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Question about Autolite 4100 Carb

 
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Old 05-15-2019, 10:41 AM
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Question about Autolite 4100 Carb

In the picture below of a Ford 4100 4bbl carb one tube connection is caped and it was for a heat tube for the choke, I will not need to use it as I am going to convert to manual or electric choke. Can I cap the other connection that is in the picture as I don't think I need it?

In this picture below it shows a vacuum connection from the carb base, can this be connected to the distributor vacuum advance connection?
 
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Old 05-15-2019, 11:23 AM
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Yes, you want to cap the fitting in the air horn since if left uncapped, unfiltered air would enter the engine.
The port in the baseplate can be used for the distributor advance if it is ported, not manifold vacuum.
 
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Old 05-15-2019, 11:46 AM
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mrpotatohead -- Thanks for the reply. How will I know if the connection in the carb base is "Ported or manifold vacuum?
 
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Old 05-15-2019, 11:54 AM
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Originally Posted by old28 View Post
mrpotatohead -- Thanks for the reply. How will I know if the connection in the carb base is "Ported or manifold vacuum?
Easy at idle it won't have vacuum at the port.
 
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Old 05-15-2019, 02:09 PM
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This is a new rebuilt motor on a run stand. just trying to get ever thing hooked up. Will it matter port or manifold vacuum if I have a HEI distributor? No smog or EGR valves (pre smog in CA).
 
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Old 05-15-2019, 02:45 PM
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Originally Posted by old28 View Post
This is a new rebuilt motor on a run stand. just trying to get ever thing hooked up. Will it matter port or manifold vacuum if I have a HEI distributor? No smog or EGR valves (pre smog in CA).
I prefer timed vacuum. That is how Ford designed it, and I run a lot of base timing and prefer not to have the timing further advanced while cranking.
 
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Old 05-15-2019, 03:52 PM
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On every 4100 Ford carb I've ever owner, that has been the vacuum advance port.
 
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Old 05-15-2019, 04:14 PM
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Jon Richards ---- What timed vacuum? I'm old school were vacuum is vacuum!
I set my timing with 12 base & 36 degree 3200 rpm on. This is a 300 inline 6 motor.

yardbird --- Ya I'm very old school where vacuum is vacuum! I think that connection on the carb base is a straight run to the intake inlet and is no different than hooking up to my inlets on the intake in this picture.
 
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Old 05-15-2019, 04:42 PM
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Originally Posted by old28 View Post
Jon Richards ---- What timed vacuum? I'm old school were vacuum is vacuum!
I set my timing with 12 base & 36 degree 3200 rpm on. This is a 300 inline 6 motor.

yardbird --- Ya I'm very old school where vacuum is vacuum! I think that connection on the carb base is a straight run to the intake inlet and is no different than hooking up to my inlets on the intake in this picture.
It is practically the same as manifold vacuum with the difference being that the signal is cut off when the throttle is closed.

I run 16* base timing, 36* total at 2300rpm on a 302.
 
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Old 05-15-2019, 04:44 PM
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Originally Posted by old28 View Post
Jon Richards ---- What timed vacuum? I'm old school were vacuum is vacuum!
I set my timing with 12 base & 36 degree 3200 rpm on. This is a 300 inline 6 motor.

yardbird --- Ya I'm very old school where vacuum is vacuum! I think that connection on the carb base is a straight run to the intake inlet and is no different than hooking up to my inlets on the intake in this picture.
The port on the 4100 is above the butterfly and is ported vacuum not manifold vacuum. Vacuum advance is old school, it also needs ported not full manifold vacuum.
 
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Old 05-15-2019, 05:52 PM
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You could be right. I know there is a ported vacuum on that side of the carb somewhere. I've checked them too many times with a gauge to make sure the port wasn't clogged up.
 
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Old 05-15-2019, 10:39 PM
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Thanks guys, I will use that port connection for my vacuum advance.
 
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Old 05-16-2019, 01:42 AM
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I can't wait to see that carb run that 6 cyl. That should have Plenty of gas mixture to put down that intake.
 

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