Big end reshelling

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Waterboard

Member
Joined
Aug 23, 2017
Messages
119
Thought I’d ask what the consensus is on reshelling the big ends and re-ringing engines half way through their lives. 1.7 motor.
Older engines tend to love it as you get less blow by past the rings and the oil pressure goes up and that generally keeps it all happy for longer.
Nick silicon carbide plated bores are as hard as a coffin nail so re-ringing tends to work well on most motors but I’ve never renovated this kind of engine on a budget and I’m being asked to work on one.
Any pitfalls, problems or general shitstorms to avoid??

Thanks.

J
 
Thanks,

Regretfully not of any use, linering is a terrible idea but thanks for the pointer.
Some motors respond to new parts and some don’t - someone out there must have some experience????

Thanks...
 
Quite a few people have successfully linered the 1700 Puma engine, a few FRP’s too as the proper alternatives from Ford are no longer available. Cost wise they were not too bad either. For example, I have the last set of Ford piston rings in existence sat in the parts hoard, at full price they were £113 per cylinder at the time....

Alternatively there are some big end shells from a suzuki that are near perfect fit. The exact details are here...

https://www.projectpuma.com/viewtopic.php?f=64&t=26486&p=361287&hilit=Suzuki+liana#p361287
 
Waterboard said:
[post]366846[/post] Thought I’d ask what the consensus is on reshelling the big ends and re-ringing engines half way through their lives. 1.7 motor.
Nick silicon carbide plated bores are as hard as a coffin nail so re-ringing tends to work well on most motors but I’ve never renovated this kind of engine on a budget and I’m being asked to work on one.
Any pitfalls, problems or general shitstorms to avoid??

Thanks.

J

As already said, there are no piston rings available anymore for this engine, so you would have to get creative about it. Basically, you have two options: either to machine the pistons that would enable them to take ANY rings you can get, or to mix and match the ones that are in existance.

There is a guy (falsely) advertising on eBay a NPR set 79 7643 0000 (for Honda A18 engine) as set for puma engine. It does match dimensionally (bore 80 mm, 1.2, 1.2 and 2.8 mm thickness) but the material selection is not suitable. The 1st and the oil scrapper rings are chromed and that is not good match for nikasil liners. The rings for piston liners should be nitrited.

So there is another set for Nissan QG18 engine, also NPR 79 9084 0000. It is also 80 mm bore, and it's rings are: 1.2, 1.2, 2.5 mm in thickness, and the 1st and the oil scrapper are nittrited as they should be.
The problem is that the oil scrapper is too thin. So, my suggestion would be to take the 1st compression ring from Nissan set, the 2nd one from Honda set and leave the oil scrapper original as it is. That should be better than it is now by miles in terms of compression leakage and the materials would be ok. The alternative for the 2nd compression ring would be a set for Rover K series engines 89 0623 0000 (again, a NPR PN) which is exactly the same as the one in puma (material, dimensions and shape). It is worth noting that this set from Rover is very close call in general, but the 1st CR and the oil scrapper are sadly to thin.

So it is: the 1st compression ring from a Nissan set, the 2nd either from Honda, or Rover set (I would suggest the Rover one!) and just reuse the oil scrapper from Ford.
With the big end shells from Suzuki (already given link in previous post) that is as budget as it can be.

If you do machine the pistons, just bear in mind to go for a set of piston rings that are materially compatible with nikasil. The other option is to get custom made a set of piston rings, but I am not sure how much that would cost
 
Well, don't shoot the messanger! I am just pointing out that there ARE options available.
Which made me think, now. I guess the thickness of the oil scraper is dictated by the meshed centre piece (the oil scrapper is 3 piece design) which is NOT a wearing item as it is not in contact with cylinder bore. So, by taking the 3rd ring from the Rover kit and mixing it with the puma center piece you would end up with desired thickness and renew all the piston rings on this engine making it basically a new one....!
 
Boys...

Nippon Piston Ring corporation were making kits up until at least 5 years ago.
I have several sets purchased when I realized engine parts were becoming scarce. 80mm piston, OEM quality.
Work well with replated bores, no failures after 30k miles in a very mildly stroked a 1.7 motor, gave good results but that’s another story.
I was expecting possible blistering of the plating but all good so far...
 
If there is a kit out there, amazing! The part numbers would be great if you can.
 
Wild E. Coyote said:
[post]366895[/post] Well, don't shoot the messanger! I am just pointing out that there ARE options available.
Which made me think, now. I guess the thickness of the oil scraper is dictated by the meshed centre piece (the oil scrapper is 3 piece design) which is NOT a wearing item as it is not in contact with cylinder bore. So, by taking the 3rd ring from the Rover kit and mixing it with the puma center piece you would end up with desired thickness and renew all the piston rings on this engine making it basically a new one....!

You deserve a medal, Sir.

I have been searching around in Piston ring catalogues and also saw the one at eBay that i assumed it was for the Honda A18 engine.

Thumb up :grin:
 
Hi
Sorry to drag this thread up again. I was looking at replacing rings on my engine and was looking through the latest NPR catalogue and am a bit confused, you state that the rings need to be nitrated to be compatible with the Nikasil liners but not all the rings listed in the kits you say can be used are not showing as nitrated! Or am I missing something?.
 
You misunderstood: I said (actually, Mahle did) that you can use pretty much any pistong ring, but NOT a chromed one. So that is the one you should avoid.

Hope that helps
 

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