BB rear main seal

[Four-Forty-fied]

Anyone have the torque spec handy for that aluminum cap that half the rear main seal sits in?

Also, any tips to prevent me from having oil leaks? i.e. what type of sealant do ya recommend smearing around that cap and on those little rectangular gaskets? I was just going to use Felpro copper RTV.

How do you keep oil from seeping past where the two halves of the split seal meet? RTV or just the pressure from the torque of the cap bolts.

I've only built motorcycle engines, so this is my first V8 rebuild. Which reminds me, what exactly holds the camshaft in place? Seems like it could just slip back and forth if the chain loosens a little.

[Chryco Psycho]

I use Ultra Black or Copper silicone , the Ultra is high oil resistance
the seal is made slightly long so it will put pressure on the seal ends where they butt together , but a small amount of silicone can be used there as welll
 the cam is held in place but the dist drive & the cam timing gear , the dist drive loads the cam rearward in the block & the gear rides against the front face of the block

[matt63]

I usually stagger the seal ends so they are not on the split line.  I have also heard that milling 0.010" off of the rear seal cap mating face helps although I don't have first hand experience with this.  I think CP knows more about this.

[Four-Forty-fied]

Thanks CP, my copper (RTV or silicone? Not sure now.) actually dried up so I'll have to get my hands on some ultra black. Makes sense about the cam. Didn't get that far yet.

Matt, thanks but I don't think I'm going to mill the cap unless I have a problem. I was just curious how these split seals hold up.


I found the torque spec: 30 ft-lbs.

[matt63]

I found that the BB tends to have leakage problems so take extra care.  I remember one glorious day spent underneath my Demon removing the oil pan and windage tray to change the seal out. 

[rumblefish72]

Fourty-Four-fied,

Did you consider the Indy aluminum seal holder?  I hate leaks and my last motor had a little seapage not at the crank seal but where the cap mates to the block (long square cross section seals).  I thought I had good coverage with ultraseal gray silicone smoothed into this seam from the flywheel side but when I took the bellhousing off a yeart later to put a new clutch in, there was a little oil in there.  This time around, I went to the Indy seal cap.  It uses a double length of O-ring to seal between the cap and the block on each side.  The top of the O-ring sticks out in a loop and you trim it flush with a sharp razor.  This seems like a better sealing system to me.

I attached the best dpic I could find.  I remember having to trim the studs on the #5 main cap so they would fit under the lip on the Indy seal cap.  I haven't run the motor yet so I can't tell you if I have a leak but I'm hopeful that this is the way to go.  The Indy stuff is usually well engineered.

just my $0.02 ...

-Rumblefish72