L-72 distributor questions

[Glen C.]

I'm in the process of "bringing back" a 66 L-72 which has not been cranked in years. The engine will turn by hand, so the next thing on my list was the unidentified (no band) "bound up" TI distributor. I would like to have this distributor identified and if possible make it compatible to this engine using the original TI amplifier, TI coil and observe the "two inch rule". The following numbers are on the dist. components.
Main distributor shaft #171, Cam #542, Vacuum can. MS 360 12. The vacuum can will not hold vacuum, so it will need to be replaced. There are no identifying numbers/markings on the weights/springs. The internal magnetic coil assembly appears to be an original with the thin white & white/green wires. The rest of the parts appear to be the same as any non TI mid year dist. The engine looks mostly stock, 069 intake, 858 heads, 827/828 exhaust, 3247 Holly, etc. I addition, I would like to know what lube is used in the top bushing cavity, and is there an additional substance such as cotton or felt that retains the lube? The parts catalogs that I have looked a do not show any part that is used in this area. Thanks in advance!

[William C.]

Re: L-72 distributor questions

There is a special lube used to fill the pocket under the plate that holds the pickup coil assy, and the cavity is topped with a plastic seal and felt washer on top of that. The MS 360 12 is all in at about 12 inches of vacuum, with 6.5 degrees of Distributor advance (13 degrees crank) not a bad choice if it worked, but there are many discussions of alternatives in the archives. Normally there is up and down movement in the shaft by design, so with a little soaking time and gentle pursuasion in the up-down axis of the shaft, it should free up. Check the TI components for cracks in the winding and resistance, and it should be salvagable.

[Glen C.]

Re: L-72 distributor questions

Thanks Bill, for the quick response. I was able to get the shaft out of the dist. housing with liberal amounts of PB Blaster. The parts cleaned up rather well and show minimun wear. I was going to order the small component rebuild kit and the brass button that goes in the tach drive cavity. This kit has the seal piece that you mentioned. When it last ran the fuel was usually mixed half & half, 92/93 octane and "Turbo Blue". I'm pretty sure the vac. can. must have worked back then & has probably deteriorated from setting. Do you know where I can get the special lube? The old lube appears to have some other substance mixed with it, but I don't know if the consistency has changed over the years. It is almost like a paste. I did look in the service manual, and it indicates that the upper bushing has a permanent type lubrication, and requires no periodic maintenance. Thanks again!

[William C.]

Re: L-72 distributor questions

The lube is generally available on the Internet Flea Market, in Delco containers (one will last a lifetime) Original distributors did not use a thrust bushing on the crossgear, and if your housing shows no wear in the pocket where the crossgear rides then none is necessary. There are some tricks to installing the bushing so it is not detectable, email me if that becomes a necessity. The "goop" from Delco surrounds the upper bushing and provides some lube thru the porus bronze.

[Glen C.]

Re: L-72 distributor questions

Bill, Further reading in the service manual indicates that a SAE 20 oil should be added to the "packing in the cavity". I'm not sure that using this old "packing" is going to work well.

[Duke W.]

Re: L-72 distributor questions

There's no direct replacement for the 360 12 VAC, and the closest replacement is the B20/26 that has 16 instead of 12 degress crank advance at 12". I don't know of any other applications for the 360 12, so it's probably the original distributor.

Assuming you have the OE camshaft a 12" VAC meets the Two-Inch Rule with full time vacuum advance.

I also suggest you change the ported vacuum advance to full time. This has been discussed countless times for L-72 and L-71. Cooler running and lower fuel consumption in normal urban traffic are the two big benefits.

The special GM distributor and starter motor grease is long discontinued. A photo of the tub was posted in a recent thread. As a replacement, I suggest a full synthetic NGLI #2 general purpose grease.

Distributor shafts can sometimes be difficult to remove due to the development of a burr at the roll pin hole. Rather than forcing it, dressing the hole ends lightly with some 400-600 paper will quickly remove any burrs.

Grease is a combination of a solid "soap" and oil. Once the oil drains/evaporates what is left is the solid soap from the original grease.

The upper bushing grease well doesn't need regular service, but they probably didn't consider that many of these cars would still be in service after over 40 years.

Maybe we should change the distributor service requirement to "remove, disassemble, clean, relubricate, and test the centrifugal and vacuum advance mechanisms once every 30 years whether you think it needs it or not".

Duke

[Glen C.]

Re: L-72 distributor questions

Sorry Bill, I responded B4 reading your last response. I'll check the internet for the lube. Thanks for mentioning the no brass button on original dist's. I thought I lost it during the cleaning process. I'll email you when I get to that point, as my svc. man. gives no adjustment procedure for the tach cross shaft, or a test procedure for the mag pick up assembly. Thanks, Glen.

[Joe L.]

Re: L-72 distributor questions

There's no direct replacement for the 360 12 VAC, and the closest replacement is the B20/26 that has 16 instead of 12 degress crank advance at 12". I don't know of any other applications for the 360 12, so it's probably the original distributor.

Duke

Duke------


I think there is a replacement for the GM #1115360 vacuum control. It's a "B10" stamped control and can be purchased under Delco #D1383X, aka GM #19138049. This is not a CATALOGED GM supercessive part number but I believe the specs are virtually identical if not absolutely identical.

So, why isn't it a cataloged supercessive part number? Well, that's because the GM #1115360 was discontinued many years ago without supercession. The GM #19138049 came along much later and GM does not usually "reverse" discontinuations without supercessions.

[Glen C.]

Re: L-72 distributor questions

There's no direct replacement for the 360 12 VAC, and the closest replacement is the B20/26 that has 16 instead of 12 degress crank advance at 12". I don't know of any other applications for the 360 12, so it's probably the original distributor.

Assuming you have the OE camshaft a 12" VAC meets the Two-Inch Rule with full time vacuum advance.

I also suggest you change the ported vacuum advance to full time. This has been discussed countless times for L-72 and L-71. Cooler running and lower fuel consumption in normal urban traffic are the two big benefits.

The special GM distributor and starter motor grease is long discontinued. A photo of the tub was posted in a recent thread. As a replacement, I suggest a full synthetic NGLI #2 general purpose grease.

Distributor shafts can sometimes be difficult to remove due to the development of a burr at the roll pin hole. Rather than forcing it, dressing the hole ends lightly with some 400-600 paper will quickly remove any burrs.

Grease is a combination of a solid "soap" and oil. Once the oil drains/evaporates what is left is the solid soap from the original grease.

The upper bushing grease well doesn't need regular service, but they probably didn't consider that many of these cars would still be in service after over 40 years.

Maybe we should change the distributor service requirement to "remove, disassemble, clean, relubricate, and test the centrifugal and vacuum advance mechanisms once every 30 years whether you think it needs it or not".

Duke

Duke, I was hoping you would chime in on this thread. I've read many of your responses re: two inch rule. You are right about the every 30 years lube cycle. The shaft has been removed, no burrs. Thanks for the grease suggestion. It still has the solid lifters, push rods, rocker arms etc. probably an original grind cam.
Here is an additional question. Earlier today I checked the vac. can. on my 64 327/300 PG, AC Vette. It has a #201. If I understand correctly the #201 is not the ideal vac. can. for this vehicle with powerglide. That said, the #201 may be a better substitute for the L72 if it is converted to full manifold vacuum. You see where I'm going with this? If this is true I will move the #201 to the L72 & buy a more compatible vac. can. for my 64 327/300 PG Vette.

[Duke W.]

Re: L-72 distributor questions

No, the 201 requires 15-16" to pull for the limit, so it doen't meet the Two-Inch Rule for an engine that idles at 14". To meet the rule you need a 12" or less VAC.

The 201 15 is okay for a 327/300 with a manual transmission.

It may not meet the Two-Inch rule with Powerglide idling in Drive at 450-475.

So how about checking idling in Drive vacuum - or anyone with a base engine/Powerglide.

For '66 the 327/300 VAC was the 355, which is 16 @ 12". Maybe there's is a message in that change.

Duke

[William C.]

Re: L-72 distributor questions

The packing I believe is only the felt ring that goes right under the movable breaker plate.

[Glen C.]

Re: L-72 distributor questions

No, the 201 requires 15-16" to pull for the limit, so it doen't meet the Two-Inch Rule for an engine that idles at 14". To meet the rule you need a 12" or less VAC.

The 201 15 is okay for a 327/300 with a manual transmission.

It may not meet the Two-Inch rule with Powerglide idling in Drive at 450-475.

So how about checking idling in Drive vacuum - or anyone with a base engine/Powerglide.

For '66 the 327/300 VAC was the 355, which is 16 @ 12". Maybe there's is a message in that change.

Duke

I guess I'm confused, mostly between the GM numbers & the NAPA numbers & other suppliers. One parts house lists the #201 for all 63, & 64-65 250 & 300, & 65-67 425 & 435. More than likely, they are assuming ported vacuum with this statement. If the #201 is not the best choice for the mostly stock L72 with full manifold vacuum which vac can do you suggest? I'm ready to buy! Thanks again.

[Wayne M.]

Re: L-72 distributor questions

I'm in the process of "bringing back" a 66 L-72 which has not been cranked in years. The following numbers are on the dist. components......
Main distributor shaft #171, Cam #542, Vacuum can. MS 360 12. ...

Glen -- any chance your '66 L72 is a late production car, with (maybe) an original 360_12 can ? There was some discussion yesterday or so that this distributor 1111093 had more than one vac advance number factory installed over the production life of 1965 and 1966.

P.S. does your lower shaft cast housing have the partially filed and machined oil annulus, as shown on the left in the pic below ?

[Donald L.]

Re: L-72 distributor questions

The NAPA VC1765 (B20 or B26) is the best unit for either the PG 327-300 or the 427-400 as both engines pull about 14" Hg @idle and for the PG 300 in drive. The VC 1765 fully deploys @12" Hg.

[Duke W.]

Re: L-72 distributor questions

I guess I'm confused, mostly between the GM numbers & the NAPA numbers & other suppliers. One parts house lists the #201 for all 63, & 64-65 250 & 300, & 65-67 425 & 435. More than likely, they are assuming ported vacuum with this statement. If the #201 is not the best choice for the mostly stock L72 with full manifold vacuum which vac can do you suggest? I'm ready to buy! Thanks again.

The parts house is wrong. The 201 was OE on all '63 engines and L-71, but not the others you listed.

If you don't convert to full time vacuum advance - but why on earth would anyone not do this given the benefits - you can use just about any VAC with 16 deg. or less advance because the Two-Inch Rule doesn't apply since there is no vacuum advance at idle, which is why such engines will run hot and get lousy intown fuel economy.

Regarding Joe's post, I've got the "B10" penciled into Lars Grimsrud's list - 0 @ 7" , 12 @ 12", so this may be an exact replacement for the L-72 OE 360 VAC.

My hand hand written notes that show a NAPA part number of VC-1765SP, but I don't know the source of this data.

On a note of caution, some specs list distributor degrees and some crank degrees. In not sure if the "12" is dist or crank. If it's distributor, the crank advance is 24 deg., which is way too much. Someone is going to have to buy one and test it.

All of the specs in Lar's list are DISTRIBUTOR degrees.