Question : 3.1 c-shaft in a 2.8 blk..c-shaft flywheel flange

[rd400@sbcglobal.net]

Hi folks, new to the forum but after looking around this is gonna be great. Here's the problem: building this to repair the g-friends Blazer but i've noticed the crankshaft rear flange {flywheel mounting flange} has multiple diameters on it. Moving from the #4 main bearing towards the flywheel there's a smaller dia. then the dia. increases for about a tenth of an inch{lenght} then the dia increases again to the rest of the crank flange.These's probably not .06 difference in the dia. of these steps but i've read where there are steel sleeves available to save this flange/crank...My question is the seal {10MM} has two different dia. on it so i'm guessing the 1st step is supposed to be there{the one closest to the #4 main} but it appears as tho' there's been some wear further back on this flange..SO, the repair sleeves cover how much of this flange? All of it or just the part that works w/the dust seal? Sorry to be so wordy but this is the first 60 deg. i've built and i wanna do it rt......................Randy

[bszopi]

Welcome to the site!

Can you give us a little more info on the motors you are dealing with, mainly the years? There are some slight differences in the various years of the 2.8 blocks, so knowing which one we are talking about will help out. Thanks!

[rd400@sbcglobal.net]

Ok, i think i have this 'puter figgered out, and i think i've figgered out the crank flange seal thing...but i'll relate what i've found..1ST: it's a 2.8/internal balence Blazer-S10 PU motor w/a ARI crank kit..Ok, this block previously used a 10MM seal {at least the new one that came w/the kit seems to fit} but the flange dia. has been damaged by the previous motors rear seal.The area where the dust lip would rest is clean-no damage, but the area where the oil control lip would rest is damaged and appears to have been repaired {badly}....So my question now is: how long are the repair sleeves that correct this oil seal damage?and BTW, has anyone used one of these sleeves and did u have problems.............................Thanks, Randy

[geoffinbc]

Well all I know is federal mogul makes the sleeves. They work fine but I am pretty sure they need to be installed by a machine shop. It may be cheaper to get a new crank. Any 3.1L/3.4L/3100/3400 crank will replace the one you have. I can get a crank here for $25 you should be able to find similar. If you were to grab a late model 3400 crank I am willing to bet it will go in without machining on standard bearings.

[rd400@sbcglobal.net]

Actually i own a machine shop, in fact i had the crank on the lathe yesterday {just to hold it while i measured the mains/rod journals}..i was just looking for a history on the sleeve and its lenght. On another subject, has anyone run rod/main clearences different that the factory specs..BTW, i have the factory manuals and the "How to rebuild your GM 60 degree engine" by motorbooks international....What references are you folks using.
Later, Randy

[geoffinbc]

Yea I have that book.

If you buy the sleeve you will have material to play with so you can machine it back to spec when finished. Keep the stock bearing clearances they work well and are the same as any other motor with similar size journals.