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Hoping to get confirmation before I buy.
I am new to Corvette ownership. However I’ve owned some other old cars, so some things are the same.
Couple things.
As far as I know your Vacuum Advance Canister is bad if you can blow into it with no resistance, correct?
Second, is this the correct replacement? ECH VC1838
73 350 Auto
No modifications except Pertronix in my Delco distributor.
In your spring thread, you had "HEI" in the title. So what distributor do you actually have? HEI didn't go into C3s until 1975, but Pertronix Ignitor is almost always a points replacement.
Anyway, Lars' timing and distributor papers have a list of correct vacuum cans. You can also limit the advance in several ways to really fine-tune your ignition timing. If you suck on the vacuum can, the lever should move. And if you apply a vacuum, it should hold that vacuum (shown below). I don't know what blowing into it does.
If you haven't already, I'd start by emailing Lars for his papers, including his Q-Jet paper. Pick up a Mity-Vac handheld vacuum pump, a vacuum gauge, and a dial-back timing light and/or MSD timing tape (if you don't have them already), and then follow his timing instructions. It will really wake up your car.
From: At my Bar drinking and wrenching in Lafayette Colorado
I provided the OP with all info, specs, and tech papers on this subject 2 months ago. He has all the tech info and all the part numbers, and he knows which parts numbers are for HEI versus points distributors. He is also fully aware of the "2-inch rule" for selecting a vacuum advance, and knows how to pick one.
I am not well versed in a lot of what many others may be well versed in.
I thought since my distributor has the pertronix it is classified as HEI. Clearly that is not the case.
You'll have to forgive my ignorance, I'm working on it.
I’ve received a lot of papers from Lars, including tuning, timing, vac advance, and a couple others. Lars has been very helpful and patient when emailing back and forth with me.
The paper I received from Lars on vac advances, confuses me a bit. That’s a little embarrassing to admit, (along with the HEI goof), but it’s the truth.
There are so many different vacuum advance units, all of which seem to be a little different under vacuum. So, I was hoping to get some help as to where to start, a good unit I can bolt on and go.
It’s been at least five years, give it take since I’ve worked on a car pre 73, and I’ve never owned a SBC. Some of my questions may be elementary, but that’s just where I am, for now.
Thank you all for your help, it is very much appreciated.
I am not well versed in a lot of what many others may be well versed in.
I thought since my distributor has the pertronix it is classified as HEI. Clearly that is not the case.
You'll have to forgive my ignorance, I'm working on it.
I’ve received a lot of papers from Lars, including tuning, timing, vac advance, and a couple others. Lars has been very helpful and patient when emailing back and forth with me.
The paper I received from Lars on vac advances, confuses me a bit. That’s a little embarrassing to admit, (along with the HEI goof), but it’s the truth.
There are so many different vacuum advance units, all of which seem to be a little different under vacuum. So, I was hoping to get some help as to where to start, a good unit I can bolt on and go.
It’s been at least five years, give it take since I’ve worked on a car pre 73, and I’ve never owned a SBC. Some of my questions may be elementary, but that’s just where I am, for now.
Thank you all for your help, it is very much appreciated.
Eric
No worries! Please keep asking questions. And post some photos, too. You'd be surprised what folks can spot.
Someone would have noticed the distributor. If you only use the springs, I don't know that it matters much which kit you buy, as long as you can find a set of springs to get you the result you want (per Lars' papers).
Correct Distributor Vacuum Canister?
