Wanted: Orphan A7 Piston Ring

[RichardL]

I'm wondering if anyone has one orphaned +.040 A7 compression ring. It could be used but I am looking for one that hasn't been filed for adjusting the end-to-end gap. My purpose is to determine how much gap to expect if I decide run with new rings and piston excessive clearance.

Richard L.

[Triton Thrasher]

Being used gives a ring a bigger gap.

There's no need to worry about ring gap in a worn bore, if you can stand the piston slap.

[muskrat]

G'day Richard.
I've more than likely got one, will look tonight.
The problem with new rings in a worn bore is flutter. The expansion & contraction means the ring doesn't seal well and if reved too hard (A7's like it) can break.
Cheers

[RichardL]

Muskrat,

No intention to run this ring. I was just looking to see what the gap will be after over-honing the bores. I don't want anyone to give up a ring they could ever use or sell. Looking forward to your comment on my knurling idea (even if you do hold the power to de-register me from the forum).

Richard L.

[muskrat]

G'day Richard.
I have a new comp ring for a 67mm bore (std BSA/Tri tripple, I used these pistons in the A7SS racer). Your welcome to it. I've lost your address so PM me and I'll post on Monday.
Knurling pistons was quite common back in the day. OK for a quick fix to last a few thousand miles. The knurl will wear faster due to it's smaller surface area but will hold more oil and not wear the bores as quick. The main thing I'd want to rectify is any bore taper. Hone the lower part of the bore to match the top. Std ring gap is 8 thou for an iron head A7 and 13 for the SS, anything under 30 will work if their well spaced.
Cheers