8BA vacuum advance question

cabot

cabot

Junior Member
I have a nice running 8BA in a 1941 Ford. The distributor vacuum advance is hooked up to the distributor but with no advance being actuated. The carb is a Ford script that looks like a holley 94 with a port near the back for what I think is vacuum, but this does not draw the advance. What is the best way to get the advance to work? Get an 8 BA carb? or hook it to another source ie split the wiper vacuum port?
Thanks for any help.
 
The rear port is for the vacume.This is the only vacume port to be used with the dist. You CANNOT use manifold vacume. Possibly your vac advance is stuck.They can be repaired i think. ken ct.
 
We have brand new ones in stock. The housings are crimped together so it would be rather difficult to open up and replace the diaphragm.

What Ken said is correct about the vacuum signal....from the rear port in the carb itself....not manifold vacuum.
 
I have disconnected the tube and sucked on the tube, it moves the distributor plate easily and the advance unit looks real good no rust, or crud. Is the loadomatic real picky on the exact amount of vacuum (the hole in my carb could be too small?) Could the little springs in the dist plate be hooked up wrong, I know there are two tensions.
That is very helpful to tell me the manifold is not the correct vacuum signal, thank you.
 
If the port is mid-body, it's the right carb. Put a vacuum gauge on the port. The vacuum should increase as the revs increase which is the opposite of what manifold vacuum does.

Sorry, I don't know what the readings should be.
 
The Load-A-Matic was designed by Holley to work with either the Holley 8BA carb for the Ford or the Holley 885 for the Mercury. The system will work correctly with either of these carbs. If you use and older carb you may have to talk to Bubba about a distributor to work with it. The Holley Load-A-Matic system is not the best in the world and the ignition can be improved upon by replacement of it with the right combinations of distributor & carburetor.
 
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cabot said:
I have disconnected the tube and sucked on the tube, it moves the distributor plate easily and the advance unit looks real good no rust, or crud. Is the loadomatic real picky on the exact amount of vacuum (the hole in my carb could be too small?) Could the little springs in the dist plate be hooked up wrong, I know there are two tensions.
That is very helpful to tell me the manifold is not the correct vacuum signal, thank you.
Click to expand...


The vacuum specs for that distriubtor is .5 to 3 inches of vacuum . The springs are large and small and the spring pins are eccentric so they can be turned for adjustment.
Adjustment ( even with a machine) is almost impossible as the vac range is so low. ie= .5 = 3. 1/2 degrees etc
 
Do NOT open up the hole in the venturi.Could it be blocked with crud. You can stick a wire through it from the fitting hole and should come out inside one of the venturies. Another possibilities you have the wrong base [cast iron part] from an earlier 94 which dosen't have the extra hole in the base for the vacume.Stick wire of approite size in all the 7 holes in the base section which should # 7 of them. ken ct.
 
the vacum will only be seen when the engine is throtaled open and has enough air flow through the carb to make vacume ..it is venturi vacum as the engine speeds up the advance comes in. with manifold vacume the distributer is vacume retarded until you open the throtle and loose the vacume that lets the ign advance ..you need to know what you have and how it works (load o matic venturi vacum advance) others (manafold vacume retard)I hope this helps...John
 
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The use if the Load a matic distributor, even in perfect working condition. Leaves allot to be desired, plus it doesn't work with engine modifications. Get a SBC conversion they work very well in a flathead. They can also be converted to 12v electronic.
 
Cabot,
I believe Kens 2nd post may be your problem. The iron base
on your carb must have 2 small passages on the right side....the larger
for the idle circuit and the smaller for the venturii vac for the dist.
Also check to make make sure the gasket between the base and bowl
has the 2nd hole in it to accomodate the above. All these little obscure
details can add up to head aches. Most basic 94 style carb parts can
be and are switched....even though they should not be.
Charlie ny
 
OL'Rons advice is rite on. I added one to my 8rt and what a improvement it made .I too highly recomend this ignition upgrade. Add 12v and MSD and its bullit proof.. the best money you will ever spend for a performance gain. Bubba ign's rule
 
I am blown away at the helpful suggestions and the new knowledge I've gained. I am set to make the stock distributor work (I am not into high performance) and now know many things to look for. I will keep you posted as I go.
Thank you all for teaching me the difference between bases, gaskets, and manifold vs. venturi vacuum.
 
Charlie ny said:
Cabot,
I believe Kens 2nd post may be your problem. The iron base
on your carb must have 2 small passages on the right side....the larger
for the idle circuit and the smaller for the venturii vac for the dist.
Also check to make make sure the gasket between the base and bowl
has the 2nd hole in it to accomodate the above. All these little obscure
details can add up to head aches. Most basic 94 style carb parts can
be and are switched....even though they should not be.
Charlie ny
Click to expand...
Those 2 bases cannot be switched around. They will fit but you lose the vacume port.lol ken ct.Details.details. :)
 
This is the final answer here in my case. It was the iron base being switched at some time before I had the carb in a rebuild. The iron base did not have the vacuum hole. So, I went to my carburetor drawer and found a parts 94. Can you believe it does not have the port mid section to run the advance but when I took it apart it had the vacuum opening in the iron base! Quick switch and it is smooth with an acting advance. This is why we buy "extra" parts at the swaps. Thank you everyone, especially ken and charlie, (now I know about the tiny seven secret holes).
 
Great thread. Helpful answers to the question and a good result for the poster, who luckily had extra parts on hand. Always nice to hear the final result, especially when its good.
 
cabot said:
This is the final answer here in my case. It was the iron base being switched at some time before I had the carb in a rebuild. The iron base did not have the vacuum hole. So, I went to my carburetor drawer and found a parts 94. Can you believe it does not have the port mid section to run the advance but when I took it apart it had the vacuum opening in the iron base! Quick switch and it is smooth with an acting advance. This is why we buy "extra" parts at the swaps. Thank you everyone, especially ken and charlie, (now I know about the tiny seven secret holes).
Click to expand...
Thanks Cabot,glad you found the problem always willing to help out from Charlie an myself and all the others who chimed in. ken ct.:)
 
cabot said:
This is the final answer here in my case. It was the iron base being switched at some time before I had the carb in a rebuild. The iron base did not have the vacuum hole. So, I went to my carburetor drawer and found a parts 94. Can you believe it does not have the port mid section to run the advance but when I took it apart it had the vacuum opening in the iron base! Quick switch and it is smooth with an acting advance. This is why we buy "extra" parts at the swaps. Thank you everyone, especially ken and charlie, (now I know about the tiny seven secret holes).
Click to expand...
LOL if you know they should be there its no secret the older ones have only 6 of them.
 
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