I have a 3.4 liter PR V6 from a 94 Camaro running a 390 CFM Holley model 8007 4 barrel carb on an Edlebrock intake.
I have an HEI vacuum advance distributor and when I have it hooked to full vacuum it runs really well for about a week, then it kills the vacuum can. On the last one I found gas inside the can when I took it off the distributor. I have not had this problem when I have run the vacuum advance from a ported source but the car has much better throttle response when hooked up to full vacuum so I would like to resolve this issue.
The first can it ate was the original one on the distributor and I chalked that up to it just being old, the second one was an adjustable Crane unit so it was brand new.
For now I have the car running without vacuum advance and it is a slug at part throttle cruise so I would like to fix this as soon as possible.
Thanks in advance.
Rich

 

I used to work at a warehouse where we were a distributor for Crane, etc... all the go-fast stuff.

In the warranty pile was always a mountain of Crane adjustable vacuum advance units. I think you just had bad luck with yours, along with a lot of other people.

 

I wondered if maybe I had gotten a bad one. The confusing part was how did I get gas out of the vacuum port on the carb and how did it travle all the way down the hose into the vacuum diaphragm. I am assuming the gas is what killed the diaphragm.
I am going to install another one tommorrow and see what happens.

 

I found the problem. One of the o-rings on the fuel transfer tube from the metering block to the main body was leaking gas down into the port area for full vacuum. I think when the vacuuum would fall and the can would close it was sucking gas back into the advance can and the gas was eating the diapraghm.
I re-built the carb yesterday and the problem is gone.
Richey