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