I've overhauled my firts 20B. I assumed that all the dowel pins were the same, as the 13B's are. I've been told now that two of them were different. I have no idea where I installed the dowel pins. everything seemed to fit normally and bolted up fine. Can anyone help me with my delima on whether or not to disassemble my motor? And where and why are there two diffent dowel pins?

 

There are 2 different dowel pins. These two pins have a 1" taper and are located in the front rotor housing. The taper is suppose to face the thick center plate. Mazda did it for a reason so if I were you, I would disassemble the engine and make sure they are in the correct place.

 

I'd wait for a second opinion. Why? Because it's a used engine, you went to all that trouble to put it together, the difference in thickness is very slight and I think Mazda did it so the front would have just a little bit of fudge room.

Again, since it's a used engine, the parts aren't going to be as uber-tight as when they were new, so if you don't have the time to tear back into it, I don't think there would be any harm done.

 

I wouldn't take any chances, tearing down and rebuilding a good motor is alot better then tearing down and rebuilding a blown motor.

Why risk it?

 

That little bit of fudge room may be enough for him to prematurely twist the block if they aren't installed properly.

 

umm, there is no block to twist?

Unless this is some kind of strange super-special 20b that I've never seen before.

If the engine rotates by hand freely and makes compression, I'd think its fine. Endplay normal?
The difference in any motor with more than a few thousand miles on it is probably so insignificant at this point anyways as is mentioned above.