLT, self-locking, (used without tab washers) 138528 Cheers Peter W Quote Link to post Share on other sites
harrytr5 Posted April 14, 2020 Author Report Share Posted April 14, 2020 Thanks all for your contributions. When I have finished the body work, I will then look at the engine again. Because we are not allowed out except for a daily walk etc I am forced to work in the garage (so you could say I am happy as a pig in sh*t) so things are progressing along. Regards Harry TR5 Nutter Quote Link to post Share on other sites
Andy Moltu Posted April 16, 2020 Report Share Posted April 16, 2020 The other thing with the liner heights is there should be no lows between highs even if they are within tolerance. Quote Link to post Share on other sites
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