All Small Six Did You Convert a Spark Control 1100 Carburetor to ported vacuum?

[Alkraut]

I read the interesting and informative posts on converting the carburetor conversion from spark control vac to ported vac. This facilitates the use of a distributor having vac and centrifugal advance, and uses “ported” vacuum from the carb. This replaces the stock Load O Matic distributor.

For those who completed the conversion of the Autolite 1100 SCV to ported vacuum using the "JimG : Convert "Spark Control" 1100 to ported vacuum?" method, what were the results?
Did plugging the three specified ports with setscrews provide the desired results? Were other carb modifications required? Distributor issues? Engine idle OK? Hesitation or flat spots? Any tips and info on performing this job are appreciated. Thanks.

 

[powerband]

always interested in carb and carb-mod discussions,
.
"This facilitates the use of a distributor having vac and centrifugal advance ... "
..
... isn't first issue whether an early LOM system distributor can be replaced with a distributor with vacuum and centrifugal?. Not many options for early engines with smaller oil pump drive and different block bore for distributor .

Do any Later OEM points/cdsr' distribs with both advances fit LOM factory engines ?.
.
( later non-LOM points/cdsr distribs will swap with later DSII distribs for electronic ign )

.
hav e fun

 

[powerband]

from the wayback machine new to me:
.

...question is what year is your block casting?
If the block casting is a C4, or '64, a DS II will not be an easy upgrade, because of the hole size and (oil pump) drive shaft differences ...
If your '65 is a later casting, either C5 or C6, the later distributor should be a direct swap-in.
Check out your block casting #.
.
... so now I suppose any later Vac and centrifugal advance dizzy- including points/cdsr AND DSI and DSII should fit C5xx (65) and later blocks -- .

have fun
.
.

 

[Alkraut]

The 1965-67 200 six will accept the centrifugal/vacuum distributor that was used in the “thermactor” engines. Should also fit the 170 engine. the shape/size and oil pump drive is the same as for a Load-o- Matic. The Cardone remanufactured 30-2613 is an example. It has both mechanical and ”single port” vacuum advance. Used with a non-SCV carb that has a "ported" carb Vac source.

 

[Frank]

The 1965-67 200 six will accept the centrifugal/vacuum distributor that was used in the “thermactor” engines. Should also fit the 170 engine. the shape/size and oil pump drive is the same as for a Load-o- Matic. The Cardone remanufactured 30-2613 is an example. It has both mechanical and ”single port” vacuum advance. Used with a non-SCV carb that has a "ported" carb Vac source.
View attachment 19640

I can not assist with the LOM carb mods. However if it can be modified to supply ported vacuum, this distributor will work well, and is a step up from stock. . A couple of guys have merely plugged the carb ports and used manifold vacuum to the distributor. Not ideal, timing will be way too advanced at idle.

 

[wsa111]

Delete SCV on 1100 Autolite for Ported Vacuum

Here are the instructions to delete the SCV on a Autolite 1100 & convert the vacuum port to ported vacuum. You need a #36 drill bit to drill a shallow hole to just the depth of the 6-32" brass set screw. You will use 3 of these set screws. Tap only the orifices circled in red there are three...

fordsix.com

 

[wsa111]

Delete SCV on 1100 Autolite for Ported Vacuum

Here are the instructions to delete the SCV on a Autolite 1100 & convert the vacuum port to ported vacuum. You need a #36 drill bit to drill a shallow hole to just the depth of the 6-32" brass set screw. You will use 3 of these set screws. Tap only the orifices circled in red there are three...

fordsix.com

If you want it done my charge is $95.00 plus parts & shipping. contact me at amblerrace@live.com Bill wsa111

 

[Alkraut]

Delete SCV on 1100 Autolite for Ported Vacuum

Here are the instructions to delete the SCV on a Autolite 1100 & convert the vacuum port to ported vacuum. You need a #36 drill bit to drill a shallow hole to just the depth of the 6-32" brass set screw. You will use 3 of these set screws. Tap only the orifices circled in red there are three...

fordsix.com

After plugging of the three holes, does "residual" vacuum still reach the distributor at idle? If so, does will it result in vacuum advance? Or a vacuum leak?
I understand how the SCV carb turns on throttle vacuum for a Load O Matic distributor on non converted carburetors, but what "triggers" and turns on the ported vacuum on the converted 1100? Appreciate the info.

 

[Frank]

A carburetor's ported vacuum port is located inside the throttle bore just above the leading edge of the throttle. When the throttle is closed, no vacuum is present. As the throttle is opened and the edge of the blade approaches the port it exposes it to manifold vacuum. "Ported vacuum" in all carburetors (except the LOM) is intake manifold vacuum that is present on the vacuum advance unit at all times except idle. There is no "gradual"
vacuum. When the gas is pressed the distributor timing is snapped ahead, goes from 0" to full manifold vacuum instantly.
The LOM advance system is entirely unique, and it's vacuum advance function does not cross over or correlate to normal distributors.

 

[Alkraut]

Thank you Frank for the great explanation!
At idle, wouldn't the throttle plate be slightly open when the "idle speed" screw is adjusted? Therefore exposing the vacuum port and full manifold vacuum? Also when the auto choke sets the throttle higher.
So would this provide vacuum advance at idle? Is is best to set initial timing lower than the 12 deg BTDC my "66 auto trans is now at?

 

[Frank]

Thank you Frank for the great explanation!
At idle, wouldn't the throttle plate be slightly open when the "idle speed" screw is adjusted? Therefore exposing the vacuum port and full manifold vacuum? Also when the auto choke sets the throttle higher.
So would this provide vacuum advance at idle? Is is best to set initial timing lower than the 12 deg BTDC my "66 auto trans is now at?

Good questions, but don't overthink it. The placement of the vacuum port will not pull vacuum at base idle. Some carbs it will pull vacuum with the choke on, some require more throttle opening.
You don't want advance at idle, no vacuum to distributor for setting base timing.
Remember, all this is based on standard carb/ignition system, not LOM.

 

[Alkraut]

Good information Frank, thanks.
Would like to hear the results of members who performed the conversion.

 

[Frank]

Good information Frank, thanks.
Would like to hear the results of members who performed the conversion.

Mr. Ambler posted the procedure in post #6. It is a detailed procedure which requires internal carburetor mods, anything short of this will not provide correct function of vacuum control. If you are not comfortable and at least a bit practiced with carb teardown, his price of $75 is the best solution, and well worth the money.

 

[78_200_C4]

The LOM Autolite 1100 has a throttle bore vacuum advance port and a venturi vacuum advance port.
It does NOT have a ported vacuum advance port unless one is drilled above the (plugged) throttle bore vacuum port.
I have a LOM Autolite 1100 and LOM Holley that I converted to ported vacuum. Both have ported vacuum ports drilled above the throttle bore port.
There is a reason that Ford says to disconnect the vacuum advance line when setting the initial timing at idle. The reason is that the throttle bore port is providing vacuum to the vacuum advance at idle. Unless the throttle blade is near completely closed at a very slow idle the throttle bore vacuum port will advance the timing.
I have had a 200 idle slow enough to shut off the vacuum advance but any slight further movement of the throttle blade resulted in the advance kicking in which resulted in greatly increased idle speed. This was after I followed flawed "Convert to Ported" instructions.
If a person wants to run a centrifugal-vacuum advance distributor and does not mind using throttle bore vacuum advance plug the venturi port with expoxy or a Phillips head 6-32 screw. You will get the same results as following flawed "Convert to Ported Vacuum" instructions. Both ways will supply throttle bore vacuum to the vacuum advance.

 

[MustangDadDrake]

reviving this because it is interesting. I did do this conversion myself, not sure how correctly, but I did not notice much if any of a difference.

I did read a lot on the ported v manifold vacuum and when I ran manifold i was way too advanced for my liking and went back to ported.

 

[78_200_C4]

reviving this because it is interesting. I did do this conversion myself, not sure how correctly, but I did not notice much if any of a difference.

I did read a lot on the ported v manifold vacuum and when I ran manifold i was way too advanced for my liking and went back to ported.

The LOM Autolite 1100 doesn't have ported vacuum (unless a person plugs the throttle bore vacuum port then drills a ported vacuum port above it). The modification doesn't effect the throttle bore port which provides vacuum at idle to the LOM distributor. The modification does not create a ported vacuum port. The original "Drop a Load" article was and is wrong.
The real purpose of the modification should not be stated as "convert to ported vacuum."
The real purpose of the modification should be stated to "block the venturi vacuum" so the LOM carb can be used with a centrifugal-vacuum advance distributor. The venturi vacuum could over advance the total timing if used on a centrifugal-vacuum distributor causing pinging and detonation which can damage an engine. The real purpose to do the modification is not ported vacuum, but creating a lack of venturi vacuum.
The only modification needed to block the venturi port is to thread the port with a 6-62 tap then screw in a round head phillips 6-32 screw. This will block the venturi port but not the throttle bore port.