Vacuum Advance For 1111258 TI

[Duke W.]

Re: Vacuum Advance For 1111258 TI

All cars sold in California in 1966 and 1967 had to meet the same proportional tailpipe HC and CO standards, and from what I can discern all 1967 Corvettes sold in CA had K-19, and I think all K-19 engines had ported vacuum advance.

Look at the NCRS Spec Guide. The 300, 350, and 390 HP engines had specific carburetors with K-19, but L-68/71 did not have specfic K-19 carbs, and all were set up for ported vacuum advance

My guess is that on these low volume engines, Chevrolet didn't want the hassle of dealing with several more carburetor numbers, so they used the California center carburetor on 49-state engines, too. Nevertheless, the total carb part number count for 1967 is ten including the L-68/71 end carbs, which are the same part number - both positions, both engines.

Duke

[John D.]

Re: Vacuum Advance For 1111258 TI

Confusing post and I should butt out of it but here's a little repeat, etc info on VA's.
Chevrolet/Delco made a lot of problems for us over the years. Reboxing others VA's and giving them a part number for the real deal.
For example: Be careful buying a NOS 1116163 or D1328 Vacuum control on the auction sites. Typically the can itself is stamped B1. POC.
Anyone wanting correct 201's they are available in reproduction form and are dead nuts. Each one is tested and is to exacting specs. See Don Baker for those. If you need a 163 though he doesn't have those.
If you need nice 236 15 or 16 (forget) then Don has those also. They are drop dead gorgeous and will pass any kind of judging.

I have seen BB distributors with the 163 vacuum advance.

Be careful as not all 201 vacuum advances are created equal. For example a 63 Fi,etc 201 can has a two piece front to it. Jorjorian and JD have discussed this.(I learned this from Don Baker). Two piece means the tube that the rubber hose connects to-the tube is soldered on to the can. Later SR 201 VA's the tube is part of the canister.
B1, B3, B5, B20, B22, B28. etc. Everyone of them has a different spring tension inside. A B1 has more spring tension that say a B28.
But a B5 has more spring tension that a B1. Go figure.

[Duke W.]

Re: Vacuum Advance For 1111258 TI

Like I said, if you are willing to take a ONE POINT HIT for an OE replacement VAC you only need to pick the B20, B22, or B28 depending on your engine/transmission combination.

That makes it pretty simple. A random selection gives you a 33 percent chance of getting it right, and a little research in the archives will make it 100 percent.

Duke

[Richard M.]

Re: Vacuum Advance For 1111258 TI

John, Michael, Duke, Tim, et al.......I have been studying all of this and have grasped most of it. Just want to say thanks for all of the info presented. It's been like a crash course of sorts for me out of necessity. I've learned much.

Over the last few days I've spent much time reading, researching, learning and digesting it all. Kindof left me with a bit of a headache I've absorbed so much. Like in the past career days of designing, simulating and testing built-in-self-test digital logic for microelectronics used in computers and large scale network processors. Somehow that was always easy for me, and grasping all of this is a little more complicated for me, if you can believe that.

I never tried to really understand all of this before as I never had a need, but now I need to so I've forced myself to learn.....and this task has been quite rewarding for me. I now have confidence.

I expect the rebuilt 427/435 engine to be delivered this week. Original carburetors also presently being rebuilt, are due in early next week. When I get them I'll start another thread with some photos and will get ready to modify the carb for the manifold vacuum modification. I'll need some assistance showing what I need to do then. Duke, I'll take photos for your article if you'd like.

Rich

[Duke W.]

Re: Vacuum Advance For 1111258 TI

Sounds like a plan. We'll co-author the article.

Duke

[Timothy B.]

Re: Vacuum Advance For 1111258 TI

Richard,

Now that you have the carburetor bug, read some articles on how to tune the holley and you will really be pulling your hair out.

That's why tuners tell you to change one thing at a time so you can go back if the results are not satisfactory. I can send you some pics of a Holley base with factory drilling for full manifold vacuum port to give a guide if you do the mod.

I have a nice tuning article found on google but I don't want to post it without permission from author.

[Richard M.]

Re: Vacuum Advance For 1111258 TI

OK Duke I'll get in contact with you when I get all set up. I'll check with Vinnie for preferred picture resolution, etc. A while ago he told me he has a good backlog of articles to last him through the fall. I owe him a article on my C1 seat track repair. I have good macro capability on my camera and even a micro tripod for great close-ups which should help.

Tim, yes certainly please send me any info you have to get me even more educated. Some photos would be great. You can send to richmzatcomcastdotnet.
I think if you found something on Google it's fair game. I've authored a few things and people have contacted me about using them. All I ask is proper credit if it's used in print elsewhere. I'd expect that author to ask the same.

What's your opinion of the book, "1967 External Carburetor Adjustments" here at the NCRS store? Does it cover the 3x2's? I was thinking of getting one.

Rich

[Timothy B.]

Re: Vacuum Advance For 1111258 TI

Richard,

I can't comment on the book as I have not read it. It's probably a good idea to buy because you can only learn more about tripower.

Staying with factory specs is the best with any carburetor but this vacuum advance mod IMO is something to consider.