Hey, I am in the market for a new dizzy and am wanting to know your opinions on mechanical vs vacuum dizzy's, This will be going on a 351w engine with a 2barrel carb. I would also like to know the differences (besides one being vacuum & one being mechanical)

thanks!

 

I have an MSD pro billet mechanical distributor on my mach I. Pros are it fully adjustable you can adjust the advance curve just about any way possible in just a few minutes. No vacum lines to worry about of course makes it look cleaner. Con is it is huge while its good from a performance stand point that its bigger (better separation ) Its so big I think it takes away from the looks of my engine. Its so big it gets in the way of big air cleaners I had to get a smaller air cleaner.
If I were to do it over again I'd get a stock newer electronic one and go that way. Dont really like the looks of the MSD although it performs very well..

 

If the only difference is the additional vacuum advance, get it. The vacuum dist still has to have a mechanical advance, and vacuum is needed on vehicles for proper throttle response. I'd only put a non-vac dist on stationary equipment.

But a modern electronic dist will be vastly superior to any mechanical dist, in every way.

 

What do you think about this dizzy? It is from Professional Products and features a adjustable **** on the side so you can advance or retard initial timing by 1/2 degree increments. It is also a "ready to run" type of dizzy so i will not need a ignition box.

Here is the link.
http://www.summitracing.com/parts/PF...2/?image=large

 

Not true the vacuum is not needed my MSD work great. It advances with centrifical force. From a performance stand point you wont find a better distributor. Its just ugly.

 

I heard Vacuum advance dizzy's can improve MPG's and since this will be my daily driver one day the increased MPG's sound great, Performance would be nice but money is really tight these days so i can't afford much ATM, that is why i posted to link to Professional Products dizzy.

 

A vacuum advance will give you better mileage and instantaneous throttle response because it can vary timing with load and throttle opening in addition to engine rpm's.

 

I'd suggest a vacuum stock unit for yer truck. Just make sure it is a single vacuum line unit and not a dual. The one pictured is a single but there were dual units made for the era of yer truck. Unless you have emissions testing there, you don't need a dual line set up. You should be able to find one cheap. Just check it for lots of play by grabbing the shaft that the rotor goes on and rattle it back and forth. There will be some play but if it rattles around like a BB in a beer can, pass on it and find another one. You should be able to come across one for about $50.00.

 

Yes, vacuum advance is absolutely necessary for throttle response. Period."Great" isn't "as good as can possibly be". If you added vac.adv. to your dist, the engine would work BETTER than 'great', and it would respond to the throttle. Right now, it only responds to changes in engine speed, which can't change as quickly as you can stomp the pedal to the floor. All vacuum distributors ALSO have mechanical (centrifugal) advance.Yes, a stock electronic distributor performs better. With fewer moving parts & no adjustments to be made, they're more accurate, reliable, durable, & they produce more driveable power. However good your current non-vac dist is right now, it could be BETTER with vac. And neither compares to an electronic dist, which sucks compared to distributorless ignition, which is inferior to COP ignition.The performance is the REASON for the economy. A dist that makes better power at a given throttle position allows you to use less throttle (gas) to make the same power, which is the definition of efficiency.Ezzzackly!

 

whatever.

 

Thanks for all the responses, I will most likely be going vacuum on the dizzy!

 

I'm a sucker for intellectual arguments - you've convinced me now! Forget everything I said before...

 

Waste of time. I can only site my experiance with the distributor I have (and the old points distributor it replaced) it works great. Never used a vacuum one so I cant compare from a personal stand point. I did research what was best before I bought it and the Cleveland pros all liked this one best. The Cleveland is differnt from the Windsor so I dont know maybe it works better on this engine. All I know is its way better then the points distributor it replaced. I also know there are a whole bunch of guys using them in there race cars. Beyond that you wont get an argument from me.