apex seal reversal...
 

im doing a large bridge on a 6 port to where i have to cut the rotor housings to let the "eyebrow" be fully open to flow. and doing this on stock mazda 3 piece seals. but i am not going to bridge the center iron. just a street port.

ive seen people install the apex seals with the 3rd small corner piece both towards the center iron. in doing this so the bridge dosnt swallow the apex seal piece. but im unsure if theres a special way to do this. i always build my motors from the front rotor up. this would mean the front rotor has the 3rd piece towards the center iror, but the rear towards the rear iron.

im thinking add a little extra vasoline to make it stick as i lower the rotor in realllyyyy carefully... any tips here?

Junk the used (3-piece) seals.
All the new Mazda OEM stuff is all 2-piece now.
I think almost every aftermarket apex seal is either two or one piece.
Superglue the triangle assist piece and put them in however you want.


-Ted

Regardless of what seal you use you need to glue the seals together. A little bit of super glue does the trick. It's how the new seals come from Mazda. As you torque the engine down you will hear snap, snap, snap as they come apart. Makes installation a lot easier and all but eliminates the chance of getting one of the pieces in there incorrectly. I like to lay a piece of aluminum foil over a piece of glass (very flat surface) and glue the seals together on that. Ensures the seals go together flat so there is no issue getting them in their slots and the foil keep the glue off the table.

Opinion:
All BP & PP engines should use 1 piece seals. Preferably carbon or ceramic.
1/2 BP engines can use the 2 piece seals, but the corner piece should be opposite the bridge.
3 piece seals should not be used, at all, in any engine rebuild.

These guys have you covered.

But a tip for glueing them to add to Ludwigs........

I like to take my vernier's and measure the housing, then bump them out one or two thou from that width. Lock them in place there, and use them as a jig to glue the seals together. You can basically dab some crazy glue on, and jam them in....in about 5-10 seconds you remove them and they'll be exactly spaced so the come apart when the engine's torqued.

im building this engine for someone. and he wants to keep the stock seals. so i guess i'll be using super glue and reversing the rear rotor seals to face the intermediate plate. this will keep the little piece away from the bridge...

i always use RA super seals in my motors.

I love that tip.

To add to Ludwigs though, I use me SS workbench - flat as glass - with a piece of that release waxed foil on top, with the waxed side facing up. Glue the assist piece to the seal and fold the foil over. Them with two old apex seals, use one to hold them flat on the table, and the other to make sure the planes on the assist piece and the seal line up. Hold for a minute or so and slowly peel the foil back. It will not have dried all the way by this time so be careful. Trim the excess glue away and leave to air dry. Just before assembly make sure there is no glue residue and if there is, trim with a single edged blade and clean with some acetone.

IMO, Make him upgrade to 2-piece.
3 piece seals in a bridge port engine just doesn't seem safe.

Unless its a shity motor an he wants to destroy it.

I have to agree with N. RotaryTech, I only reuse 3-piece seals on NA engines. My '88 13BT had 80,000 on the clock when I tore it down and the top apex seal had worn significantly on the side (not the face) until it was triangular. I have torn down 150,000 mile NA engines that the 3-piece seals were completely intact and still met tolerances, but not so the turbo (I have only ever rebuilt one turbo engine, so you will have to forgive my lack of experience to draw from there).

My 4-port has new 2-piece seals ($60.00 each from the Mazda dealer) and makes excellent compression (120 psi front and rear). I have not seen many 3-piece seals make that, so I am not sure that they are better. Plus the 2-piece seal is deeper and has more support against side loads (avoiding the triangular wear that I observed on the 13BT).