Technical origins of "long tip" and "short tip" distributor rotors?

[Jerry G.]

Re: Technical origins of "long tip" and "short tip" distributor rotors?

FI distributors can't move they are pinned. Better design

[Terry M.]

Re: Technical origins of "long tip" and "short tip" distributor rotors?

Hey Joe,

Enjoy the road tour and the convention. Would be interested in seeing a pic of your fixture.

I will have to think about this some. May be a good winter project. -Dan-

Dan,
Sorry to take so long, but I just came across this photo. Not mine, but if we wait for me to get a photo of this set up in my cluttered garage we will all have more gray hair (or none as applicable):

Sun dist and witres.jpg

[Richard M.]

Re: Technical origins of "long tip" and "short tip" distributor rotors?

So with a factory TI should we run a wider SP gap?

[William C.]

Re: Technical origins of "long tip" and "short tip" distributor rotors?

That is what drove GM to the HEI system eventually...

[William C.]

Re: Technical origins of "long tip" and "short tip" distributor rotors?

That's a maybe, as the factory TI was not designed for higher voltage as the HEI was. The most basic purpose of the early factory TI was to eliminate points changing, and the TI coil was a different turns ratio to match the output of the TI box. Actual voltage was about the same as a points system. Power output of the system waited for the HEI system that was a complete system upgrade, as GM was looking ahead to coming emissions regulations with great concern (heavy handed government and big fines) so the entire system was upgraded. TI was essentially an option for folks that didn't want to change points performance wise.

[Joe R.]

Re: Technical origins of "long tip" and "short tip" distributor rotors?

Hi Terry:

Attached is a photo of the machine I have been working on that I think Dan was asking about. It does the same thing as a Sun machine but costs only about $100 to build, assuming that you already own a dial-back timing light and a Mity-Vac vacuum pump like those in the photo. Through the wonders of ebay, the drive system components are a heater fan motor for about $10 and a PWM motor speed controller for about $8. Power comes from a car battery (the orange cable on the left).

For this machine, the coil, distributor cap, and ignition wires are part of the fixture. This allows the use of a conventional timing light to replace the strobe in the Sun machine.

I'm in the process of writing a Restorer article that provides details on how to build one of these.

[Terry M.]

Re: Technical origins of "long tip" and "short tip" distributor rotors?

NO, at least I would not. The factory TI does nothing to make a hotter spark. It only eliminates the nuisance of adjusting and changing points and it eliminated the issue of point bounce or float at high rpms. I believe if you look at the tune-up specifications in your FSM (Factory Service Manual) you will find no different spark plug gap for TI or non-TI Corvettes.