VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc REAR END TRANNY AND ENGINE NUMBERS

i just puchased a 57 chevy pick up from california, I know this is a little out of the usual, being this club is geared to original cars. good running truck , not the original engine or rear end, possibly the original tranny First off i have a problem with the drive shaft rubbing against the crossmember of the frame, Ive been told the pinion angle could be off. Ive been also told i should set it to the angle for the rear end, not a 57 chevy truck. So first question ,The rear end is a 10 bolt,with a stamped groove in the pumpkin. numbers are 3894859NF, anybody know what that is off of and or the pinion angle for it? Next question, It is a v-8, thinking a mid 70s-early 80s, Got some numbers off the block, by the firewall, Passenger side, GM3970010, Anybody able to tell me what it is.Also, any help on how to set the pinion angle would be appreciated. Im also guessing that a easy fix would be to add a leaf to each of the rear springs, But id hate to make it ride rougher,not a cushy ride now. thanks guys, Bill Pearson

The 3970010 engine could be for several years. Also replacement blocks for everything to a 1969 Camaro Z28 302 to a 350 CI truck used this engine and it was both a 2 and 4 bolt main.
My best educated guess is that it could have been the factory block from something between 1975 and 1980.
Probably is a 350 as that is what most of the engines were that the block casting number was used for.
They used the block for all the different engines and just bored it out to the necessary size.
I don't have anything on the diff. but if a 10 bolt probably was from a car with a smaller engine (bigger engines had 12 bolt). Year wise I would guess around late '70's.
The 1955-57 cars and 1955-59 trucks has a transmission case casting nummber of 3845122.

The pinion angle is dependant on the engine angle. Get one of those magnetic dial protractors (around $5.00 at Harbor Freight, Sears, etc) and when the truck is on a level surface on all four tires, place the level on the carburetor mount surface of the intake manifold. If the engine was installed correctly, the protractor should read 0°.

Next place the protractor on the flat end of the transmission by the U-joint. The angle will probably be around 3°.

Here's a link to one article or you can Google "Pinion Angle" and find dozens of other sites, as well:

http://www.iedls.com/ptsetup.html

Lastly, place the protractor on a surface of the rear end, preferably the flat near the rear U-joint and that reading should be parallel or within a degree or two of the transmission reading. This is the correct way to set it up for the street. For drag racing it's a little different.

thanks, i will take a peek this weekend