Quick Piston Ring Gap Question
 

Hey guys, I'm working on doing my ring gaps right now, but I just want to make sure I'm on the right tack. I have a B18A1 block that has been bored & honed to 81.50mm. I have new RS Machines 81.5mm ITR pistons and Hastings rings as well.

So far I have measured all the gaps as the rings came out of the box, and here's what I got:

Cylinder 1:
Top Ring = 0.015"
Second Ring = 0.012"
Oil Rings = 0.021" & 0.022"

Cylinder 2:
Top Ring = 0.015"
Second Ring = 0.010"
Oil Rings = 0.020" & 0.020"

Cylinder 3:
Top Ring = 0.017"
Second Ring = 0.017"
Oil Rings = 0.018" & 0.019"

Cylinder 4:
Top Ring = 0.017"
Second Ring = 0.015"
Oil Rings = 0.018" & 0.021"

Now here's where I need a little clarification. The only spec given by Hastings is the MINIMUM gap for the top ring. It says 0.004" per 1" of bore, so for 81.5mm, that's 0.0128". I'll just call it 0.013". Hastings doesn't give any specs for the other rings, though.

The service manual gives these specs:

Top Ring = 0.008" - 0.012" for Teikoku rings
or 0.008" - 0.014" for Riken rings

Second Ring = 0.016" - 0.022"

Oil Rings = 0.008" - 0.018" for Teikoku rings
or 0.008" - 0.020" for Riken rings

So, according to the factory specs, my top ring gaps are too large, but they're still only 2 to 4 thousandths larger than the minimum given by Hastings, so I think they're okay.

The second rings gaps are all a little small. Should I file them to the middle of the factory spec range, or towards the upper end of the range since I have a slightly larger bore?

The oil rings are all near the upper end of the factory spec range. Should I just leave them as they are?

Thanks guys, any clarification you can give would be great! This is my first time doing rings so I just want to be sure I'm doing it right.

Thanks!

Re: Quick Piston Ring Gap Question
 

I found some useful information from Wiseco. http://www.aa1car.com/library/ringendgap_wiseco.pdf

I think I'll go somewhere around the performance street/moderate street turbo specs. That would give me a minimum top ring gap of about 0.015", and a minimum 2nd ring gap of about 0.018".

Since some of my top rings are at 0.015" and some are at 0.017" right now, should I bring the smaller two out to about 0.016" just so they're more consistent between cylinders?

What do you guys recommend?

Re: Quick Piston Ring Gap Question
 

2nd ring should be .002 to .004 looser than top ring
oil rings should be a minimum of .015
at least this is what i do and it works perfect 99% of the time.

Re: Quick Piston Ring Gap Question
 

Id also make the ring gaps the same or as close to same as possible on all 4 cylinders.
Ideally you want a perfectly even running engine from cylinder to cylinder...

Re: Quick Piston Ring Gap Question
 

gaps will vary by manufacture... OEM rings use OEM gaps, and aftermarket manufactures have their own gaps. its no different that piston manufactures, like those with heavier silicone content tend to have a larger piston to wall clearance when compared to factory, etc.

Re: Quick Piston Ring Gap Question
 

what does rs machine recommend?

Re: Quick Piston Ring Gap Question
 

Alright, I'm just gonna go to 0.017" on the top rings just so they're all the same, and then I'll go 0.019-0.020" on the second rings.

Thanks guys!