More Distributor Tech - Converting a Late F Engine Distributor to Vacuum Advance (3 Viewers)

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4Cruisers

4Cruisers

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After putting the project on the back burner for a while, I recently took a fresh look at converting a late F engine vacuum retard distributor to vacuum advance. This morning I wrapped up the project successfully :).

The approach I took was to modify an early 2F vacuum retard advancer so that it could be a direct physical replacement, with no modifications to the distributor itself, and to closely match the advance curve of the early F engine advancers. I had two good used retard advancers from 1/75 through 8/76 19100-61020 2F distributors and another in non-working condition. I cut the bad advancer up to determine what limits the actuator rod travel to ~2mm. It turns out there is a nut on a threaded shaft inside the outer can that can be backed off to allow for ~4mm of actuator rod travel, which equates to ~10.5 degrees distributor advance. I replaced the internal spring and adjusted its length until I arrived at the vacuum advance curve shown in the attached comparison plot. I then cut the J-arm off the F engine advancer and secured it to the shortened 2F advancer actuator rod.

When vacuum is applied to the vacuum nipple, which is on the inboard side of the diaphragm, the diaphragm pushes the J-arm against the stud on the breaker plate, rotating the breaker plate CCW and advancing the timing.

Here are photos of the prototype advancer and a plot comparing the vacuum advance curves of the modified retard advancer and the advancer (19220-60072) found in the early F engine distributor 19100-60042.

Retard Advancer 1


Retard Advancer 2


Retard Advancer 3


Advance Curves 2F Vacuum Retard versus 19100 60042
 
4Cruisers

4Cruisers

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I forgot to mention, the distributor I'm using as a test bed is courtesy of @ToyotaMatt, who also inspired me with his skunk works mentality for all of my distributor R&D.
 
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4Cruisers

4Cruisers

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This evening I pretty much completed my first modified and refurbished F engine vacuum retard distributor, 19100-60066, which has been converted to vacuum advance. The only thing left to do is to add the J-arm to the advancer's actuator rod. When finished, the advancer will look like the one in the above photos. If you look carefully at the second photo below you'll notice that I've also upgraded the breaker plate to the type used in the later non-US F engine distributors, which allows you to use the easier-to-adjust points found in the early (1/75 through 9/77) 2F distributors.

This is the cleanest and least worn F engine distributor I've run across. For example, there is just a tiny amount of side-to-side lateral play at the top of the distributor shaft, the shaft spins very smoothly, and the cam lobes show absolutely no sign of wear. New Toyota parts will include the distributor cap, rotor, points, condenser, terminal assembly, and distributor cap hold-down clamps. The shaft O-ring will be a new generic O-ring - the Toyota O-ring is NLA.

I'm planning on posting this distributor for sale in the MUD classifieds in the next day or two, but I'm always open to PMs before that.



19100 60066 1


19100 60066 2


19100 60066 3
 

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