The Caprice has been having difficulty starting lately. Couldn't tell if it was the battery dieing or the timing advanced too far and the high compression was fighting against the starter.
After a bit of testing, I figured out it's the battery on it's way out. It lasted much longer than I thought it would. It was a used battery that I got when I bought the car at the junkyard. I grabbed this one off the shelf full of batteries. Nine years, three months use from a used battery ain't bad, is it?
I met an old time racer at the Long Beach Swap earlier this month. He always seems to have differential stuff there. I gave him my number if he came across what I needed. He called and I came over to his house. His garage would have most of us in tithers. I was. Piles and piles of tunnel rams with carbs and linkage, 9 inch housings, center sections, carbs, posi units, gears and gears, oh my. Looked like his 401K plan on shelves.
This is what I got. The 3.73 gears are Richmond and looked like they were in a car for a couple of days. Still have the yellow set up paint on the teeth. The posi is a factory GM. Not pretty, but it will function when I put new clutches in it.
Time to get that 12 bolt out from under the tarp and get on with it.
I've been doing some thinking. I now have two 12 bolts. The one one the ground with a 3.31 open and the one in the Caprice with a 3.08 open gear, I think. I now have a posi, a Richmond Lockrite, and 3.73 gears. I've been thinking of taking the one with the 3.31 gears and throwing the locker in it and shoving it under the Caprice. Should be real fun when the 454 is rebuilt. Then take the Caprice's 12 bolt and installing the posi and 3.73 gears to put in the Impala. Giving away the open carrier and 3.08's. I don't want the locker in the Impala as I like to autocross it. The Caprice will always handle like shit with a cast iron bbc and AC on it's nose.
Al, the guy I bought this stuff from, wants my 8.2 inch 10 posi and 3.36 gears. He also said he'd buy the 3.31 gears too. I wouldn't have any problem selling the entire 10 diff on Craigslist either.
While working on the car today, I realized I've never figured out what engine I actually for sure.
The block number at the back is: 3956618.
According to Mortec, it could be a '69 302, a '68 or '69 327, or a '69 350. Hmmm, that doesn't help at all. ???
I then went to NastyZ28.com to check out the suffix codes. T0612HB
This breaks down: T = Tonowanda plant
06 = June
12 = 12th day
HB = Uh oh. Two choices: '68 Impala 275 hp 327 with HD clutch, or
'69 350 hp 350 with an Auto in any Chevelle, Camaro, or Nova.
Since 302's, 327's and 350 were all 4 inch bores, 327's were large journal starting in '68. All could be 4 bolt mains. ????????? > > > > > >
I guess it really doesn't matter, but the detective in me hates unanswered questions. Maybe, I should've never looked.
Yesterday, I dug out the 12 bolt I bought over a year ago that had been buried under tires and tarp. Although I did inspect the carrier and gears, I never pulled the axles to see what kind of shape they were in. Even though pulling the pin in an open carrier to get at the C clips is insanely easy; I've never done that before. I've always stayed out of the internals of differentials and trannys until now.
Here's the 12 bolt I bought and ignored the last year.
You can see how good condition the carrier and gears are. There's no wear that I can see on the pinion or ring gear.
The part number is first, but after the 'GM' has 13 and 43. Those are the number of teeth on the pinion and ring gear. That comes out to 3.31. I don't know what the 12 and 64 mean, could be the date of manufacture. Since this diff came out of a 65 Impala SS convert, it could be accurate.
The axles look as good as the rest of the differential parts.
The bearing lands on the axles don't have any wear or pitting. A good sign. These axles are sure beefy compared to the 8.2 10 bolt ones in the car now.
I have a loc-rite in my 12 bolt and I love it..... I'm tempted on the 3.31s... I have 3.73s in mine now, and heaven knows with the torque of the 455 I probably don't need such a low gear..... but then I have to change it....
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