Hello all - I've recently joined the club and am restoring an A65T. I'm sure i read somewhere that it was possible to borrow tools - can anyone either point me in the right direction or else tell me if there's an easy way to compress piston rings when putting the engine back together, without using a special tool?
Thanks!
From bitter experience - no nothing works as well as a set of ring compressors.
The good news is they are cheap, a pair of 70-75 mm of the type for bikes will cost you £20 plus post if you shop around. The bad news is you are sure to need them again :)
When you've got them post on here and we can give you the warts and all tricks to using them. Did this job yesterday.
If you are fitting modern Hepolite rings they take quite a bit of compressing.
A large reusable cable tie.
Hi,
I make ring compressors out of beans tins and Jubilee clips.
Dave.
Yep, and as a last resort a scriber and terminal screwdriver.
Thanks for suggestions - i didn't think of a baked beans tin! I'll try that first and get the proper ring compressor if i can't get it to work.
Cheers, Mike
I've put an A65 together with fingernails and a small screwdriver, but that was with old rings and I'd never do it again. The modern rings, especially the multi-piece oil rings are a lot stiffer and you need a good fitting compressor.
The Hepolite rings are now £45 a set.
well said,
piston rings are cast iron and quite brittle.if you brake one ring another set is needed.
2 piston ring clamps and clean oil to ease them down is my recommendation.
Fitting cylinders to the engine (two pistons at once) is not at all easy without ring compressors. The way I used to do it, before getting the right tools, was to detach the pistons from the rods and put the pistons in the cylinders individually, then lower the whole lot onto the conrods and then insert the gudgeon pins and clips. It's not exactly easy but easier than doing it the other way.
Hi,
Rather than risk a clip dropping down in to the cases use two strips of wood across the case and rotate the engine until the pistons are sitting on them. This gives a stable position for lowering the cylinders over the pistons. Although it can be done solo, a second person is useful. Keeping the cylinders square and gently lowering them the ring clamps will be pushed down. Never use for or any impact. If the cylinders are reluctant to go down then check that the rings are entering the cylinder.
This is were the second person can help. A gentle push with a screw driver will ease the ring in.
Once all the rings are in remove the clamps, lower the cylinders, remove the strips of wood and fasten it all down.
I have noticed that A65 bores seem to have a slight taper at the bottom to give a slightly larger bore at the base. This helps greatly with getting the rings in.
Dave.
Quote from: JJC on 20 May, 2026, 18:56 Fitting cylinders to the engine (two pistons at once) is not at all easy without ring compressors. The way I used to do it, before getting the right tools, was to detach the pistons from the rods and put the pistons in the cylinders individually, then lower the whole lot onto the conrods and then insert the gudgeon pins and clips. It's not exactly easy but easier than doing it the other way.
...... This was the way I used to do it without ring compressors...
If the cylinder has been bored its worth taking a stone and taking any sharp edge off the bottom of the bores and putting a small chamfer on.
for me, the method depends on how heavy the cylinders are. norton barrels are heavier than bsa or triumph ones.but the weight can aid sliding down the ring compressors.
however , if you use the pin clip method with piston rings already fitted method you can get caught out by the circlips not engaging properly with pattern pistons.the last set of jc pistons i fitted had slightly longer pins which i had to grind down so the circlips sat properly.
i ve seen plyboard cut with a slut for the conrods as a base for holding the pistons while sliding down the barrels, and dont forget the base gasket goes on first.