Darren Groves Posted March 27, 2017 Report Share Posted March 27, 2017 Decided to strip down my 'old' engine, when I say old its probably not done 10k miles but has never been a 'happy' engine. In the last couple of years compression has been down and its suffered from excessive crankcase pressure, hence the reason for rebuilding my original engine. I never did like the fast road camshaft I put in it either. I took the head off and there were signs that the gasket had started to give way between cylinders 1 & 2, it did this a year ago. But when I took the pistons out, the top ring on each of them was broken, these were new County pistons and rings. Now I have read that County rings aren't great, but to have 4 break and the same ring on each piston seems odd. I guess it doesn't really matter why as the new engine is now in, but curious as to why it would happen. Link to comment Share on other sites More sharing options...
Qu1ckn1ck Posted March 28, 2017 Report Share Posted March 28, 2017 Did you re-bore before fitting the new pistons ? If not, there may have been a wear lip at the top of the bores sufficient to break the rings. Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 28, 2017 Report Share Posted March 28, 2017 In the good old days of get out and get under they used to make a stepped ring to use in ridge topped bores pete Link to comment Share on other sites More sharing options...
Darren Groves Posted March 28, 2017 Author Report Share Posted March 28, 2017 Block was rebored and new pistons & rings fitted, so no lip to do any damage. Link to comment Share on other sites More sharing options...
dave.vitesse Posted March 28, 2017 Report Share Posted March 28, 2017 Food for thought. Darren thanks for the info. Dave Link to comment Share on other sites More sharing options...
Ben Caswell Posted March 28, 2017 Report Share Posted March 28, 2017 Were the rings gaped correctly before fitting to the pistons? Link to comment Share on other sites More sharing options...
Guest Posted March 28, 2017 Report Share Posted March 28, 2017 Hello Darren. An interesting thread. In simplistic terms it's either 4x bad bores or 4x bad rings. With an ever decreasing fan club, far & wide, for County parts I think suspicion must fall on the rings and perhaps all having a defect from the same batch. It may be worth giving FW Thornton a call and seeing if they have received news of such or just to get an observation from them. I find they are an excellent outfit and always happy to help with such issues. Your credentials are sound, so you will not be going in blind by pitching such a question should you decide to give them a shout. http://www.fwthornton.co.uk/ Best wishes. Richard. Link to comment Share on other sites More sharing options...
Clive Posted March 28, 2017 Report Share Posted March 28, 2017 Was the block decked at all?? Gasket all seemed to fit the bores OK? Very odd to have 4 top rings break. Why the top ones?? AFAIK they are all the same (save the oil control rings) soI would be suspecting something hitting, and looking for witness marks. Likewise did they all break in the same place relative to the bores?? The trouble wit county stuff is you don't know who the manufacturer is. I know the crank bearings are made by King, who make good bearings elsewhere. but the Triumph ones are not great, even the HD/LC type are not a touch or proper vandervell. Link to comment Share on other sites More sharing options...
JohnD Posted March 28, 2017 Report Share Posted March 28, 2017 You think you have problems? John Link to comment Share on other sites More sharing options...
Darren Groves Posted March 29, 2017 Author Report Share Posted March 29, 2017 You think you have problems? P1000258.JPG John Ok, you win! How did you manage that? Ben - Yes rings were gaped. Clive - No, I didn't get the block skimmed, just checked for flatness, but that could certainly be the reason for the failure between 1&2. This engine was troublesome from the off, partly because a well known Triumph supplier who sold me the Newman Camshaft gave me the wrong settings so it was running 5° out for some time. That aside, it run hot for a while when new then settled down, done a few compression check in it's first year as I was trying to fix what wasn't the smoothest idle (not knowing the camshaft was timed wrong) and they were all good, so the broken rings didn't happen in the first few thousand miles. Compression started to drop a couple of years ago, I noticed the crankcase pressure was high. Richard - I have spoken to FW Thornton's before when I was trying to source some NOS pistons for the engine that's just gone in. I always use a guy called GBH Spares down here in Devon, he holds shed loads of NOS engine parts and companies like Thornton's often go to him to get there stock. The new engine has County pistons in BUT the rings were swapped with a set that GBH Spares have made as they don't trust the County ones, so even some of the traders are aware of quality issues. I did also have the block skimmed this time and the cylinders lined so it could go back to standard pistons, and the Fast Road camshaft has gone and replaced with a MK3 Spitfire one, so hoping it'll be smoother and last a little longer....time will tell. Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 29, 2017 Report Share Posted March 29, 2017 my first car a 53 side valve mk5 Minx had broken rings , the previous owner had used his bicycle clips to fit them !!!! after a rebuild with washers under the valve springs and a carb from a unkown fitted to a sunbeam talbot race car head and manifolds she would pull 7k and tear diffs and halfshatfs then one day bang the crown popped off no3 but the rings were OK Ha ! well its raining Pete 2 Link to comment Share on other sites More sharing options...
Ben Caswell Posted March 29, 2017 Report Share Posted March 29, 2017 Another possibility of the broken rings could be the result of pinking but it does seem the original rings seem to have a dubious reputation? Link to comment Share on other sites More sharing options...
dave.vitesse Posted March 29, 2017 Report Share Posted March 29, 2017 my first car a 53 side valve mk5 Minx had broken rings , the previous owner had used his bicycle clips to fit them !!!! after a rebuild with washers under the valve springs and a carb from a unkown fitted to a sunbeam talbot race car head and manifolds she would pull 7k and tear diffs and halfshatfs then one day bang the crown popped off no3 but the rings were OK Ha ! well its raining Pete And the present day boy racers think they are the first! Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 29, 2017 Report Share Posted March 29, 2017 dave forgot to add twin 2" copper tail pipes fitted to a remember these 'Peco exhaust Booster ' you could drop a cog and take on a PA Cresta with ease it was also Bright red must dig out a picture and on £2 9s 3d a week as an apprentice you had to get out and get under guess when i bought the car for £65 in 1963 i might have been on £4 11s Whohooo 1 Link to comment Share on other sites More sharing options...
dougbgt6 Posted March 29, 2017 Report Share Posted March 29, 2017 My first apprentice pay packet was £3 19s & 6p, much more than Pete's but then I'm MUCH younger. My first car cost £10 but realizing it was a bitza, and at my father's insistence, I sold it a month later for £15. A good profit, I should have stuck to the motor trade. David Attenborough, the famous naturalist, had two brothers, Richard the famous actor and John the auto trader. Guess the wealthiest! OK John was an executive at Alpha Romeo. 1 Link to comment Share on other sites More sharing options...
dave.vitesse Posted March 30, 2017 Report Share Posted March 30, 2017 No money and an old car, plus being in engineering training was the way most of us old's learnt how to keep a car on the road ourselves. And have some fun doing it. Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 30, 2017 Report Share Posted March 30, 2017 should get a boat....we /I have drifted again Pete 1 Link to comment Share on other sites More sharing options...
dave.vitesse Posted March 30, 2017 Report Share Posted March 30, 2017 Well Pete, this is what makes this forum relaxed and friendly. Thanks, Dave Link to comment Share on other sites More sharing options...
thescrapman Posted March 30, 2017 Report Share Posted March 30, 2017 You need to remember that rings fitted to County pistons are not the same as County piston rings, they come from different manufacturers. The separate rings are apparently much better quality, from an Israeli company? Link to comment Share on other sites More sharing options...
Colin Lindsay Posted March 30, 2017 Report Share Posted March 30, 2017 Bicycle clips?? What are they??? 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 30, 2017 Report Share Posted March 30, 2017 You dont need them if you wear a kilt pete Link to comment Share on other sites More sharing options...
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