Odd Flywheel Question

[nonstop]

Hi everybody!

I hope someone can help me out! I am trying to calibrate my tachometer out of a c70. It has a pick up off the ring gear. There are a few options for flywheels, and I was wondering if anyone would be able to tell me the tooth count of the flywheel for a VT-225. I found the count for the 3208 and the 8.2, but I could not find a definitive answer for the VT-225.

Any help is appreciated!

Thank you,

Nick

[Airdirect]

Wow, you have a C70 with a VT-225? I bought one of those new. Only a few of them were built, GM had to shut down the line for more than 30 minutes to get the engine stuffed in the truck. I was told that is the reason it was discontinued so quickly. Love to see a picture of yours, here are the only pictures I can find of ours. My current C70 is a 1979 with a Detroit Diesel 4-53T. I converted it to a rollback and use it to haul my tractor collection to shows. Here is a link to my build.

http://67-72chevytrucks.com/vboard/s...d.php?t=721374

[Bob B.]

Originally Posted by Airdirect

Wow, you have a C70 with a VT-225? I bought one of those new. Only a few of them were built, GM had to shut down the line for more than 30 minutes to get the engine stuffed in the truck. I was told that is the reason it was discontinued so quickly. Love to see a picture of yours, here are the only pictures I can find of ours. My current C70 is a 1979 with a Detroit Diesel 4-53T. I converted it to a rollback and use it to haul my tractor collection to shows. Here is a link to my build.

http://67-72chevytrucks.com/vboard/s...d.php?t=721374

So that was the reason! The VT-225 was announced for the 1980 model year C-70/C-7000, was not available until after March, and didn't come back for 1981. I never saw one, and thought none were actually built. My company had a number of 1988-89 C-7000 TopKicks with Cat 3208's in them, and that was a tight fit. Had to jack the cab up a bit to get the valve covers off. The other rare engines in 80's Chevy/GMC medium duty trucks were the Deutz air-cooled diesel (saw one of those, they exist), and the 5.9L Deere diesel. Quite a story behind the Deere, to bad it didn't work out.

[Airdirect]

The VT-225 was a sorry engine, ours failed after 50K, Cummins warrantied it and it failed again at 100K. I think the turbo was just too much for the engine design. I choose the VT-225 because it was a Cummins, had replaceable liners, and was the largest horsepower offering. The engine did not have a lot of torque, you had to keep it wound up to maintain boost.

[Bob B.]

Originally Posted by Airdirect

The VT-225 was a sorry engine, ours failed after 50K, Cummins warrantied it and it failed again at 100K. I think the turbo was just too much for the engine design. I choose the VT-225 because it was a Cummins, had replaceable liners, and was the largest horsepower offering. The engine did not have a lot of torque, you had to keep it wound up to maintain boost.

That was pretty much typical of all the Cummins V-8's, even the 903 needed to spin to make any power. The VT was a newer version of the old 'Triple Nickel' 555 with a turbo. The 555's were used around here transit buses, but not many trucks. They did have a nice sound to them though.

I liked our old TopKIcks with the 3208. We had little trouble with them and they turned sharp and rode well.

[nonstop]

I only wish I had anything that size! Especially with the VT 225. Unfortunately space is a huge limiting factor! I got the gauge cluster from a truck with the VT 225, and am adapting it to my K2500.

I have been following your build, and I love that truck!

[Airdirect]

You had me excited, I doubt many if any of the VT-225 powered survived. The truck you harvested the cluster from, was it in the junk yard?

[nonstop]

Yeah, it was in a yard that closed down years ago. Used to love going there - it really got my mind going!

[MJN]

Originally Posted by nonstop

Hi everybody!

I hope someone can help me out! I am trying to calibrate my tachometer out of a c70. It has a pick up off the ring gear. There are a few options for flywheels, and I was wondering if anyone would be able to tell me the tooth count of the flywheel for a VT-225. I found the count for the 3208 and the 8.2, but I could not find a definitive answer for the VT-225.

Any help is appreciated!

Thank you,

Nick

You could reach out to the Tach man, www.tachman.com he restores/calibrates GM truck tachs and may have a solution for you. If you can post a picture that would help here too and details about the k2500 you're installing it in. I've only had one diesel tach out of a medium duty truck with a 8.2 and sold it to a friend with a pickup that had a 6.2.