I have an automatic 68 C code coupe with wha was orig. a 2 bbl. 289 obviously, but i have since put a 4 bbl. manifold and carb on. Myproblem is the dizzy i have right now (stock) is a dual diaphragm unit that has two vacum lines, one that goes to the carb and the other that goes to the thermostat housing manifold vacum source. On the top of the thermostat housing there is the switch that has three vacum ports running off the tee, that i want to get rid of in place for one of those nice chrome units. So what im asking is, can i just simply slap a single diaphragm dizzy down in place of the stock dual diaphragm, and when i do this i should be able to put a regular early style thermostat housing down in place of the stock one with the switch n all that on top right?? ANy help would be greatly appreciated. Also, anybody got a distributor they want to get rid of??

 

just buy the single diaphram for the dist should just swap out and you can eliminate the vaccum ports on the thermostat housing by using one without them

 

i dont know if all the vacuum advances are adjustable, but i know msd and accel or mr gasket makes adjustable units. they are only like 20 or 30 bucks, and will allow more fine tuning.

 

So i can replace the dual diaphragm piece with a single diaphrahm pieceand not have to pull or swap out the dizzy? CAn somebody reccomend a good vacum advace? But as far as how the dizzy is set up, by eliminating the dual diaph. advace and the thermostat vacum ports, the dizzy will still function the same right?

 

yes it will function the same, heres a crane model:

http://www.cranecams.com/?show=brows...Number=99607-1

it says 73-up, i dunno what the differences are but you get the idea - they can easily be replaced without having to remove the dizzy, you just pop the rotor off and the cover plate thats between the points and rotor. also, VERY highly recommended to grab a petronix conversion unit to replace those old points with.

 

The "switch" on the top of the thermostat housing that the vacuum lines are plugged into is a temperature sensor. If the car starts to run hot, and the sensor is working properly, the vacuum advance is adjusted and timing is retarded. One of the lines goes to manifold vacuum, one goes to timed vacuum and the last goes to the distributor. On single diaphragm distributors, I’ve been told that you can get rid of the switch and run a vacuum line straight from the timed vacuum port to the distributor. I’m not sure if that is the case with dual diaphragm distributors though.

 

go to your local checker shucks or kragen and get a replacent vaccum advance from them i know the one for my 67 was adjustable and it was only 12.99