Unorthodox re ringing of a 289 question

[starman321]

I'm restoring a 69 Mustang which has a 289 in it but should be a 351 so I don't want to put a lot of money in an engine I will replace when I find the 351 to rebuild. 289 had bad valves won't start so pulled heads to grind etc. Plugs were burning light brown so thought since had heads removed I'd re ring (normally would bore and use oversized pistons etc if I was keeping the engine) so since the end gaps on rings were excessive I went with .020 over rings in a standard bore to get back to the correct end gap. Well that was ok till I came to the oil rings with the expander. I filed the correct end gap in the oil rings but what do I do about the expander. Thought I'd just use my old standard ones but thats a little scarry and a couple are broke. Anyone have any thoughts on this. Could just buy some standard rings and start over but already have a day into gaping all the compression and oil rings plus by doing the .020 oversize rings my end gaps are much better than standard rings. I'm scratching my head on this one.

[GreenV8S]

starman321 said:

.020 over rings in a standard bore to get back to the correct end gap.

Are you saying the bores are worn 20 thou oversize? I suppose as long as you gap the rings correctly it won't matter if they're oversize.

You should have an upper and lower rail and an expander. The expander doesn't need to be gapped as such but should be sized to fit so that the ends butt together properly and don't overlap.

[stevieturbo]

Sounds like you need to have someone who knows what they're doing build your engine ?

You just decided on a whim to change the rings for no real reason ? Seems odd.

So what exactly where the ring gaps and why did you deem them excessive ?

And buying incorrect rings expecting them to fix whatever problem you thought their was....seems a bit odd, vs buying the correct rings.

[PaulKemp]

It’s a make do and mend build until the right engine is found.
I’m not sure I would go to all that trouble but as the OP has got this far surely the expander ring can be persuaded in?

[Mignon]

You will have to file the expander too. I suggest very carefully against the side of an angle grinder disk or grinding wheel. It's not the sort of thing you can do with a metal file.

You say you are using + 0.020" rings in a standard bore. I trust you are aware that rings need a certain minimum gap to allow for thermal expansion when they are hot or the ends will butt up and the rings will break. For a stock or mildly tuned normally aspirated engine that minimum would be about 0.004" per inch of bore diameter.

[Mignon]

BTW, The minimum ring gap must be set in the smallest part of the bore that the rings travel to and just because there is a lot of wear at the top doesn't mean there will also be lower down.

[PeterBurgess]

Maybe the OP has Grant-type oil control rings where the expander has a raised part at each end to prevent the expander riding over itself and taking the tension out or the rings. I suppose he could shorten the expander and bend the expander to suit but the expanders do seem a little brittle to me. The Grants expanders have red paint on one and green paint on the other raised part to draw attention. We have seen a lot of engines burn oil because the expander has been fitted incorrectly, either snapping off the raised nib on one side or even fully overlapping.

[TooMany2cvs]

If the bores are that worn that oversize rings are needed (instead of just non-shagged ones), then won't the standard-size pistons (presumably similarly shagged) be a bit wizard's sleeve?