Does anyone on the list know a source for a vacuum advance for a 67 430 with the correct advance specs? The generic ones that NAPA and other stores around here sell are supposed to be for all Buick V8's from 67-74 with only one application.
Carl, That's because they are all the same. They supply 14-18* at 16 inches of vacuum. If that is too much advance, it's a simple matter to make a plate to limit the advance to whatever you need. All Buick V-8 advance cannisters have the same specs from 67-74. If you modify your mechanical advance to come in earlier than the stock springs allow, it is wise to limit the vacuum advance to 8-10*, otherwise you will have too much total advance at cruising speeds, and that will give you ping and surging. If you have a totally stock distributor, the NAPA cannister is the right one.
I'm in the process of making a stop late for mine right now... I found all the hardware at the local home improvement giant. You can email me for specs on fabricating one, or you can email Dave the IgnitionMan on this board at sparkman451@earthlink.net Too much initial vacuum advance caused me a lot of heartache trying to find a miss in the engine. What a pain.
I know the vacuum advances are interchangeable for fit between 67-74's, but the NAPA book that I saw does not have an application for 67 430's. There is a listing from 68-74. As you know, 67 v8's used manifold vaccum for the advance, and Buick switched to ported vacuum in 68, so the advance might have changed. The NAPA application for 68-74 Buicks is VC1765, which starts at 5-7 inches, and has a max advance of 8@11-13. My 67 manual says advance starts at 6.5-8.5 inches and full advance is 14@16-18. I don't think the NAPA advance is correct for a 67.
Carl, I have a book called "The Guide to Buick GS 1965-75" It has distributor specs from 1965-71. All the vacuum advance canisters have the same specs according to this book. Advance starts at 6-8" of vacuum, 14-18* at 16" of vacuum. According to this book, your initial timing should be 2 1/2* BTDC. With full manifold vacuum advance, it would idle at 16-20*. Should be perfect.
Larry, actually there were a number of different vac diaphragms available. (listed in the factory manual) I used to but the 10 degree ones. I can gig up part numbers but they are most likely discontinued. Bruce BQUICK
Yup, But if you look at the specs in the chassis manuals and such, they're all the same. I would bet they are all discontinued too. Fortunately, it's easy to make a limiting plate to limit the amount of advance, and with the adjustable ones you can adjust the spring load to take the advance out when you dip into the throttle.
Correct NAPA part is VC680, and it will require the rubber tube degree stop over the pull pin. Specs: Vacuum levels, advance starts 8.0, to 11.0 limit, as measured in in/hg Identified with the universal build of B1, stamped on the mounting plate just behind diaphragm housing Sales number D1328 Note: ALL aftermarket vacuum advances have an ident numbering system that is universal to the aftermarket, stamped on them, as in the above "B1". If a Standard Blue Streak advance has a B1 on it, it IS the same spec as a Wells, NAPA, Borg-Warner, etc, that is stamped B1. This numbering system is different from the original GM ident. GM uses two numbers, left and right, in the same place on the mounting bar. Left number is the last three numbers of the GM part, right is either two or three number ident for the amount of DISTRIBUTOR degrees it will provide. Examples: Left: 419, last three part number numbers Right: 10, 20 distributor degrees available, 32 crankshaft Right: 024, 24 distributor degrees, 48 crankshaft The two digit right numbers will almost always need the rubber tubing stop for the pull pin to be in place to allow the vacuum advance to work correctly. Usually, the triple digit degree idents are designed for EGR valve equipped engines and are built for ported vacuum sourcing only, for those EGR equipped engines only, NOT for use on earlier non-EGR engines that utilize full manifold vacuum sourcing. Three digit EGR vacuum advances very, very rarely use a rubber tubing stop.
