Good Vacuum Canister?
 

Anyone know of any current part#’s to a good vacuum can for a HEI distributor on my 68 400? I seen some old articles around the web recommend a Echlin VC 1810 because it activates at a fairly low vacuum to go with a decent cam but it is no longer offered and am having trouble finding a superseded part#?

Car is idling hot and has no vacuum advance hooked up and would like to give that a shot hooked to manifold vacuum? Has a Cold Case Rad, Flowkooler Pump, and heavy duty 19” Flex Fan, and has no issues while moving, but stop for very long at stop lights etc, she starts climbing quick?

Any knowledge is appreciated.


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Here's a link that provides specification info on GM vacuum canisters. The first three pages are tech and then there are pages of canisters and their specs. It was written by "Lars" who's has done a lot of ignition tech on the GTO forum site.

https://www.crankshaftcoalition.com/...ance_Specs.pdf

https://www.gtoforum.com/forums/1964...ne-tuning.170/

That list is pretty good. I went with the 1703 because I didn't want a ton more advance. My HEI already had too much mechanical advance. It was as advertised within a degree or so. I have since switched to a better distributor.

Sadly many of the more desirable VA canisters have been discontinued, so the list from Lars isn't as good as it used to be.

I have several that I use here that are still available or were last year, but not doing a lot of that sort of work these days and it's been a while since I've bought any so they may be NLA as well......

When I was shopping for them I don't remember seeing more than one of the part numbers (From the crankshaft coalition list) that I couldn't get. Mostly from Napa. They did vary in price a little IIRC. Ive bought two of them. One for my HEI that I mentioned and one small cap points style unit that went into my billet distributor. Its cannister develops a leak from dry rot when I lived in So cal.

Try a Standard VC-262 fromOreilleys they’re still available.

You’re welcome

are the adjustables any good? i am pretty sure they still make them, crane and accel i think?

Adjustables are what I use these days because of what has been mentioned, the good numbers are drying up.

However I don't recommend tossing on an adjustable and running with it. They don't actually work properly when installed per instructions, which tell you to put the cam key on the outside of the rod to limit travel. That's actually the wrong side. And cranking in the screw not only limits when the unit starts working, it also shortens the amount of timing. Problem is that when you shorten it up to about 10-12 degrees it takes about 20 inches of vacuum to move the darn thing and it becomes useless. So when you loosen the screw so it starts working, it also increases the amount of timing it adds at the same time. So by the time you get the unit to start working at say 8 or 10 inches of vacuum it spreads out and increases the amount of timing it adds and starts throwing in 20-25 degrees, you don't want that either.

What I prefer to do with them is weld the slot on the inside of the rod (towards the canister side) to limit travel to about .200" to .250". This will give you about 10-12 degrees of additional vacuum advance and will not add any more no matter where you set the spring tension.. I then adjust the screw, usually closer to the lightest spring setting and test with a vacuum gauge, and usually shoot for the curve to start around 6-8 inches and end around 10-11 inches.

Of course this can be both delayed and lengthened by tightening the screw but I find these settings work pretty well both at high elevation and sea level. basically works like the B-26 or B-28 can and works very well with high duration camshafts.

By modifying these, welding the slot and setting up the spring tension, you can pretty much mimic any of those cans that were once available.

Matter of fact I just had to do this on my MSD distributor. It came from MSD with a points style B-26 can on it, and the diaphragm finally ruptured after 25 years of use. Now has a modified adjustable on it that works perfectly, actually works better than the previous cam because I can adjust the sensitivity to better suite the engine vacuum and the elevation I'm running.

These things are so highly misunderstood.

One of these days in the near future, when I have to setup another one, I'm going to make a video to show exactly how these things should be modified and setup to work well. In the mean time here are some pictures.

First picture is how I had a distributor come in here that someone setup.
It had a B26 can on it, but then someone also put a limiter cam on it to try and shorten travel. Not sure why you would even need to shorten a B26, they only toss in about 8 degrees anyway.
I later found a plastic advance bushing laying in the bottom of the distributor, likely fell out during operation, and had a pinging issue, and was bandaided by trying to limit vacuum advance. Another reason why the plastic bushings should not be used. Either solder in a brass bushing or weld the breaker plate, as I'll show in a minute.

Knowing this engine combo was getting changed around, I decided to start from scratch and modify a Crane unit. Second picture is the slot welded to limit travel toward the rear of the unit, then a might vac is used to test where I want the spring tension set to start pulling the unit based on where the engine makes vacuum. In the end it was similar to a B26, starting at around 6 inches of vacuum, but I had an additional 12 degrees of timing added to work on top of the 34 total where this engine made best power on the dyno for a safe light throttle cruise timing curve. Last couple of pictures are the breaker plate modifications made, checking the movement with a small degree wheel, then multiply by 2 to get your centrifugal advance, file as needed until desired number. No more plastic bushing to get brittle and fall out. This particular engine was also 10:1 with iron heads and runs perfectly on 91 pump gas.

Boy, thanks a million guys!! Sure appreciate it!!
Fairly new to a lot of this, definitely a newb when it comes to distributors!!

I may try that VC262 from Oreilly or order a adjustable Crane unit and set up as shown in previous post and play around, would be great to get this thing idling with out getting hot!!

Happen to know any of the specs of that VC262? I assume that is for a HEI?

Thanks Again[emoji120][emoji120]!!


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