20B compression testing
 

What should compression bump up to on these engines, using a regular compression tester?

Also, what does it mean if I get 2 even bumps, then the 3rd is low but not zero (about 35 psi)? Stuck seal, bad seal?

oops sorry about the double post, don't quite know how that happened.

come on guys, im sure someone can answer this?

hhmm....I don't have personal experience with 20B's but I would assume you'd want to see about the same as any other rotary. Ideally over 100psi, Mazda considers anything over 85 to be good. As for just one face low, that could be a side seal.
-John

you think side seal because it is just one low face right. Because if it were an apex seal it would be low on 2 faces.

So if it is a side seal, I would guess it is just sorta stuck from sitting as I have never heard of them failing, or am I wrong, are they likely to fail?

90-120 is the range. 90+ is good.

yeah, i figured it would be about the same as a regular 13b, but what about the low bump?

ok today, I cranked it and I got 3 even bumps. Oil must have loosened it up

if you put a little atf in there, it should clean some stuff up in there. But don't put the ATF in the engine if you will not be running it for a long time. ATF is a detergent and will eat away the plating on the housing.

Yeah, she prolly wont be ready for at least a couple months , thats why I put the oil in rather than ATF.