Oil support rail gap

I had my rings gapped by the machine shop that bored and honed the engine and checked them when it all came back. I also checked the oil rings but they were all well over spec.

Today, I started putting rings on the first piston. This also included an oil support ring which came from a separate bag in the box. It wasn't until I looked at the rings I suddenly thought to check the support rail gap. The oil rings should be at least 0.015" IIRC, but there is no information with the support rail. What it does say on the bag is 4.032-4.085" which is above my 4.030" bore.

Photo below shows the microscopic gap, right where the light reflects. Do I need to take it off again and measure? And what should it be? Photo further down is of the bag with the specs on.

The only thing to worry about with the support rail is that the ends are butted up, and not overlapping.

Remember, it's in the form of a spring, so "end gap" is a non-event.

Yeah, thinking about it, because this ring doesn't touch the bore, the gap will actually increase with heat.

The ends are not butting up, but the size on the packaging also says 4.032-4.085" and my bores are 4.030". Still not sure if this matters.

Wiseco has come back to me saying that I can't use the 4.032"-4.085" support rings on my 4.030 pistons.

Also, the pistons are actually 4.027" (to fit 4.030" bore), which is the size to go by?

Not something I recall coming across before, thank you for posting the details!

Seems like the chap gave you the wrong expansion rails for the ring set, as you said they were separate, so you'll need to chase him up and swap for the correct ones, or try and make a special order from Wiseco just for those expanders.

Hi Gord,

I had a few follow-up emails with Wiseco, I had misunderstood what they said. The rings are correct, they have just been labelled wrong. Also, the rings come with the pistons, so it's not the shop I bought them from that made a mistake.

Regards,

Henrik Morsing