65 240 in my F-100. With great ammounts of research, I am pretty certain that I have a loadomatic type distributor. These have only vacuum advance and you can see the springs mounted on top of the plate in the dizzy. The apparently work with a vacuum that is a mixture of ported vacuum and venturi vacuum, the mix of which is based on the spark control valve. PLEASE CORRECT ME IF I AM WRONG

My reading (Ford shop manual, internet, forums) indiactes that in 65 the 240 had the loadomatic carb and dizzy setup, but the 300 did not. The 300 had a mechanical advance as well as the vacuum and the carb did not have a spark advance valve. According to what I have read, the loadomatic setup was phased out pretty quickly in the 240 and NEVER was used in the 300.

Based on that info, I have set out to buy a dizzy for a 300, which should work fine on my engine. Especially since someone swapped out the autolite 1100 along the way for a newer unit without the spark control valve. I looked up and ordered a dizzy for a 67 300 engine from autozone. NAPA and Rockauto listed the same 2609 part number.

But what arrives? A dizzy INDENTICAL to my old one. No mech advance, and springs above the plate, consistent with loadomatic setup.

There are only three points type dizzys listed. the 2609 seems to be a loadomatic unit, The later (early seventies) unit 2689 has dual vacuum hooks. The 2610 units start showing up in the late 60's, and are listed as THERMACTOR dizzies.

BUT, I have no thermactor, and neither did the 300 I6 in 65. And from what I can garner, the thermactor did NOT interact with the distributor. Can anyone comment? Was there something special about the thermactor that made the dizzy different, or is this just the way that the parts places are designating the difference. It is interesting that the vehicles with thermactor pumps do have the later mechanical/vacuum advance dizzies.

I got a seemingly knowlegeable fellow on the phone at Autozone. When I asked him how it could be that NAPA, Rockauto, all have the same thing, he noted that FORD supplies the basic information to all of them. He was NOT suprised that there might be an error in that old a setup.

So, very specifically -- is a thermactor dizzy somehow special and only for thermactor equiped motors? And, if you know, does the absence of a spark control valve clearly mean that I do NOT have a loadomatic dizzy.

Thanks

cdherman

 

CDHerman:
I goofed. I misread your description of your distributor.
If you read my original post, please disregard!

 

I think I would order the dizzy for the thermactor motor and see what you get.

 

In the meantime, I did order the "thermactor" unit. It is indeed the dual (vacuum/mechanical) advance, single vacuum hookup unit.

Apparently,since the loadomatic units were phased out at the same time that thermactor emessions units started being used, the "thermactor" dizzy designation occured. So far as I know, the thermactor unit has NOTHING to do with the dizzy.

later....