Gents, looking for advice on best ring gap for 73.5 GR race pistons,

I am using Total Seal Gapless top ring set, which contrary to the name require ring gap clearance set.



Thanks in advance

Mal

We recently tried one of Graham's 72.5mm Nippon top rings in a fresh bore, gap was .008".

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

So is 8thou the best ring gap or is that just what you are stuck with unless you want to make it bigger?

Also Mal, i admit to being curious about the total seal gapless rings after seeing an advert for them, as to how they are gapless. Are they just standard design?
Perhaps it's worth contacting them about what they recommend for the gap if they are a different design to normal.

I would not like the gap to be less than .008" on a 1275's top ring. You need to allow for expansion when HOT.
Hastings top ones typically are .013"- .014".

[edit] I was not sure how so-called`gapless' rings work, however after reading this blog, it is clear one type works similar to the `Cord' brand rings used for re-ring rebuilds back in the 50s and 60s.
They do in fact have a normal gap, but there are 2 narrow section rings in the one groove, with their 2 gaps staggered.

A second type, Total Seal have the ends notched (only 1 ring in the groove) so the gap is Z shaped when assembled.

https://www.highpowermedia.com/blog/307 ... pless-ring

also see
http://performanceforums.com/forums/arc ... 39283.html

http://015ef8d.netsolhost.com/TechPage. ... sPistRings

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Matt , as doc has described they have two top rings in the one groove , main ring with a smaller ring that sits in a groove, with ends opposing they give a 100% seal, I will be back home tomorrow I will take some pictures.

I purchased rings from Calver Special Tuning in UK, I have asked for his advice on gap as well.

Thanks for your advice doc, I think 8 thou will do the trick

Mal

Keith Calver has recommended that I stick with clearance as stated in the blurb that comes with the rings , 0.0065" for the top ring and rail, and 0.0055" for the second ring, he has never had any issues.

M