Vacuum signal
 

On a blown motor, where should I get the vacuum signal for the distributor? I keep hearing conflicting reports of getting it from the carb as oppssed to the intake, but I would like to hear from the Flathead guys!
Thanks,
Joe

Re: Vacuum signal
 

I've never ran a blower, but if you connect the vacuum line to a pressurized intake you are not going to get a vacuum.

Re: Vacuum signal
 

When the carb is closed the blower isn´t getting air so you get nothing to push in....
So vacuum connection at manifold.
Hooking it up to the carb you can get vacuum advance at WOT.

Re: Vacuum signal
 

...

Re: Vacuum signal
 

If you take the vacuumsignal between blower and carb you can get vacuum advance at WOT...
Vacuum should be taken at manifold and reflect what happens there...no matter how you are feeding the engine.
If there was a positive pressure feed at all times you would have a runaway engine never idling...

Re: Vacuum signal
 

...

Re: Vacuum signal
 

For me and some of the rest of us who don't understand what may or may not be 'tweet-speak', what is VOT?

Re: Vacuum signal
 

Ja vhat is VOT?

Re: Vacuum signal
 

Sorry...should have been WOT(wide open throttle).
I apologize for being lazy not writing it in full and on top of that louzy at spelling...

Re: Vacuum signal
 

First things first. What kind of distributor are you running? The next thing is has it been set up for this blower? I do not know enough to answer the questions but I do know that running a blower may require a different advance curve than a stock motor. Also what kind of carb are you running and are there any modifications to it?

Re: Vacuum signal
 

Going for boostretard with a conventional distributor takes totally different setup.
Depends on how much boost you have and if detonation/knocking will be an issue.
On a street flathead with a mild boost you should get away without it...or hide an electronic module taking care of the advance for you.

Re: Vacuum signal
 

Wow , wide range of answers.
The answer depends on what distributor are you trying to run...?????? A picture would help.

Best advise is forget vacuum advance on a blown engine, tune the ignition to run with the blower boost etc and drive it !!!!!!! A blown spark advance would differ a lot from a non blower engine....................

Re: Vacuum signal
 

Sorry, It's a Chevy set up by a Barner. It was set up for a blower. Advance is 24 degrees at 2800 rpm.

Re: Vacuum signal
 

There is an interesting thread on the HAMB on this topic.

https://www.jalopyjournal.com/forum/...vacuum.412468/

I'm with Bubba, I have run full mechanical advance on several engines with very good success.

Re: Vacuum signal
 

Can you post a link please?

Re: Vacuum signal
 

I did :)

Re: Vacuum signal
 

Sorry! Got it! Read the whole thing & now I'm totally confused!!!

Re: Vacuum signal
 

That was sort of my conclusion as well. As I aready stated I have run a lot of mechanical only ignitions and was very satisfied with the results.

Re: Vacuum signal
 

I run an off topic blown engine and have vacuum advance on it connected to the manifold. My combination has a relatively mild cam, a 6-71 @ 15% under with two 600 Holleys running direct linkage. Boost is 6 pounds maximum but that is when you open the carbs, when cruising down the road it always is in vacuum and for that reason I decided to run vacuum advance. Connected to the manifold it will only provide the extra advance when you need it, if you give it enough throttle to go into boost the vacuum canister will immediately retard your timing to the maximum of your mechanical advance.
I guess it all depends how you intend to drive, will it be a highway car or just a local cruiser? Any car should be a total, thought out combination for what you want out of it.

Re: Vacuum signal
 

Fordors I use the car for around town and some highway runs. It's a stock 59L motor.
Thanks