67 L79 Advance Weights

[Tom E.]

Which of the two advance Weights are correct for the 67 L79? I believe it is the one with he pointy end and appear older than the other set. When I rebuilt my original 111196 GM Distributor the heavier set was installed but in a separate bag of parts I found the pointy set which I believe are correct. I suspect someone was attempting to get the mechanical advance in a little earlier.
thanks Tom

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[Joe L.]

Re: 67 L79 Advance Weights

Which of the two advance Weights are correct for the 67 L79? I believe it is the one with he pointy end and appear older than the other set. When I rebuilt my original 111196 GM Distributor the heavier set was installed but in a separate bag of parts I found the pointy set which I believe are correct. I suspect someone was attempting to get the mechanical advance in a little earlier.
thanks Tom

[ATTACH=CONFIG]101068[/ATTACH][ATTACH=CONFIG]101069[/ATTACH]

Tom------


The ones on the left. I don't think the ones on the right are even GM weights.

[Tom E.]

Re: 67 L79 Advance Weights

Thanks Joe,
That was my guess and the ones on the left are the ones I am using. Appreciate the quick response. Hard to tell what the other set are, the original owner raced the car for a time so I got a bunch of non-OEM parts with it including Mallory dual point distributor among other things.
Tom

[Tom D.]

Re: 67 L79 Advance Weights

SUN MACHINE CHRIS K - 1.jpg
A Neighbor in MI has this old (Sun Electric, from Chicago, IL) machine working. One way to set up per GM's specs.

[Tom E.]

[Tom E.]

Re: 67 L79 Advance Weights

As a side note for anyone following this or looking for distributor info, when I first ran the car I left the original vacuum advance and springs in the distributor. The car ran well but seemed to lack what I felt as good low end throttle response. When checking timing it wasn’t all in until 3800-400 rpm. The original can held vacuum and was all in at 14 Inches which is insufficient to meet the 2 inch rule. Yesterday I replaced the can with a B26 which measured all in at 12 inches as well as replaced the factory springs with the black Mr Gasket springs. Wow, what a difference! The car really woke up and runs like one would expect a 350 HP 327 should run.
Tom

[Duke W.]

Re: 67 L79 Advance Weights

Do you mean a 12" B26 VAC? The B28 is all in at 8", which is more aggressive than necessary since with a correct L-79 cam or something close, idle behavior is 14" at 750, so the B26 passes the Two-Inch Rule.

A B26 VAC and the black springs in the Mr. Gasket 928G spring kit is what I recommend as a starting point for L-79s. The black springs should bring the OE 30 degrees centrifugal in by about 3000. Set total WOT advance at 38-40 and if it doesn't detonate you're done and will notice a considerable SOTP improvement in performance.

I agree with Joe that the weights on the right don't look like GM OE, but the set on the left are not the same. Note the hole at the end of one and the shape appears slightly different. AFAIK all GM OE setups used the matched sets of weights and springs, but it's okay IMO to use unmatched sets when fine tuning the centrifugal curve.

Duke

[Tom E.]

Re: 67 L79 Advance Weights

Duke,
Thanks for the correction, yes I meant B 26. And yes, I noticed the difference as well on the 2 weights but they work well so I used them. Who knows, I guess it’s possible they are both original, but as you know a lot can happen in 50 years!
however, if anyone reading this has a correct set I’m interested in buying them.
Thanks Tom

[Joe L.]

Re: 67 L79 Advance Weights

Duke,
Thanks for the correction, yes I meant B 26. And yes, I noticed the difference as well on the 2 weights but they work well so I used them. Who knows, I guess it’s possible they are both original, but as you know a lot can happen in 50 years!
however, if anyone reading this has a correct set I’m interested in buying them.
Thanks Tom

Tom-----


These are the weights your application is supposed to use. These appear identical to yours except that one of yours has an extra hole.I suspect that the extra hole in one of them is a means the factory used to assure the correct weight. In other words, if the thickness of the material the weight was stamped from varied on the high side within the allowable limits, it might have been necessary to add the hole to effectively remove some weight.


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[Tom E.]