Rubber plugs in corner seals
 

Just curious why those rubber plugs are in the corner seals.....
Why design them that way?? I don't really see a point.
What would happen if you didn't use them at all?? I've never seen rubber inside an engine before! LOL.

didnt they change them on the 3rd gens. and mine wernt rubber anymore when i took my engine apart

I beleive you can get onepeice, solid seals from Atkins...
but my question remains, what would happen if they weren't there?? When I dissasembled my engine there were several missing, but compression was fine with the exeption of the blown side seal.

i know they hold half of the apex seal or whatever that part is called but why they made them 2 peices i have no idea.

The dont hurt anything, aid in compression and, are reallllllllll cheap. jsut put new ones back in.

Yeah i'm pretty sure they're just there to aid in hot start cranking compression...

There was a good thread on here about it, or maybe over at nopistons.com or something.. i can't remember.

I'd like to find out... hmmm.

My opinion/theory on the matter is that they are there to *try* and prevent carbon buildup UNDER the apex seal, where the springs sit. At this, they fail miserably. The rubber turns rock solid in 20k miles, and often times they break up and fly out the exhaust.

I have built a lot of motors without them, and noticed NO difference in hot start, cold start, or compression, idle, boost, anything. Not even carbon buildup on teardown.

Great. Exactly whta I was looking for!
Thanks!

I was looking into ditching them and putting some FD corner seals in, you think this would be any better than using the olde tyme ones again?

the seals are the same. the springs are somewhat better.

I think the spiral leaf spring 3rd gen corner seal springs are quite a bit better than the earlier wire sping design.

My low comp rotor Pineapple 3mm seal rebuild did not use the rubber corner seal inserts and it has always been VERY easy starting hot or cold- started RIGHT up when I installed it as well.

I agree that the FD and later corner seal springs are much better in *design*. However, I find myself asking, once installed in a running engine, how much better they are in practice? The seal itself is the same, so it is no stronger. Once the seals and springs on teh side of the rotor get compressed when tightening down the stack (tension bolts) they never move again, in contrast to apex seals which are constantly moving.

Whast I'm saying is that, in my estimation, 2 equally built engines, one with s5 and earlier CS springs and one with 93 and later CS springs, would both perform the same under all conditions.

However, I have no actual data to back this up.

I agree with you, however, I have seen a few cases where one of the S4 springs broke in half. Don't know the cause, I assume abuse or lack of maintenance. In one of the motors, a piece of spring wedged between the small end of the apex seal and the corner seal slicing a real nice groove in the rotor housing. I looked like it acted as if it was a brake lathe. I prefer the S5's only for that reason.