MD1 piston ring compatability.

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ripvan1

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I read somewhere that several old cars had piston rings that are compatible with an MD1 which are proving hard to source. Crom marine (Sweden) seem to have them but their catalogue is showing a blank page so thought I'd check out the classic car route.

Any thoughts welcome
 
There are-or were-several piston ring specialists in the classic car and motorcycle supply business. Also Cluppet Piston Rings would make to your size and specification in plain-IIRC- fine grain grey cast iron.

The important dimensions are the diameter, thickness and radial depth. I have kept many vintage and veteran engines going by sizing the installed gap of oversize rings. This compensated for worn cylinders to some extent.

I once rubbed a 3/16 inch thick ring down to 1/8 inch thich on a mirror and emery cloth for my pre-war racing Triumph 350cc the night before an importand race at Cadwell park.

My fingertips were bleeding afterwards.......................
 
Ardenfour thanks for the offer. It's the bottom oil scraper ring that's broken, so yes I would be very grateful for a replacement. Is it a md1and not md1b as I believe there is a difference?
 
Different bore size on the 1b. I had the MD1, earliest of the bunch. Am off the island next few day but will do a search towards the end of the week ��
 
rotrax said:
I once rubbed a 3/16 inch thick ring down to 1/8 inch thich on a mirror and emery cloth for my pre-war racing Triumph 350cc the night before an importand race at Cadwell park.

My fingertips were bleeding afterwards.......................
Click to expand...

Luxury! I remember when..........
 
x
rotrax said:
There are-or were-several piston ring specialists in the classic car and motorcycle supply business. Also Cluppet Piston Rings would make to your size and specification in plain-IIRC- fine grain grey cast iron.




The important dimensions are the diameter, thickness and radial depth. I have kept many vintage and veteran engines going by sizing the installed gap of oversize rings. This compensated for worn cylinders to some extent.

I once rubbed a 3/16 inch thick ring down to 1/8 inch thich on a mirror and emery cloth for my pre-war racing Triumph 350cc the night before an importand race at Cadwell park.

My fingertips were bleeding afterwards.......................
Click to expand...

Remember spannering for Gary Bryan, the sidecar racer, in the early 70s. Started to do good. Came the Easter Bank holiday it was Darley Moor on the Friday, Croft on the Saturday, Mallory on the Sunday and Crystal Palace on the Monday. Gary and the rest went in the Thames van, towing the outfit in a cut down Thames van made in to a trailor. I went in my Mini Cooper 997 because my bro and his wife wanted to do the tour. The only prob was that the 997 had tiny discs on the front with tiny pads. They didnt used to last long!
Got to Mallory and the familiar sound of worn out pads was heard. What to do now? Looked at the outfit spares, we were using early disc brakes and I realised that the pads could be cut down to fit. Hacksaw and file and away we went! They worked! Better than the BMC ones!
S
 
Nice one!

I lived just down the road from the Palace and would catch the 137 bus to the races there before I got a motorbike.

I rode in the last ever meeting at the Palace-'73 or 74 IIRC-shame it went.

It was bloody dangerous though............................

Getting back to the OP, F. W. Thornton usually found what I wanted. Giving model of engine was not always the best way though, the bore size required plus thickness and radial depth often got results. Dont forget that if only O/S rings are available filing the ends to give the correct installed gap will often work very well.

After all, we are not talking 18,000 RPM, 100 BHP highly stressed engines here............................................
 
ghostlymoron said:
"The important dimensions are the diameter, thickness and radial depth."
Does anyone know these figures for an MD1?
Click to expand...

The diameter required will be the bore size plus any oversize caused by reboring the cylinder.

The thickness can be measured from the old ring-or rings-and the width of the ring groove.

The radial depth is how deep the groove is in the piston.

So-using a piston,or the old rings and a vernier it should be pretty straightforward to work it out.

If measuring old bits the measurements will not be absolute as the rings will have some wear and the piston will have been made with some clearance for the thickness and radial depth, but it will not be that difficult to work out what you need to order.

If an old British unit measurements,apart from bore size, usually will be Imperial, a Volvo almost certainly metric.

Good Luck with finding what you need.
 
I've just done all that with fwthornton and I now have a scraper ring in the post. Whoopee. Measurement for this ring is 0.181 x 0.181 x 3.12 11 quid
 
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