1970 distributor differences

[D S.]

What are the differences between the 1111491 distributor and the 1111464 distributor? Just the vacuum advances? And the metal bands?

Thanks,
Scott Sims
Texas Chapter

[William C.]

Re: 1970 distributor differences

Vacuum advance, and the curve-491 is 13 @ 2500 and 7.5 @ 12, 464 is 11 @ 1600, and 6@ 12, completly different cam, springs and vacuum can.

[D S.]

Re: 1970 distributor differences

Thanks, Bill. Is the 201 16 vacuum still available and if not what is the replacement number?

[William C.]

Re: 1970 distributor differences

It's actually a 201-15 and is available as a reproduction, but what distributor are you trying to recreate?

[D S.]

Re: 1970 distributor differences

Just can't trust that JG to be right about anything. It said 201-16. A friend in California has a 1970 LT-1 that doesn't have the ID band on the distributor and he can't tell by looking if it is a 1111491 distributor. I'm trying to help him with it from here in Texas but I don't know how to identify distributors, either, unless they are stamped on the bodies.

[William C.]

Re: 1970 distributor differences

Just can't trust that JG to be right about anything. It said 201-16. A friend in California has a 1970 LT-1 that doesn't have the ID band on the distributor and he can't tell by looking if it is a 1111491 distributor. I'm trying to help him with it from here in Texas but I don't know how to identify distributors, either, unless they are stamped on the bodies.

Actually, the housings are the same, but the difference is in the autocam assembly and the vacuum cans. I've attached a picture of the vacuum can, The cams at the top of the mainshaft differ between part numbers as does the length of the slot in the autocam. You really need a distributor machine to recreate a curve.

[D S.]

Re: 1970 distributor differences

Thanks, again, Bill. I have learned a lot here from guys like you on the TDB.

I told the LT-1 owner that the distributor in it is likely the one that came with the car when built less the ID band. I suggested that he purchase a reproduction red band and that'll be that. I did ask him to get the numbers off the vacuum advance. That might help some. Or find an original authentic 491 distributor from the Driveline or something.

[Terry M.]

Re: 1970 distributor differences

Actually, the housings are the same, but the difference is in the autocam assembly and the vacuum cans. I've attached a picture of the vacuum can, The cams at the top of the mainshaft differ between part numbers as does the length of the slot in the autocam. You really need a distributor machine to recreate a curve.

Well actually the housings are all not quite the same. Testing my memory here, but sometime during the 1970 model year GM added a nylon bushing to the back end of the tach drive gear and drilled a pilot hole through the housing to locate that bushing. So the later housing had that additional hole through the tach drive pressure side of the housing visible from the outside. Astute judges will look for that hole.

BTW: I am almost certain the OEM 201 vacuum cans were stamped 201-16, but I will have to unearth the car to verify that, and that won't happen soon. I have other things to play with that are more fun, but when I get there I will be sure to send you a picture.

[William C.]

Re: 1970 distributor differences

Well actually the housings are all not quite the same. Testing my memory here, but sometime during the 1970 model year GM added a nylon bushing to the back end of the tach drive gear and drilled a pilot hole through the housing to locate that bushing. So the later housing had that additional hole through the tach drive pressure side of the housing visible from the outside. Astute judges will look for that hole.

BTW: I am almost certain the OEM 201 vacuum cans were stamped 201-16, but I will have to unearth the car to verify that, and that won't happen soon. I have other things to play with that are more fun, but when I get there I will be sure to send you a picture.

Terry. please take a look at the picture I attached in my post last nite, original unit, still on a distributor. I was aware of the button, but trying not to fog the general question with too many details as the "guts" including vacuum pot shaft etc are interchangible.

[Terry M.]

Re: 1970 distributor differences

Terry. please take a look at the picture I attached in my post last nite, original unit, still on a distributor. I was aware of the button, but trying not to fog the general question with too many details as the "guts" including vacuum pot shaft etc are interchangible.

I saw the picture. I can't rule out a typo between the car and the manual, but I will look -- when I get the chance. The old over the counter piece is more accessible than the car, but the car will tell us more. My priorities have changed recently and all this heartburn over manuals is now pretty low on my list. 9 times out of 10, or maybe more, we can't see the entire stamp on the vac can without removing the distributor cap anyway. So whether it is 201-15 or 201-16 doesn't matter too much, except for a lot of hot air on this forum.

[Terry M.]

Re: 1970 distributor differences

Terry. please take a look at the picture I attached in my post last nite, original unit, still on a distributor. I was aware of the button, but trying not to fog the general question with too many details as the "guts" including vacuum pot shaft etc are interchangible.

You are right Bill. All the 201 cans that I have (none for sale), including the one that came with the car (pictured), are 201 15. We will have to catch that on the next TIM&JG change. Both photos are with the front part of the distributor shield removed. Those of you with the 1969 style one-piece distributor box are SOL.

1970vacuum adv can 012.jpg

Just for S & G I tried to see the numbers on the can without removing the distributor cap. Here is the best I could do. There is no way to get the light in from the side to highlight the numbers. If you think judges can see this without the distributor cap coming off, or at least being raised as I did -- I have a bridge to sell you.

1970vacuum adv can 007.jpg

PS See, I didn't forget.

[Jim T.]

Re: 1970 distributor differences

Terry my 1970 original owner was built in July 1970. My Corvette's distributor does not have a pilot hole in the housing to locate a bushing. I would think that a 1970 July built Corvette would have this change.

[Terry M.]

Re: 1970 distributor differences

Terry my 1970 original owner was built in July 1970. My Corvette's distributor does not have a pilot hole in the housing to locate a bushing. I would think that a 1970 July built Corvette would have this change.

And I would expect that as well Jim. What is the date on your distributor tag? Perhaps they were scraping the bottom of the barrel with the 1971 models & distributors on the horizon.

[Jim T.]

Re: 1970 distributor differences

Terry my 1970's distributors tag has 0 C 26 and 1112020 imprinted on the tag. The engine is a 350/300 with turbo 400.

[Terry M.]

Re: 1970 distributor differences

Terry my 1970's distributors tag has 0 C 26 and 1112020 imprinted on the tag. The engine is a 350/300 with turbo 400.

Maybe it is better to consider the build date of the distributor, rather than the build date of the body. A March built distributor, such as yours would be less surprising lacking the hole for the plastic tachometer drive thrust bushing. It is however, a good data point that we should consider when re-wording the TIM&JG.