When I first bought the Firebird, I replaced the seal with the engine in the car by lifting it slightly off the mounts and dropping the pan. I managed to remove all the caps and lower the crank just a bit to use the rope seal tool to pull out the old seal and install the 'TIN INDIAN" seal. Didn't last long so I pulled the engine out. That resulted in a rebuild. The mains were bored at least three times. I put in the 'graphtite' seal. That lasted about 1000 miles. I pulled it again and found the crank was brown around the seal area from heat. I measured the rear seal grove, it was WAY out of round. About 16-20 thou out at the cap and the block.
I tried a dozen machine shops trying to get someone to re-machine the groove. No luck! A one piece chebby? yes, a Pontiac no. I thought a machine shop would want to do something besides bore out SBCs all day long. I contacted a shop in Tenn that would do it but it was $800 for shipping.
I bought some 1-1/4" round ground steel and some !" plate aluminium. I made two doughnuts to fit into the bearing bores and some clamps to hold the shaft in the correct position. A hole drilled through the end of the shaft to hold a cutting tool such as those in a lathe. I got the cutting bit from KMS tools. I shaped the cutting edge the same profile as the seal groove. A threaded hole drilled 90 degrees to the first one was used to hold the cutting edge in place with a lock bolt.
After positioning the tool in the block I moved the cutting edge out so it just touched the groove and gave it a few turns, then loosened the lock bolt and moved it out a couple thou. I measured the groove after every adjustment and eventually took 18 thou off the cap and 12 off the block.
I assembled the engine with the BOP two piece chevron seal, after around 6-7000 miles it still didn't leak.
A lot of machine shops have hundreds of thousands of $$$ in machinery, I've got a drill press a bench vise and a press. Machinist used to love a challenge and a change in routine. I guess they are a dying breed. Too bad.
That's awsome!! You must be a machineist or were one to come up with that idea. My 67 bird has a 75 400. I will attempt a rear seal job asap for iit's leaking like a siv. Probably go with a two piece seal, I believe that's what those engines had. I'd like to do the job with the eng in the car. I hope there aren't any issues like you had.
Many Thanx 67 Firebird 400 conv 69 LeMans 400 auto od
