Donnybrooke Green '70 #s LT-1 Corvette Convertible

[TimG]

An LT1 could be had with no radio, so that wasn't the change. It was the bell housing and 10.5 inch clutch, Lynn. It used the L88 starter that was dated 1968 and was in left over inventory.

[Lynn]

So now that this thread is already slightly of the rails, how about another rabbit hole?

Always wondered why some vehicles got the 10.5 clutch and others the 11. Wasn't based on power, as ZL1s got the 10.5 as well as the Z/28.

In theory, the 10.5 would be easier to shift at high RPM. Maybe based on expected rear gear?

[TimG]

That is a good question, I never understood that, either.

[69M22Z]

You can definitely tell the difference as far as the ZR1 engine revving faster with the smaller flywheel. ZR1's are really neat.

[napa68]

Originally Posted by 69M22Z

You can definitely tell the difference as far as the ZR1 engine revving faster with the smaller flywheel. ZR1's are really neat.

That small flywheel was also in the 65 L78 Corvette's. Which ultimately proved to be the demise of many a 65 L78

[olredalert]

----Lynn,,,It's all about the weight of the flywheel. Less weight faster ability to gain RPM. At Classic Motors (circa 1977-78) I had a 67 435 convert that had been drag raced prior to my ownership. It had the factory flywheel set-up. we had to yank the motor for some work and along with that I decided to install the L-88 flywheel, bellhousing, and clutch assembly (10 1/2). That 435 became probably the fastest one I have ever had with a basicly stock engine. The car was carrying a 456 gear set which would also help a bunch, but lower more normal gears would also benefit....Bill S

[luzl78]

That’s why racers like to put aluminum flywheels on their motors.

[TimG]

My Scarab had a light weight flywheel and it would rev to 8,000 RPM before you knew it.

[markjohnson]

So, it sounds like the 10.5 clutch is the reason for a different engine suffix than a regular LT1. That actually makes all the sense in the world since bellhousings have orange overspray after being painted on the engine at Tonawanda. Clutch & PP plates were obviously installed at Tonawanda before the bellhousing and not at the final assembly plants.