Locked out distributor advance question
 

I recently locked out the advance in my distributor. I took the car out for testing with my backup engine last night and while the engine has some issues, the distributor worked out fine, and I had no trouble cranking when hot. But the timing did wander back and forth a couple of degrees, and when I put it in I could feel the rotor moving back and forth just a little.

I'm pulling the distributor out anyway to swap back to my good engine now and I'm thinking of putting a little tack weld between the plates to prevent any movement at all. There's no electronics in this, just the magnetic pickup. I don't think that would be bothered by one second of arc.

What do you guys think, good idea, bad idea? Any drawbacks other than the obvious increased difficulty in restoring centrifugal advance later on?

Re: Locked out distributor advance question
 

Dave,

another option is to drill through both the fixed and movable plate and install a roll pin. Doing so gives the option to go both ways.

Re: Locked out distributor advance question
 

That's a good suggestion by Larry. If you decide to put a small shot of weld on instead, take out the pick up and cover the sensitive areas with tin shield or pull out the shaft. Always place your ground cable as close to the weld area as possible and put the weld where it could easily be removed with a thin grinder wheel.

Re: Locked out distributor advance question
 

the timing wander could also be caused by the timing chain and or the gear lash on the cam/distributor

Re: Locked out distributor advance question
 

Before I installed it I held the gear in one hand and the rotor in the other. I could feel a little back and forth movement in it.

Re: Locked out distributor advance question
 

Two things come to mind . First , if you tack weld the plates ,t will be very hard to index the distributor cap . It would be better to drill a hole through both plates then file a slot in one , so you can move the reluctor around to get the timing and the cap index correct . Second is to shim the shaft to get minimum endplay on the gear .

Re: Locked out distributor advance question
 

MSD distributor?

Re: Locked out distributor advance question
 

No, It's a Summit brand, whoever they got it from.

Re: Locked out distributor advance question
 

I'll know more tomorrow morning when the distributor comes out, but my plan at the moment is to remove the gear, pull up enough to be able to slip in one or more flat washers as needed to take up the gap, then reassemble. With the right thickness of washers it should hold the plates together firmly when I tighten down on the nut.

Totally reversible too.

Re: Locked out distributor advance question
 

The MSD units are known for not having enough threaded section on the little pin that locks the plates together. A flat or locking washer behind the nut takes care of it.

Something to check, anyway. -Al

Re: Locked out distributor advance question
 

I'd just set the timing at 3000 rpm as you get a few degrees of timing difference from idle to 3000 from distributor, cam/distributor gear clearances and cam end play.

Re: Locked out distributor advance question
 

It's done, one small lock washer, probably for a #10 screw, fit perfectly. Did not noticeably increase the space between the two surfaces but was just enough to be able to tighten down firmly. No more movement at all.

Re: Locked out distributor advance question
 

Between all of the allowable tolerances of the cam and dist. gear and the rubber band up front, (timing chain) you'll never remove all of the slop. But don't worry about it. When it's floored its tightened up.

Re: Locked out distributor advance question
 

Agreed, when I said no more movement I meant in the centrifugal advance mechanism itself. There was no noticeable change in the gear clearance, and I didn't add to the shims.

Re: Locked out distributor advance question
 

Back in the 70's, GM sold a pack of distributor shims. They were .010 or .015 maybe ?
Ten to a pack , and it would take about half of them to shim up a distributor gear to remove most of the play there.
Always wondered why they left them that loose . GM must have seen as a hi-po issue, or they wouldn't have sold them.
I wonder if they are still available or somebody has them as NOS ?

Re: Locked out distributor advance question
 

I always use one very light spring on the advance. Engine starts at a small degree then flings out after 500 rpm to full advance. Easy to start any high compression engine. Also use a locking collar to allow no shaft up and down movement. I use a stock dist except when needing a tach drive.
Mike

Re: Locked out distributor advance question
 

I thought the Summit brand distributors like the ready to run type were MSD. I found a pack of Moroso brand distributor shims at a speed shop a few months ago.

Re: Locked out distributor advance question
 

I've been building distributors for 30 years, and no longer can find shim kits. If anyone knows please share. Thanks.

Re: Locked out distributor advance question
 

This^^^ I would never recommend a locked out distributor when using a stock or stock type distributor. I’ve been running my distributors with 18-20 degrees mechanical advance and all in by 2000 rpm for 25 years. The reward is no hard starting, no kickbacks, no broken flexplate teeth and no broken starter drives. Spins over like the plugs are out.

Re: Locked out distributor advance question
 

https://www.competitionproducts.com/.../#.XOEV0aR7mUk


Rick Thomason
GTOMayhem

Re: Locked out distributor advance question
 

When we used points (been doing this way too long) I simply used no springs. The load from the ppoints would pull the advance back out for easy start ups. Small throttle whack = full advance even at idle. EFI makes it much easier.

Re: Locked out distributor advance question
 

We class racers use an MSD timing control with fixed distributor. It'll take 15* or so out for starting. Also , we class racers sometimes use it to retard the timing in high gear.

Re: Locked out distributor advance question
 

This is a perfect example why 1319.5 E.D. Needs to hang out in the .90 neighborhoods....

Re: Locked out distributor advance question
 

Like the name... I call him YB E.D.