340 Rear Main Seal ?

[DustyEd]

Just wondering what you "race guys" are using for the rear main seal.....Viton or Rope style?

 

[flyfish]

I just have your basic Felpro rubber seal in mine.

 

[brian6pac]

you can run a rubber seal but you need to polish the grooves out of the crank first or it will not seal.

 

[DustyEd]

I just have your basic Felpro rubber seal in mine.

And I assume your crank had the knurling on the seal contact surface, right?

 

[DustyEd]

you can run a rubber seal but you need to polish the grooves out of the crank first or it will not seal.

Wow, glad I asked and thanks for that info. You are the first to mention that point. I'm replacing the seal with crank in block, so that means no polishing and I need a rope, right?

 

[brian6pac]

Wow, glad I asked and thanks for that info. You are the first to mention that point. I'm replacing the seal with crank in block, so that means no polishing and I need a rope, right?

Most of the times thoughs grooves are ruff and will tear up a rubber seal, look at them real close and see if you can feel them with your finger, if they are smooth enough you might get away with it but if they are ruff NOT.

 

[flyfish]

And I assume your crank had the knurling on the seal contact surface, right?

Yup...I'm assuming that is there to push the oil away from the seal (just a guess). I have not had an issue with this seal, however; I had my first ever rear main seal leak with this same gasket when I first built this engine....not sure how that happened, but after pulling the motor and changing out the seal it has been fine. This is motor # 7 for this car (I think), so not too bad to only have 1 leaker.

 

[413]

I use the rubber seals with a knurled crank on 440’s with no leaks.

 

[DustyEd]

Most of the times thoughs grooves are ruff and will tear up a rubber seal, look at them real close and see if you can feel them with your finger, if they are smooth enough you might get away with it but if they are ruff NOT.

I can barely detect the groves with my finger, but are very noticeable with my finger nail.

 

[Bewy]

On a 440, I used the one piece seal. I had the crank knurling ground off; engine has not been run yet.

 

[brian6pac]

I can barely detect the groves with my finger, but are very noticeable with my finger nail.

Most rope seals leaked a little, so it might not leak with a rubber seal but it might. DO you feel lucky.