I could have SWORN that I saw a spec for this somewhere!

I have a mass of 12A rotors. I tore down five core engines in the past month or two. Of the ones that weren't massively rusted and NFG, the others all had significant apex seal slot clearance.

Okay, there's that, but the interesting thing is I am measuring the apex seals at 2.8-2.9mm thick, not 3mm thick. Some of the apex slots I have measure exactly 3.0mm and others are larger.

I know that most/all of these engines were run without air filters judging by the state of the side housings and side seals (why do people do this??) and I also know from experience that dirty air also wears apex seals thinner.

However I don't have any "New" 3mm seals to measure clearances with, and I sure as heck aren't going to order a set, or even just ONE, to measure with.

Can anyone help a rotorhead out and measure the exact thickness of a new 3mm apex seal, or some hard and fast dimensions for the apex slots?

 

Nobody has measurements of good slots or new 3mm apex seals?

 

From the mazda factory manual
Apex seal width 3.0mm
Clearance of apex seal and rotor groove 0.05-0.09 mm Limit .15mm

 

That's what the manual says. The seal slots that I have measure anywhere from .115 to .118" which is 2.92 to 2.99 mm. Clearly if the apex seals are supposed to be exactly 3mm then they will be an interference fit even in my worn out rotors.

Thus, why I am interested in what a new seal actually measures, not what a seal nominally measures according to what the people who wrote the book were told by the engineers.

 

This from a brand-spanking-new pack of Atkins 3mm seals I bought at Sevenstock from the man himself. Measured by me with a known accurate vernier micrometer:

0.1157" nom, +/- 0.0001max (observed)

Translation: 2.93878mm +/- 0.00254mm

So I hope this helps.

 

THANK YOU!!! That's awesome, just the info I need to work with.

 

this is the reason i didn't just look in the book.

the FC FSM gives a spec for a new apex seal at like 8.5mm or something, and a new seal is actually like 10mm. since the Mazda seals have changed part numbers a few times since my 1988 shop manual was printed, i was thinking they made a running change at some point. we actually know they have, 3 piece to 2 piece.

with width they can't make as big a change, because they have to have the seal still fit an unchanged rotor, but still