Hi,
I am checking our a spare engine for my P3 - it is the '75 model' 6 cylinder engine - as I may well swap this into my P3, but want to check is in good nick before I go to all the work of an engine swap.
Today I measured the big-end and main bearings using plastigage,
Big-ends were about .003 - which is probably ok
Main bearings were .004-.006 - ok?
So, given that the correct main bearing gap is .002 (yes?), then should I be concerned about my main bearings, and possibly getting the crank reground, new main bearings and all that? I'd prefer to avoid putting the engine in the car to find out in 18 months that it fails, but if these engines are very tolerant of main bearings then perhaps I shouldn't be concerned?
Would very much appreciate some comments & advice from all you folks who have much more experience in these cars than me!!
Regards Neil Henderson
big end wear - what is ok?
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neil.henderson
- Posts: 72
- Joined: Sat Feb 19, 2011 2:15 am
- Location: Murrumbateman, NSW, Australia
Re: big end wear - what is ok?
Hi Neil,
Have you made any further progress with the engine as yet?
The measured clearances of your mains seem excessive although I don't have a great deal of experience in running an engine in a known similar conidition. My engine is with the engineering shop at the minute having the crank polished and bearings checked so I will ask their advice and opinion with regards to your measurements when I speak to them in the week.
It seems that mains are currently obselete so it may be worth having your crank checked/polished rather than ground and getting the bearings re-metalled if you decide to reconidition the unit. I believe that big end bearings are still obtainable.
I'll get back to you once I know more.
Best
Matthew
Have you made any further progress with the engine as yet?
The measured clearances of your mains seem excessive although I don't have a great deal of experience in running an engine in a known similar conidition. My engine is with the engineering shop at the minute having the crank polished and bearings checked so I will ask their advice and opinion with regards to your measurements when I speak to them in the week.
It seems that mains are currently obselete so it may be worth having your crank checked/polished rather than ground and getting the bearings re-metalled if you decide to reconidition the unit. I believe that big end bearings are still obtainable.
I'll get back to you once I know more.
Best
Matthew
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neil.henderson
- Posts: 72
- Joined: Sat Feb 19, 2011 2:15 am
- Location: Murrumbateman, NSW, Australia
Re: big end wear - what is ok?
Hi Matthew,
Many thanks for your reply - it really helps me a lot when I get comments back from this forum..........
Yes, I'm starting to think the crank/bearings are rather more worn than they should be. So, I'm planning to replace both main bearing shells and big end shells - after appropriate grinding/polishing.
But I need to make sure I can source replacement bearings before I start the process - have you managed to locate a source of replacement bearing shells??
Also, very interested to hear the opinion of your engineering shop.
Regards Neil Henderson
Many thanks for your reply - it really helps me a lot when I get comments back from this forum..........
Yes, I'm starting to think the crank/bearings are rather more worn than they should be. So, I'm planning to replace both main bearing shells and big end shells - after appropriate grinding/polishing.
But I need to make sure I can source replacement bearings before I start the process - have you managed to locate a source of replacement bearing shells??
Also, very interested to hear the opinion of your engineering shop.
Regards Neil Henderson