All Small Six JimG : Convert "Spark Control" 1100 to ported vacuum? Sun Aug 21, 2011 6:24 am

[78_200_C4]

The Ford Falcon News
JimG Sun Aug 28, 2011
I'll post pictures as soon as I can take them. Basically though, I blocked the two passages that terminate in the Spark Control valve cavity, and the one behind the Distributor Vacuum outlet on the passenger side of the carb (the horizontal passage that goes into the venturi). I did this by drilling a shallow hole into the end of the existing passage with a #35 drill, tapping it to 6-32, and screwing a 6-32 X 1/8 brass set screw into the end of the passage, thereby blocking it.

JimG Aug 28, 2011
OK, as promised, I got the pictures taken today.
First, some background for those who've forgotten this stuff. Ported vacuum isn't rocket science. You just create an orfice in the venturi just above the throttle plate. You then create the necessary passages to connect the orfice to an outlet fitting.
Our Spark Control 1100s already have this. The problem is, it has some "extra" passages that must be blocked if we want ported vacuum.


JimG Aug 28, 2011
"Here is a photo I took that illustrates where all the passages go. The yellow part is the path we need for ported vacuum to work. The red paths must be blocked."


JimG Aug 28, 2011
DISCLAIMER: I've done this modification exaclty once, so I don't claim to be an expert. Your carb might be different than mine. All I can say is this: I made this modification, and it worked on my carb. Double-check your carb before you attempt this. Something might be different. Caveat Emptor!

JimG Aug 28, 2011
Next, the passage that connects to the rear of the spark control cavity.
If you think you'll ever want to return the carb to its previous "spark control" configuration, this is important. Otherwise, you can skip it. Measure the orfice in the brass insert shown. I used numbered drill bits and incorporated the go/no go method. The orfice in my carb was .032. Write this measurement down somewhere and keep it safe.

JimG Aug 28, 2011
Drill out the orfice and drill a shallow hole with a #36 drill bit. Tap to 6-32. Insert set screw as shown.
If you ever want to return the carb to Spark Control, just drill a hole in the set screw that's the same diameter as original orfice (in my case, .032"). This is where brass set screws are nice; they drill out so easily.
In this photo, the path for your ported vacuum is the center port, across the "trench" in the main body, and out the port near the bottom of the photo.

JimG Aug 28, 2011
One more port to block. Remove any brass fitting on the Load-O-Matic outlet on the passenger side of the carb. You'll be drilling, again, with a #36 bit straight into the Load-O-Matic outlet, blocking the port shown by the paperclip in this photo. Again, drill a shallow hole, tap to 6-32, and insert a set screw.
Unfortunately, I couldn't get a good shot of the set screw inside the Load-O-Hole, but I think you get the idea from looking at the previous photos.

Below is what I did when my 1100 had vacuum to the vacuum advance unit at idle after the JimG modifications.
There is a brass plug on the side of 1100 that can be removed to drill a new throttle bore vacuum port above the old one. JB Weld can be used to plug the old port. The plugged port is marked in blue You just need the port high enough to not have vacuum at idle. The new port could be lower than the one that I drilled.
I used a 6-32 Phillips head screw to block the venturi port instead of a plug that might fall into the carb.

Danville, Virginia, JimG's Falcon Sun Aug 28, 2011
Here's a shot of The Bird with the wideband sensor at the tailpipe.

 

[Frank]

The distance of the drilled ported vacuum supply hole from the upper edge of the throttle blade will determine how quickly vacuum advance occurs when cracking open the throttle. A few thousands of an inch make a difference that will affect very light throttle low speed cruising. The closer to the throttle, the sooner and sharper the timing will advance. The smaller the hole, the sharper (more quickly) the timing will fully advance. A larger hole spreads full advance out over a few more degrees of throttle opening.
All of this is relative to the first few degrees of off-idle throttle, and does make a difference.

 

[78_200_C4]

I found out that the distance from the throttle plate matters by drilling a spark valve Holley vacuum advance port. It didn't have a brass plug to remove to drill the new port. I had to drill it going in the throttle bore at an angle and it ended up higher than I wanted it. On the 1100 looking inside where you want to drill the new port you can't see where the original port is. I believe I drilled the new port at the top of when I should have drilled it at the bottom.
A non Load'O'matic distributor without the vacuum advance connected should out perform a Load'O'Matic. The 1100 venturi port (vacuum leak) could be plugged along with the vacuum advance port.
If someone doesn't want to drill a new vacuum port they could just plug the venturi port. The spark valve will still provide throttle bore vacuum. The venturi port would no longer provide too much advance at lower manifold vacuum on a non load'O'Matic distributor.

 

[Frank]

I found out that the distance from the throttle plate matters by drilling a spark valve Holley vacuum advance port. It didn't have a brass plug to remove to drill the new port. I had to drill it going in the throttle bore at an angle and it ended up higher than I wanted it. On the 1100 looking inside where you want to drill the new port you can't see where the original port is. I believe I drilled the new port at the top of when I should have drilled it at the bottom.
A non Load'O'matic distributor without the vacuum advance connected should out perform a Load'O'Matic. The 1100 venturi port (vacuum leak) could be plugged along with the vacuum advance port.
If someone doesn't want to drill a new vacuum port they could just plug the venturi port. The spark valve will still provide throttle bore vacuum. The venturi port would no longer provide too much advance at lower manifold vacuum on a non load'O'Matic distributor.

I was able to post the above due to a port location problem with a china YF carb. What I posted is totally obvious, not science, but is something I'd never thought about until this carb (now in service). The vacuum advance ported hole was machined roughly 20 thousandths higher than a "real" YF. That truck is geared hi, 303 trans, and most commuting is @ 35 on flat streets. Was getting no vacuum advance, and was a dog. There was no way to get a drill bit in there, so solved the problem by cutting a thin slot in the throttle blade in line with the port. Width of a thin hacksaw blade, no more than 20 thou deep. The air channeling past the slot is enough to activate the advance at the critical first few * off idle, but not enough to pull at curb idle.

 

[78_200_C4]

I was able to post the above due to a port location problem with a china YF carb. What I posted is totally obvious, not science, but is something I'd never thought about until this carb (now in service). The vacuum advance ported hole was machined roughly 20 thousandths higher than a "real" YF. That truck is geared hi, 303 trans, and most commuting is @ 35 on flat streets. Was getting no vacuum advance, and was a dog. There was no way to get a drill bit in there, so solved the problem by cutting a thin slot in the throttle blade in line with the port. Width of a thin hacksaw blade, no more than 20 thou deep. The air channeling past the slot is enough to activate the advance at the critical first few * off idle, but not enough to pull at curb idle

My concerns were improving the performance of non centrifical advance Load'O'Matic carbs and distributor equipped vehicles. The ability to install a distributor with centrifugal advance even without vacuum advance would provide improved performance over the Load'O'Matic. I have ran Ford dual point and Mallory distributors without vacuum advance. My Fords were not dogs without ported vacuum. Plugging the vacuum adavnce port on a Load'O'Matic 1100 and running a centrifugal adavnce only distributor would be a performance improvement. Most people have few tools and less practical experience. They need a simple uncomplicated performance solution after they buy a Load'O'matic small six powered Ford. They could always run manifold vacuum advance which could be adjusted.

 

[bubba22349]

Thank you very much 78_200_C4, those pictures are so much better as well as the instructions I have converted this thread into a Sticky too. I have run into problem's more than once trying to explain this to some people about how to do it. The pictures help to because you can really see better which of those ports too plug since at my age I need all help I can get to see some of the smaller thing's!