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Discussion Starter #1
I'm in the process of changing the gears in my '68 elky.

For whatever reason, it came with 2.73 or 2.76 (I forget) - and a REAL healthy engine (supposedly built like a LT-1). Previous owner said it had a "DUNTOV" cam? What the hell's that?

Anyway, the Muncie M-21 was sick (3rd was in bad shape). So I put in a Premier T-400.

I'm now putting in a new gear set. 3.42's with a posi.

In the old unit, why did the carrier bolt breaking taking it out? The guy who is doing it for me said it was real common problem. He's seen that happen lots of times. If that's so, what's the deal?

It doesn't really matter, but I'm very curious.

Just to finish up the rear end, I've also installed the Hotchkis trailing arm set.

>>>Rod<<<
 

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If you are talking about the bolt that holds in the cross pin that has the spider gears on it, yes it is common for the pin end of the bolt to break off.
 

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A nearly full proof way to keep the bolt from breaking is to heat the carrier up where the bolt goes through to melt the loctite. Another cause for this bolt breaking, other than during removal, is that the spider gears wear onto the shaft, which causes the shaft to rotate, or try to rotate, which causes the bolt to break. There is a special drill bit to allow removal of the broken bolt, but it does not always work. Sometimes you can use a pick to spin the remains of the bolt out, but if neither one works, the only way to get the shaft out is to torch it out and replace the carrier. We have an appointment to do this same job Thursday, June 3 on a customer's 69 Chevelle. His bolt not only broke, but the shaft spun in the carrier, and the broken part of the bolt wore a groove in the carrier. The spider gears are literally welded to the shaft due to wear and we will have to torch his to get it out. His bill will be in the neighborhood of $300-350 for labor.

Anyway, we always heat carrier a bit to get the loctite melted, and we have never broken a bolt yet. (We just have to fix the ones that someone else broke)

Hope this answers your question, somewhat.

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70 & 1/2 RS Camaro
SB406 & M20 4spd
70 Malibu
SB350 & TH400
 

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I keep forgeting how young you kids are and that today, as in my time, you don't like to learn history. But it's hard to believe that you kids don't like to learn your Chev history. Zora Arkus-Duntov was the first Corvette chief engineer, and literally, if it were not for him, there probably would NOT be a Corvette today,---------------or anything such as we know it in the way of High Performance within Chevrolet. The man brought High Performance engineering genious to the American auto industry. The Corvette was about to die in the mid 50s and he breathed life into it and it spilled over into the rest of the Chevrolet models. The "Duntov" cam was a long duration, high winding camshaft profile which the man designed. It was first used in very limited numbers in 56 models and then in 1957 became best known, as is common today, by its last 3 part numbers, The 097 (pronounced "Oh ninty seven") . In 1964, his next cam design became known by the lash settings, which where .030 intake and .030 exhaust, thus the "30-30 Duntov Cam", it was also the original 302 Z-28 cam. You young whipper snappers have absolutely no clue how much he affected the entire U.S. auto industry when it comes to high performance. He continually pushed for more output from not only the engines but drivetrain and chasis performance. As Chev increased their reputation for winning, the other manufacturers, primarily Ford, had to keep up. And as they say, the rest is history. The man is your DIRECT ancestor for having the performance macnines that we know today. And before some of you start naming others within Chev who contributed to the image, you are right. Every last one of them worked with Duntov or were directly influenced by him. Not only did he contribute a great deal to designing high performance, but he could drive the dog poop out of any car. People don't use the old "Duntov" cams much any more because there are better cams on the market now. But it still is a good cam profile. It's good to study a little history and learn how and why we got here.

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Discussion Starter #6
DZ -

nah - I know about Zora Duntov - I actually met him in 1988 at Corvette Mike's in Orange, CA.

I have a '68 Vette - L68 Tri-Power, 56k miles. I bought it from the original owner in 1974. I am very tired of it - too much maintenance, a garage queen, etc.

What I meant, what is the Duntov cam? Never heard of such a thing.

But I will thank you for the "youngster" thing.

>>>Rod<<<
 
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