piston ring gaps ???

steptoe · Post by **steptoe** » Mon Apr 28, 2008 2:20 pm

on checking the ring gaps in my newly bored out blocks I am getting between 0.5mm and 0.55mm (former is not tight, later won't fit)

on std bore on EA81 the gregorys says max of 0.35mm

the ring maker Grant say 0.003 min (race) per inch of diameter of bore , in my case about 3.75 inches to max of 0.004 per inch if bore dia. which is 0.29mm to 0.38mm

the rings are gong back for swappin'

littlewhiteute · Post by **littlewhiteute** » Mon Apr 28, 2008 6:42 pm

steptoe wrote:on checking the ring gaps in my newly bored out blocks I am getting between 0.5mm and 0.55mm (former is not tight, later won't fit)

on std bore on EA81 the gregorys says max of 0.35mm

the ring maker Grant say 0.003 min (race) per inch of diameter of bore , in my case about 3.75 inches to max of 0.004 per inch if bore dia. which is 0.29mm to 0.38mm

the rings are gong back for swappin'

.003 - .005 per inch of bore is the accepted norm. towards the low end for street, towards the high end for race.

So if you have say .52 (20.47 thou), I'd say too much.
Have you measured piston to bore clearance yet?

steptoe · Post by **steptoe** » Wed Apr 30, 2008 7:00 pm

No. Actually trust my machine shop to have got it right. They had pistons and have unwrapped them all when in for rebore. Do you use feeler gauge either side of piston ? might just be in the gregories The last rebuild i did i used the 3 thou per inch as a guide and had to file thegaps down to suit , and thought i was gonna get away with this task this time !

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Wed Apr 30, 2008 8:24 pm

I like to make my ring gaps a bit more to the lower clearance and generally have been using .25mm for building Subaru motors.

steptoe · Post by **steptoe** » Sun May 04, 2008 9:35 pm

Went back to ask my machine shop guy after finding it difficult to get the right rings - got a boot up the arse for not asking him first - and then got the changes of ring gaps over four decades by different ring makers at different times. So, the rings have returned. At least I don't have to rip the file out!

Reading through the FSM for the EA82 and the 1300 & 1600 engines the maximum allowable ring gap is specified as 1.5mm , not kidding (now feel stupid I didn't consult the bible first)

YouTube · Post by **El_Freddo** » Sun May 04, 2008 9:41 pm

Hmmm... I got my rings, shoved them in and never thought about gap space... Never heard of this problem before or to worry about it.

Bennie