Piston ring groove depths ?

[stevieturbo]

Any do's or dont's here ?

The current pistons seem to have fairly shallow grooves compared to other pistons Ive used. I've a new/old set of rings I bought a few years ago and didnt use for other pistons. Same bore size, same height of ring etc.

But the ring depths are different. ( Totalseal Gapless top )

Approx...top ring measures about 3.9mm deep, groove is about 4mm deep.
Second ring is about 4.15mm deep, groove is about 4.35mm deep.

Rings that were supplied with the pistons were about 3.65mm and 4mm deep respectively ( again from memory would need to measure and write down exact )

Older pistons I've had, never measured groove depth until now, some are as big as 5mm deep. When buying rings, groove depth is something I've actually never been asked for.

And no, piston supplier is a ballbag and has stolen my money so despite having paid for new rings via him...seems they arent coming.

And the piston maker Diamond....seems they havent a clue what emails are, as they seem incapable of responding.

Obviously the ring should never be fully recessed into the groove...but how much back clearance should there be ?

[stevieturbo]

PeterBurgess said:

I was struggling to get some oil ring support rails for some Diamond V8 pistons, in the end I sourced them from
http://www.performanceunlimited.co.uk/ who were most helpful.

I hope this helps as I guess it is best to run the designated ring pack.

Peter

I have plenty of support rails, and any rings I've bought in UK have always been from Dave, including the ones I wish to use now.

Just the groove depth seems very shallow. Diamond have finally replied so hopefully they can give me a definitive answer.

[stevieturbo]

Pumaracing said:

This is going to be fun. I'm dying to see how much they know before I give a full analysis of this issue. You have email btw.

no email received as yet.

The only issue as such...is the original parts supplier being an asshole and stealing my money

The rings Diamond supplied obviously fitted, I now wish to use some rings I bought a few years ago for different pistons but never used as plans changed.
But they are same 1.5, 1.5, 3mm ( plus oil support ) and for same bore size.

But measuring various pistons I've had and used over the years, ring depths seem to vary massively.

Very interested to know why ! and what is better or what cannot be done.

[stevieturbo]

When you refer to a vertical groove gap on a piston....what are you referring to ?

Also I hear you about there needing almost no back clearance...but should there be any allowance for a carbon buildup behind the ring, which is bound to happen over time ?

[stevieturbo]

Pumaracing said:

I'd be interested to know the nominal bore size and the piston top land diameter. Also the aluminium alloy if you know it. 4032, 2618 etc.

Would need to measure piston for ring land diameter, but here are stats supplied.

Diamond have also said that the rings I have here would be fine to use.

[stevieturbo]

Pumaracing said:

I expected them to cop out with "if it isn't our stuff we can't recommend it". Kudos.

Best I can measure is the OD of the piston at the height of the top ring is 100.71mm, 3.965"

The new rings finally arrived from the US supplier...the same rings he said they got into stock back in October 2014 for me...the same rings that have a date sticker from Total Seal for the top rings of 19 Feb 2015.

It lists top ring depth as 150thou ( 3.81mm ), so no doubt it's the same as the ones I have here anyway, although I dont have the packaging of the others to compare part numbers