Joined: Mar 2022 Posts: 15 Threads: 4
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Location: Bristol
Car type: Austin 7 Ruby 1936
I’m after a little advice.
I’m about to remove the pistons as part of some engine rework, will I need to replace the piston rings or can they be reused? Obviously if I find that they are damaged in anyway I will replace them, but if they look ok can I just leave them alone and save myself a few £?
Thanks in advance,
Luke
Joined: Aug 2017 Posts: 3,394 Threads: 106
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Location: Darkest Bedfordshire
Luke, there are only really two ways to know the answer to this question:
1. Do a compression test - having said that, A7's can run pretty well on compression levels which nothing else would tolerate.
2. Measure ring gaps/ bore taper and ovality and try to guess whether it is ready for a rebore (which may be glaringly obvious, or perhaps more subjective).
Was it running OK before stripping? Any signs of oil smoke in the exhaust? If it was running well then I wouldn't replace rings as a matter of "routine". You might do well to check whether they are even available before making a hasty decision.
Joined: Mar 2022 Posts: 15 Threads: 4
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Location: Bristol
Car type: Austin 7 Ruby 1936
Great thank you. It wasn’t running well but that was down to a lose big end bolt. I managed to catch the problem before the engine self destructed.
I’ve never delved this far into an engine before and didn’t know if they could be reused or had to be replaced every time a piston was removed.
Many thanks
Joined: Aug 2017 Posts: 613 Threads: 19
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Location: Hampshire UK
Hi
At risk of stating the obvious, put each piston back in the bore it came from and with the small end bolt head facing the same way it was when removed. Keep the rings on the pistons, they are fragile and removal always risks breakage. Not sure how you can get a loose big end bolt, they are supposed to have castellated nuts with split pins or modern nyloc nuts. I would suggest a torque of 20 to 25 foot-pounds with dry threads but opinions vary on this. Have a good check for anything else loose or incorrect.
If you have stripped this far, a clean up of any carbon and a light valve grind (lap) is probably worthwhile.
If the rings do need changing at some time in the future, the knowledge you gained during this strip down will speed things up !
