DDK - Die Deutschen Klassiker

Morning all!!

I'm fitting new piston rings to my 356 T5b super90, I've read as much as I can about it but still feel quite nervous(!!)

I've deglazed/honed the barrels, they've come out well and ready to use, can someone please talk me through the fitting of the rings, position of gaps etc?

I have the three rings and believe it's oil ring top and the other two 90 degrees but is that from each other or from the oil ring gap? (ie; 10 'clock and 2 0'clock or 9 0'clock and 3 0'clock!!?).
Any other advice/tips very gratefully received.

Thank you and happy sunday tinkering!!

Hi the idea here is to minimise oil and compression loss due to leakage through the neccesary ring gaps.
It sounds like your cylinders are ready and that you know your pistons and cylinders measure to spec including the ring groove width .You need to check all the ring gaps next.
To do this each ring with the exception of the oil control spring part needs to be slid into its cylinder to about 1\3 depth from the top , use a piston to get it in square. You now need to measure the end gap with feeler gauges and compare what you have with the engine spec. If the gap is too big your cylinders are worn and you need to recheck their size and whether you can use them. If the gap is too tight the end of the ring needs metal removing carefully to establish the correct gap. This can be done with a high quality fine file or better a very fine wet stone or if you have one a special tool. I use a wet stone lubricated with oil and have a simple little clamp to hold the ring square to the stone. The second and comp rings are quite delicate so take care. Once all the gaps are set keep the rings with the cylinder they match..
You are now ready to fit the rings. They have a right way up which the supply instructions should detail. A rule of thumb for the top two rings is lettering or step features up but you must be sure.
Usually the oil ring pack is 2 or 3 piece, a springy or wobbly ring and 1 or 2 scrapers which go over or along side the spring. The springy bit goes on first I always put the join at 6 o'clock, next the scrapers usually one either side of the spring, I put the join for this at 12 oclock . next the second scraper I place this at between 3 and 4 oclock, finally the top compression ring join I usually place between 9 and 8 oclock. All this viewed from above the piston relative to the inlet.
I prefer to open the rings with my hands but tools are widely available to make this easier especially with very tough rings.
When using the ring compressor to fit the pistons take care to keep the ring joins where they were set.
I have never noticed ring join position when stripping an engine to understand if they do move during use but one the two strokes I ve built the rings are often pegged to stop them moving and interfering with ports in the cylinders. I will look next time I have a Porsche motor down.

Hope that helps .

Andy

Edit, I re read and noticed you have a one piece oil ring . that fine just older technology. The join still goes at 12 o'clock viewed top of piston relative to inlet with the 2 comp rings either side at 4 and 8 respectively. Some folks will do this slightly differently I'm sure, but essentially you are trying to eliminate the leak that would occur if the ring gaps were all lined up.

Hi Andy,

Thank you for taking the time to reply and for such good instructions!!
Very much appreciated... I'll let you know how I get on!!

Thanks again.

RR65