View Full Version : 352 vacuum advance
05-12-2011, 09:11 PM
According to the Ford manual, the 352 distributor asks for 0-3 degrees vacuum advance starting at 5 psi vacuum, and by 15 psi vacuum it is in fully at 8.5-10.5 degrees.
Does anyone have any information on the BWD VC309 vacuum advance unit which looks like the replacement unit of choice? I do not see any specs published for it that I can find and I'm wondering if it can meet the Ford specs by adjustment. If anyone could say they've successfully used it and are happy with the performance would be useful also.
05-30-2011, 11:04 PM
I finally got to work on the vacuum advance again and here is what I found: The advance on the rebuilt distributor that I installed started at 5 psi vacuum and was full in by 10.5 psi. I couldn't get it to adjust to anything different with the hex wrench. I did order a new one which I received this week and it was setup approximately 3 turns out. The vacuum started moving the link at 6 psi and it was in fully at 15 psi. This is what the Ford specs are for the 352 engine. I installed the new vacuum advance and reset the initial timing which I had retarded in order to reduce the pinging. The new vacuum can made a world of difference! The pinging is gone, power is significantly improved and with the advance at idle it is running cooler! The picture below is of my wife driving the Tbird for the first time. The grin says it all!
05-31-2011, 01:09 AM
Jim, she's beautiful.
I find that MOST vacuum diaphragm units don't work in these old engines. I have one to change, too.
05-31-2011, 11:11 AM
I had ASSUMED that if you had an intact diaphram that you could get the vacuum advance to work correctly by adjusting it. Not the case as the spring/screw can evidently come apart inside so this is another failure mode. I would highly recommend a vacuum hand pump with a gauge like a Mighty Vac to adjust anyone's vacuum advance. Without one, you are just working with trial and error and if there is something wrong with it, you won't be able isolate it to that part.
The 352 can be set up to run with plenty of power once the valve timing, ignition timing including centrifugal and vacuum is set up correctly.
Now I need to start working on that disk brake conversion so that I can get this baby stopped with all this power!
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