Even More Distributor Tech - Early F Engine Vacuum Advancers

4Cruisers

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This weekend I decided to test the nine remaining early F engine vacuum advancers in my stash, and to find an easy and reliable way to adapt the 1/8-inch copper tubing fitting to accommodate OEM vacuum hose.

My initial surprise was that all nine had diaphragms that work and hold vacuum. It turns out that two have very stiff diaphragms - I can't even get 10 degrees of distributor advance from them, even after removing the internal spring. I proceeded to adjust the other seven to obtain acceptable vacuum advance curves. It seems to me that the later NipponDenso advancers didn't use the same quality rubber in the diaphragms, a lot of the newer used advancers I've run across have failed.

A year or two ago I tried to find a source for the copper tubing fittings, a type of flare fitting, that Toyota used for connecting and sealing the copper vacuum tubing that ran from the carburetor to the distributor. I looked at early Volkswagen Beetle fittings, but they're a different thread - same with similar fittings used on early domestic vehicles. So this weekend I took a fresh look. It turns out the thread is M8 X 1.25 :doh:. For the first of the new batch of modified advancers, which will be installed in a 19100-60042 distributor I'm refurbishing for @CRZR45, I used a new yellow zinc plated FJ60 bolt I had in my bolt stash. I cut it to length and drilled a 5/32-inch hole all the way through. Then I inserted a 23mm long section of 5/32-inch brass tubing using a small amount of JB Weld to secure in in place and seal it. I screwed it into the advancer after installing an 8mm ID rubber O-ring (Danco #6). I just finished testing it out and it works great :). I have some M8 X 1.25 brass plugs in my McMaster-Carr shopping cart that I'll use for the remaining advancers.

Here are photos of the unique OEM fitting and the completed vacuum advancer, ready to install into the refurbished distributor.

Vacuum Advance Fitting.jpg


Early Denso Advancer.jpg
 

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