Why Apex Seals Fail

[j9fd3s]

Originally Posted by Barry Bordes

Jonathan, have you thought about heating the plug area while grinding the housing surface?
I believe the factory started grinding either the apex seals or the housing surface that way for better fit while running.
Barry

i'm not sure where this is mentioned, but a new factory apex seal isn't flat, its bowed slightly, so that when its in a working engine and up to temp its flat.

another problem on used housings, this is why they shrink, and why we measure for width, is that the steel liner actually collapses in the compression area, so the center of the housing bows in. its very bad to have leakage between chambers...


mike

[Barry Bordes]

Originally Posted by j9fd3s

i'm not sure where this is mentioned, but a new factory apex seal isn't flat, its bowed slightly, so that when its in a working engine and up to temp its flat.

another problem on used housings, this is why they shrink, and why we measure for width, is that the steel liner actually collapses in the compression area, so the center of the housing bows in. its very bad to have leakage between chambers...
mike

Mike, a slightly different interpretation of the housing wear could be that the high temps in the spark plug area cause expansion between the torqued plates which in turn compresses the surface, distorts the face, and chafes the faying surfaces (which causes the undersize housing measurements).

Notice the temps where we want to provide extra cooling are doubled that of atmospheric boiling water.
Barry

[j9fd3s]

that very well could be. next time you have some used housings handy, take a straight edge and lay it across the surface, its above the spark plugs that seems to do the worst.

i did build a couple of motors with a stock diameter stud kit, and i was told to tighten it to 50lbs, but i think this is actually bad. it also certainly didn't solve the actual problem which was stock ecu/injectors with a street port and big turbo! or more correctly the owner.

after thinking about it, i think the small diameter studs actually hurt more than they help. the studs DO NOT locate any of the housings any better than the stock bolts, plus #50lbs of torque the rotor housings probably ARE bowing, which is bad!

mike