05-21-2017, 06:12 PM
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#1 |
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Senior Member
Join Date: Jan 2012
Location: New Jersey
Posts: 1,426
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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 |
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05-21-2017, 06:46 PM
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#2 |
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Member Emeritus
Join Date: Nov 2012
Location: Wichita KS
Posts: 16,132
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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.
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05-22-2017, 12:28 AM
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#3 |
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Senior Member
Join Date: Apr 2015
Location: Sweden
Posts: 3,045
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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. Last edited by flatheadmurre; 05-22-2017 at 04:57 AM. |
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05-22-2017, 01:53 AM
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#4 |
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Member
Join Date: Sep 2010
Location: Menifee, CA
Posts: 61
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Re: Vacuum signal
...
Last edited by Kruzn40; 05-22-2017 at 02:17 AM. |
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05-22-2017, 02:06 AM
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#5 |
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Senior Member
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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... Last edited by flatheadmurre; 05-22-2017 at 04:57 AM. |
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05-22-2017, 02:16 AM
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#6 |
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Member
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Location: Menifee, CA
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Re: Vacuum signal
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05-22-2017, 04:33 AM
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#7 | ||
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Location: East Hartford, Ct
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Re: Vacuum signal
Quote:
Quote:
__________________
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05-22-2017, 04:54 AM
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#8 |
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Senior Member
Join Date: May 2010
Location: Manawatu, New Zealand
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Re: Vacuum signal
Ja vhat is VOT?
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05-22-2017, 04:56 AM
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#9 |
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Senior Member
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Location: Sweden
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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... |
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05-22-2017, 06:28 AM
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#10 |
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Senior Member
Join Date: May 2010
Location: Auburn, MA
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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?
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05-22-2017, 07:44 AM
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#11 |
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Senior Member
Join Date: Apr 2015
Location: Sweden
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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. |
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05-22-2017, 10:32 AM
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#12 |
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Senior Member
Join Date: May 2010
Location: SPEEDWAY INDIANA
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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.................... |
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05-22-2017, 05:37 PM
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#13 |
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Senior Member
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Location: New Jersey
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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.
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05-22-2017, 05:42 PM
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#14 |
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Member Emeritus
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Location: Wichita KS
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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. |
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05-22-2017, 05:50 PM
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#15 | |
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Senior Member
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Re: Vacuum signal
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05-22-2017, 06:07 PM
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#16 | |
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Member Emeritus
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Re: Vacuum signal
Quote:
I did 
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05-22-2017, 07:02 PM
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#17 | |
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Re: Vacuum signal
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05-22-2017, 08:54 PM
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#18 | |
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Re: Vacuum signal
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05-22-2017, 10:18 PM
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#19 |
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Senior Member
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Location: Orland Park,IL
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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.
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05-23-2017, 04:25 AM
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#20 |
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Senior Member
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Location: New Jersey
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Re: Vacuum signal
Fordors I use the car for around town and some highway runs. It's a stock 59L motor.
Thanks |
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