rear main questions

[punisher7]

I am going through my truck and taking note of what needs to be taken care of come snowfall here in Wisconsin. I have a minor leak from the rear main, and a little bit of seepage around the oil pan. The truck has a 327 backed by a turbo 350. I am told it is a mid 60's 327, bot dont know much else. I know with my last ford motor I had to get at the crank and determine which crank I had for the rear main. Am I in the same boat with the SBC? This is my first attempt at doing anything to a chevy motor. I always swore I wouldn't drive anything with a chevy motor until I built a Ford. So much easier to find everything for these SBC motors.
Thanks

 

[Gastrick]

I think all of the rear main seals are pretty much the same for the sbc 1959-1985. After that, they went to a one piece rear main seal. You can change it by just dropping the pan and the rear main cap. You have to slide the upper part of the seal around the crank if you do it that way.

 

[punisher7]

Ok sounds good. I will go pick one up and give it a shot. the two piece ones are pretty easy to get on with the crank still in. thanks

 

[zzrodder]

You will need to find out what year it is, there are different size crank journals.
55 - 67 small blocks have smaller crank journals than the 68 - and up ones. 68 - 69 327's are much less common and will accept the 350 crank with no mods.
You can visually identify a small journal 327 easily, they have the crankcase vent tube at the rear of the block beside the distributor and the oil filler tube is in the front of the intake manifold beside the thermostat.

 

[punisher7]

Ok sounds good. I will take a look in when I roll out of bed. Thanks ZZRODDER

 

[WickedFast1]

And if the block has been line bored takes a diff seal

 

[punisher7]

How do I tell if the block has been line bored? Hell what does that even mean?

 

[zzrodder]

Line boring an engine involves shaving a few thou off the mating surfaces of the main bearing caps, bolting them back on, then boring out the main bearing saddles to original spec.
I've never heard of the need to use a different rear main seal when a block has been line bored, think it's unlikely to affect the way it seats.
I'd be surprised to find that machining operation was performed on your 327 unless it was treated to a major expensive rebuild at one time. Usually line boring is only done if the engine has had spun main bearings or the crank or main caps have been changed - or someone was going the full blueprinting route.

 

[punisher7]

OK sounds good. my motor is built up, but I don't think it was done up that much.

 

[RPM]

There is a large journal crank and a small journal crank. But good news is the take the same rear seal. If it was align bored, it still takes the same rear seal. So you are good. Be sure when you change the seal to put a small amount of sealer in the corner edges of the rear cap. Oil cam actually leak past the cap even if the seal is good.

 

[WickedFast1]

sorry guys, I built the 400 block not the 350 but did have to go with a fel-pro 2909 seal for line honed block. but would like to know how his motor turned out?