Lister Engine Forum
General Category => General Discussion => Topic started by: cat rat on June 08, 2020, 12:12:20 AM
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Hi all first things first i do not spell good now iv got a problem with sr 1 the engine had a bag knock on it when i removed the hed the piston was and stil is hitting the hed iv re shimmed the hed so the clerins is .37 with the led a cros guginpin but the piston is still hiting the when running this i no as removed the hed a gain now iv got a nuw hed set and iv put all shims in plus 3 more 003 shims but the same thing piston still hiting the hed when running the piston is very prowed of the cyilinger wher the piston is hiting is from the conbustion chamber on the piston on the push rod side and in between the valvs on the opesit side am am well over on the shims taking the clerence to .45 a cros guginpin but the valvs do not tuch piston do you think piston is not sqer or a con rod problem iv also chaing the big end can you give avice on this this engin has got my beet
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Hello cat rat: You mention the piston hitting the head when running. Have you tried turning the engine by hand? Seems to me if the piston is hitting the head you should not be able to turn the engine over by hand when the piston comes up the head.
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yes the piston is defenetly hinting the hed wen ruining but ont wen turning by hand there is two marks on the piston and hed wer hitting sumthing is not rite with it at all i never had this be for on an sr iv been building engines most of my life workt as plat fitter this got me beet
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There's obviously vertical movement somewhere which is only apparent when the engine is running. I'd say there are three places it could be:
- Big end bearings (but you've done them already)
- Little end bearings (seems unlikely you'd get 0.040" play and not be able to detect it by rocking the engine back and forth)
- Crank bearings - allowing the entire crankshaft/rod/piston assembly to move up & down. This would be harder to find due to the weight of everything, but should be fairly obvious, if you try to lift the engine up by the end of the crankshaft (if it's available, I don't know much about the SR engine). I'd also expect the engine to be jumping around all over the place, if it had that much vertical play...
It has to be movement between the physical components; if (for example) the rod were too long, it'd hit when you turned it by hand. Same with an over-tall piston, or an excessive stroke on the crankshaft.
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Well cat rat: It sounds like you have worked on Listers before so you are aware they are very noisy engines. All kinds of clatter, cracking and knocking.
Sometimes we see something and decide that is the problem but in the end it turns out to be something else.
Here is a list of things that can cause knocking. A loose or wore out main bearing. a loose flywheel, injectors set too early, too much crankshaft end-play, a sticky valve and carbon build up on the piston.
The crankshaft end-play should be between 0.005 and 0.009.
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I see that I forgot to mention I got that info from a LR/SR booklet I got when I purchased a SR awhile back.
I was thinking that out of those possibilities extreme end-play might cause a piston to rock enough to hit the head.