PeteVS

I'm putting together a spare distributor for my 250 HP '63 to carry in the event that my "Stealth" electronic unit dies. I'd like to be able to set it all up so that it could be a simple on the road swap, positioning it the same as the "regular" distributor. Problem is, when I install the drive gear, there are two ways to install it. The gear has 13 teeth. The cross hole for the pin lines up with one of those teeth on one side of the gear and between two teeth on the other side. That means that if the gear is installed one way or the other, there will be a half tooth difference in shaft position. Is there a "factory" way to get this straight? I notice that there's a dimple on the gear's hub. Is this intended to be oriented one way or another with the "square" or "round" rotor holes in the plate on the top of the cam assembly? I seem to remember messing around with this a bunch of years ago when I redid the distributor that's in the car now but the exact outcome of my efforts lies buried in the engine.

I scanned through the shop manual and this thread but found no mention.
https://www.corvetteforum.com/forums...-position.html

Thanks for any help here!

Powershift

For factory engines and factory cams, the dimple on the gear points to the rotor tip.

Not all cams are ground this way. You need to check what you already have in the car and then align the spare to be identical.

Larry

tbarb

You have a very good question and hopefully I can offer some help. From the factory the dimple you mention will align with the rotor tip when the gear is installed correctly.

The problem arises if someone changed the camshaft to a aftermarket (non GM) part because the manufacturing process is different and the rear drive gear on the cam is not indexed the same. This will require you to rotate the distributor lower gear 180* then install so the vacuum advance will sit in between the intake manifold runner and the coil bracket.

Pull the current distributor up and see how the gear is installed and copy that if the vacuum advance looks to be centered. If you have a breakerless SE ignition, my experience with that is it may hit the coil bracket when setting the initial timing at 6-8* BTDC and may require turning the gear 180*. The rotor phasing may be a bit off with the Breakerless SE and it fires the spark earlier than the points.

PeteVS

Super big thanks to Larry and tbarb!!

These are pix of the '63 at TDC when I got everything set up the way it should be. Now my only concern is, "Is the cam the rebuilder put in the engine a "factory" cam?" He wanted to put in a slightly hotter cam but I wanted as much factory stock as possible.

PeteVS

PS: I helped put a stock cam in a '57 ages ago. I remember that when the cam dot lined up with the crank dot, number one cylinder was at TDC. So, we put the distributor back in lined up to fire number one. Wouldn't run. Seems it was TDC EXHAUST. Is this right??

MelWff

No you where at TDC for cylinder number 6

Powershift

But this is really saying the same thing as the OP in the previous post.

Larry

For the OP: I would pull your existing distributor and see where the gear dimple points. THEN, I would make the spare distributor the same way and install it and time it correctly. Then mark the distributor and manifold with a punch mark(s) or with a paint marking pen. Then remove it and store it away.

The reinstall the current distributor and set the ignition timing to your spec.

Larry

RoudyRick

When was the last time you had a distributer failure on the road? Your tool caddy must be full or spare parts for the road. Can't ever be tooo carful, be prepared

PeteVS

Back in the day, I was on a 5 hour trip home when the car misfired a couple of times and came to a stop on the side of the road. No spark. I lifted the cap and saw that the condenser lead had gotten tangled up with the mechanical advance. The lead didn't go under the coil lead and was then able to work its way up. Then, when I redid everything a few years ago, I did the distributor first. A year or so later when the rebuilt engine was being fired for the first time, it wouldn't start. The points had oxidized a bit. Got the engine running and then everything sat for a year or so. Finally got back to it and it wouldn't start again. Same issue with the points. So, I replaced them with an electronic unit. Now, it runs fine but I'm somewhat afraid of the electronic unit dying. So, I want to carry a spare distributor and a 9/16" wrench.

Frankie the Fink

I have a '63 250hp with the distributor rebuilt by Lars and the Breakerless SE; there is NO problem putting the distributor in and adjusting timing with the distributor gear in stock position.

If you're going to change a distributor roadside then carry some blue painter's tape with you. Mark where the tip of the vacuum advance points on the valve cover then use the blue tape to mark where the rotor points on the engine (intake or wherever). Do NOT bump the engine over.

On installing the new distributor point those two items at the tape where you marked them respectfully. This will get you home with close to original timing which you can check when you get a chance..

Roger Walling

I have a friend that just went through two new distributors and one oil pump on a Ford because the manufacturer used a split pin in the gear instead of a roll pin and it came out in pieces.

RoudyRick

Ford!!???

Jackfit

I found it was easier to just carry and extra module. That is the only thing that will break . Takes up a lot less space and ease of installation.

Jack