Weld on distributor pole piece correct?

[Mark G.]

I took apart my 69 L71 1111928 distributor to remove some shaft endplay and noticed this weld on the rotating pole piece. Is this something GM did back then? Should I remove the weld? When I run this on a Sun machine, what would be a good number for total mechanical advance? Is this the correct part for this distributor?

[Terry M.]

Re: Weld on distributor pole piece correct?

I took apart my 69 L71 1111928 distributor to remove some shaft endplay and noticed this weld on the rotating pole piece. Is this something GM did back then? Should I remove the weld? When I run this on a Sun machine, what would be a good number for total mechanical advance? Is this the correct part for this distributor?

Mark

It has been some years since I was that deep into my 1970 TI distributor, but I don't remember such a weld there. Let's see what others with access to original TI distributors have to say. I doubt your 1969 distributor in its original configuration would be any different than any other original TI distributor. Unfortunately my 1970 is several thousand miles from me at this time, so I can not go and check in the short term.

Have some patience.

[Joe L.]

Re: Weld on distributor pole piece correct?

I took apart my 69 L71 1111928 distributor to remove some shaft endplay and noticed this weld on the rotating pole piece. Is this something GM did back then? Should I remove the weld? When I run this on a Sun machine, what would be a good number for total mechanical advance? Is this the correct part for this distributor?

Mark-----

The weld is not original. This looks like it might have been done to "repair" a previous modification (i.e. previous elongation of the slot). I don't know why anyone would have wanted to elongate this slot but you might be better off leaving the weld as-is.

[Mark G.]

Re: Weld on distributor pole piece correct?

Thanks, Joe. I thought it wasn't stock. I'm thinking I should replace it. Are the reproductions ones any good or should I try and locate a GM one?

[Leif A.]

Re: Weld on distributor pole piece correct?

Looks like it was put there to limit advance. How did the car run at idle and at speed before you took it apart?

[Mark G.]

Re: Weld on distributor pole piece correct?

Not as good as I remember from years ago. The car idles at around 12 inches @ 900 rpm. What triggered this was reading about converting to manifold vacuum for the vacuum advance. I had to remove the distributor to change the advance can and noticed the weld. Other than shimming out some shaft endplay, I also noticed that the dimple on the gear was opposite the rotor tip. We ran it on a distributor machine last Saturday and only got about 9* distributor advance. Any idea as to what total mechanical advance I should shoot for using a Sun distributor tester? I think 18* is the number I read, but not 100% sure on that.

[Joe L.]

Re: Weld on distributor pole piece correct?

Thanks, Joe. I thought it wasn't stock. I'm thinking I should replace it. Are the reproductions ones any good or should I try and locate a GM one?

Mark------

I don't know anything about the reproduction pole pieces except that they seem to be available.

NOS GM are out there but usually sell for big money. However, I really think the one you have is OK. The existing slot with the weld looks to me to be about the configuration of the original slot.

[Duke W.]

Re: Weld on distributor pole piece correct?

The OE centrifugal specs are in your CSM and AMA specs. I'm not sure about '69, but the '67 L-71 is start @ 900, 30 @ 3800. In order to achieve the 36-40 total WOT advance recommended in the Chevrolet Power Manuals, you would need to run initial in the range of 8-10. Whether or not the engine will tolerate the above centrifugal and initial range is a function of actual compression ratio, which most owners have little or no idea of what it REALLY is, and fuel octane, so it's usually a matter of experimentation. Typical L-71 idle vacuum in my experience is 14" @ 900, so you may have a higher than OE overlap cam and you will need to use a 8" B28 VAC.

[Mark G.]

Re: Weld on distributor pole piece correct?

Thanks Duke. My car idles around 12" @ 900 with the vacuum advance disconnected. I have a B26 advance now, so would the B28 be a better choice? I talked with Dave at T.I. Specialty and he is sending me a NOS pole piece. Based on our conversation it is going to be a 538 unlike the 540 that came in the car.

[Duke W.]

Re: Weld on distributor pole piece correct?

With full time vacuum advance that brings total idle advance into the mid-twenties range, vacuum at 900 should be a little higher, so give it a try and see how much more you get and check that the total idle advance is in the correct range and stable. I recently purchased a B26 (Standard VC-181 on Amazon, about 12 bucks) as a birthday present for a friend with a '67 L-71. It started at 6" and was all in at 12.5". So try the B26, and if it doesn't work out go with a B28. The B28 has been out of production for some time, but recently there is still stock in the Airtex brand, 4V1053.Duke

[Gary C.]

Re: Weld on distributor pole piece correct?

Mark,
Attached is picture of 540 Rot PP showing dimensions.

Gary

[Mark G.]

Re: Weld on distributor pole piece correct?

Thanks Gary. I can use your picture to remove the weld so the slot is the correct length.

[Gary C.]

Re: Weld on distributor pole piece correct?

Mark,

Specs are:
0 deg @ 450 rpm
6 deg @ 1000 rpm
11 deg @ 1500 rpm
15 deg @ 1900 rpm

Rpm in Sun distributor machine. Double it for actual rpm.

Gary

[Mark G.]

Re: Weld on distributor pole piece correct?

That's with the 540 pole piece?

[Gary C.]

Re: Weld on distributor pole piece correct?

For distributor 1111928 which has 540 Rot PP