NOS Vacuum Advance Can

[Larry T.]

I hate to ask because I am sure there are a lot of different opinions, but what is a fair price for an excellent to NOS VAC that I know works within the specified range? I guess these may be different in value, but lets say a 236, 355 or 360. I heve been looking for a couple of these and recently passed on a 360 I wonder if I should have picked up for around $100.

I have a 360 that is not working properly (starts at 10", all in at 15"), does it have any value? Can it be restored?

Thanks.

[Timothy B.]

Re: NOS Vacuum Advance Can

Larry,

What are the specs for the 360, I thought it's 12*@15". If so there is no problem with your 360.

I think 355 is 12*@12" and 236 is 15*@8"

[Larry T.]

Re: NOS Vacuum Advance Can

I wish that were correct.

The 360 is supposed to start at 7"Hg and have a max advance of 12* (crank) at 12" Hg.
The 355 is 5-7" to start and 16* at 11-13"Hg.
The 236 is 3-5" to start and 16* at 6-8".

So my 360 is basically coming in at 3"Hg more than it should from start to max advance.

[Mike M.]

Re: NOS Vacuum Advance Can

Larrytry calling Don Baker 815-498-9522. He's in Sandwich, IL. He restores vacuum cans depending on your model he may be able to help. He did one for my 65L79 and its great.

[Larry T.]

Re: NOS Vacuum Advance Can

Mike,

Thanks for the reply. I called Don. I am going to do him a favor and let anyone that looks at this know that he is not interested in restoring these anymore. Too labor intensive. Don was a very nice guy and very helpful with information.

He did suggest Dave Fiedler at TI Specialty as a possible source to restore a VAC.

Larry

[Mike M.]

Re: NOS Vacuum Advance Can

Larry I agree and excellent guy. That's to bad he does a excellent job. his price was good maybe to good I would have paid double.

[Wayne M.]

Re: NOS Vacuum Advance Can

...The 360 is supposed to start at 7"Hg and have a max advance of 12* (crank) at 12" Hg.....

Close enough to spec's in the Delco Test Specs book. Is there a possibility that your vac gauge is off-calibration by 3 degrees ? I'd try another instrument before acting.

.

[Duke W.]

Re: NOS Vacuum Advance Can

Try a little silicone spray lube on the plunger shaft and exercise the diaphragm with a vacuum pump. It may come back closer to spec.

Typical failure mode of the VAC is the plunger shaft seizing, which might be able to be fixed or a leak, usually due to a break in the diaphragm, which usually means the VAC is toast.

Remember that the whole VAC is only worth 3 points - two for originality and one for condition. If one has a replacement VAC I only consider it to be a one point deduction for a service replacement, so buying a NOS VAC for a hundred bucks is a pretty expensive point, and if the plating is severely deteriorated it's a one point condition deduction.

Duke

[Gene M.]

Re: NOS Vacuum Advance Can

.......... and if the plating is severely deteriorated it's a one point condition deduction. (partial quote)


Please set aside, but remember the deteriorated finish on the original part. A 20% max deduction is the guide line acceptance for finish. If it appears as correct type finish it would be in the condition area. If it is painted it would be originality.

I would "star" the line item and accumulate other minors (less than one point) to deduct a point. Always try to give any partial point in favor of the car. I did say car not owner.

[John D.]

Re: NOS Vacuum Advance Can

It is a royal pain in the butt and quite costly to restore an original VA. Involves many processes. Don has to send the parts all over the country to pull the resto off. That's why he doesn't do it anymore.
Unless your vacuum advance is extremely rare then it is not cost effective to have it restored.
Now say you have a 58 to 61 low HP FI distributor and it has the correct 134 can. Well then it should be rebuilt at all cost as this part is just not available.
Now say you need a nice 201 or 236 VA. Ask Don about these. But he doesn't deal with any others. Just the ones for TI and FI. His repro specs out perfect. I believe he stamps them also with the numbers. I know they will fly thru our judging and also go thru PV.

[Larry T.]

Re: NOS Vacuum Advance Can

This made me think of something. The VAC is on a distributor which has not been serviced in some time (maybe ever). Perhaps it is not the can at all, maybe it is the distributor. I will pull it off and recheck it, if it still does not hit spec I will try lubricating it and working it a bit.

Thanks,

Larry

Try a little silicone spray lube on the plunger shaft and exercise the diaphragm with a vacuum pump. It may come back closer to spec.

Typical failure mode of the VAC is the plunger shaft seizing, which might be able to be fixed or a leak, usually due to a break in the diaphragm, which usually means the VAC is toast.

Remember that the whole VAC is only worth 3 points - two for originality and one for condition. If one has a replacement VAC I only consider it to be a one point deduction for a service replacement, so buying a NOS VAC for a hundred bucks is a pretty expensive point, and if the plating is severely deteriorated it's a one point condition deduction.

Duke

[Larry T.]

Re: NOS Vacuum Advance Can

Wayne,

The best check I could make to the calibration was to take one that someone else verified with better equipment than I have and see how my mity vac compared. Mine was right on just a couple of weeks ago, so I think I am good there.

Thanks,

Larry

Close enough to spec's in the Delco Test Specs book. Is there a possibility that your vac gauge is off-calibration by 3 degrees ? I'd try another instrument before acting.

.

[Duke W.]

Re: NOS Vacuum Advance Can

This made me think of something. The VAC is on a distributor which has not been serviced in some time (maybe ever). Perhaps it is not the can at all, maybe it is the distributor. I will pull it off and recheck it, if it still does not hit spec I will try lubricating it and working it a bit.

Thanks,

Larry

The distributor is one of the most overlooked components on the car. There are probably many vintage Corvettes whose distributors have seen nothing more than points, condenser, and a few cap and rotor changes for over 40 years.

It's a simple device, but critical to proper engine operation, and most could probably use a good overhaul and "blueprinting", which is an easy job to do if the shaft bushings are okay.

The procedure is in the 1963 Corvette Shop Manual and late COMs.

Duke