42-48 Crab distributor

[Sid]

In the process of pulling my Stromburg E fire dist. of and installing a stock style crab dist. I need to use an adaptor because my timing cover is a 3 bolt style. Question is where does the distributor get it's vacuum? Does it use straight manifold vacuum? No vacuum ports on my 97's

[cas3]

If you buy the adapter plate from speedway it has a vacuum port on it . Also note that most times the square boss that the vacuum port is in needs some filing to fit so the adapter sits flush. I forget what it hits, but check the fit when you get it and you will see. Good idea to ditch the modern thing and install a real dizzy

[cas3]

Reviewing, I did not answer the whole question. The stock manifold would have a vacuum port near the front for the dizzy. You mention "97's" , so I assume not stock, but still should have a vacuum port somewhere. The crab dizzy is a vacuum brake , not for spark retard as in modern gizmo's. I've not done it, but I read some folks lock them down to be turned off basically, as the modern gas and generally low by modern standards compression does not care. They have internal mechanical advance . I'll stop there, lets hear from some ignition experts lest I spew more incorrect information

[Tinker]

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Well to look at how it worked. It worked off the intake manifold. Holley entered the market in 39. Don't think holley carb based vacuum was till 8ba's. I could be wrong.


Now the concept of running them all the way out has some history and merit with today's gas. Being octane in the 40's was about 70. Hard to set ping. I run a slight drag.

I'd refer to the experts like bubba. Probably a slight drag. If your leather is gone. I have a few discs made a decade ago. Made by KenCt. Ya I don't want to start that, love/hate for me. Ken doinked me with a trade 97 for a chandler-groves script. Had no float and gas shot everywhere.