Vacuum advance

The vacuum advance on my 47 KB1 was not moving. I set #1 to tdc on the compression stroke and the notch on the pulley was aligned to the indicator on the front of the engine. Removed the vacuum line to the actuator. Removed the bolt underneath the distributer, which holds the distributer down, tapped the distributer clockwise to loosen it up and pulled it out. The shoulder bolt that attaches the vacuum actuator to the distributer was froze up. Removed the shoulder bolt and cleaned up with a wire wheel on a dremel tool. Removed the 2 nuts holding the actuator on and was able to clean the back side, atmospheric air side, of the diaphragm. Got a nice sized pile of dirt. Squeezed in on the diaphragm and placed my finger over the port, it held the vacuum. Next, I slid the numbered plate, indicater (pointer) and timing lock down plate (after loosening) off the shaft of the distributor. Prior, I had placed a mark on the lock down ring and distributor to maintain the current timing. Cleaned everything up and started to assemble. The bolt that holds the distributor down is a shoulder bolt. Also, starting from the head of the bolt, there is a spring, a large flat washer and then a small washer, about the same diameter of the shoulder. The bolt goes through all three plates. The large washer backed by the spring holds the lock down ring plate through a non-slotted hole, the shoulder portion goes through the pointer's non-slotted hole and then the small washer at the end of the shoulder goes through a slotted hole in the numbered plate. After installing the distributor, it fired right up. Before it would labor while trying to start. Had to turn the idle down as well. Now for a question. What exactly is the number plate and indicater used for? To me, it appears that it is to set the amount of vacuum advance. The pointer plate can not move, it is attached to the shaft and has a bolt going through a non-slotted hole. But the number plate can be adjusted with it's slotted hole. If you move the number plate, it will adjust the amount of throw the vacuum actuator will have, thus the amount of vacuum timing. ??

No one wants to get their head cut off...
Here goes!
The POINTER and THE SCALE are to do minute INITIAL timing adjustments. Timing lights weren't in everyone's toolbox seventy years ago...
LOTS of old cars have a similiar scale. If it checks amount of vacuum advance too, great!
The fact that you can clean things up and make vacuum advance work is amazing. Good old stuff!

Ok..maybe this will help or not but it is my 2 cents. When I got my KB1 there was no advance working and I found that the distributor was not moving. It started hard and was very hesitant while accelerating.

What I did in this order: dissasembly of carb ..clean and re-install, replaced plugs, plug wires, points,and set the timing with the mark on the front pully by loosening the the screw behind the distributor that locked it to the shaft, cleaned and lubed distributor plates and bolts.It still hesitated. Still no advance so further investigation found that the hold down bolt under the distributor housing had a wide washer locking it in place. I removed the washer and found a small profile lock washer that allowed the lock down bolt to fit INSIDE the slot in the lower plate.. This allowed the bolt to lock the distributor in place but still let the distributor move for advancement .

I then advanced the initial timing a smigeon and played with carburetor adjustment. Starts well, no hesitation after warm up.

Don't know if any of this will help but I guess it can't hurt. Good luck .

BK

^^^^yup^^^^ has to be assembled correctly with correct parts, EZ to drop on ground and go get a washer that kind of looks like the old one out of the bucket of spare bolts,

the timing marks are as said to fine adjust, set distributor to TDC with pointer at zero using side clamp to tighten, then you should be able to move distributor body the throw of vac advance, you twist the steel vac line and mount to fine tune, tighten with set screw, if assembled right distributor should still be able to advance, if it is clamped down tight, something is missing or on wrong,

Working on understanding this distributor and the advance system. It's a bit different.

I believe there are some errors in the above explanations?

The bottom plate which has the timing marks on it does NOT have a small washer that fits inside the cutout. That cut out is to give you enough room to go +10 to -10 degrees to set the initial timing. This plate does NOT move when the engine is running or when the vacuum advance moves. That cut out is ONLY used when setting the initial timing and then is locked down tight. It must be stationary or the vacuum advance has nothing solid to pull against to rotate the distributor when the engine is running.There is a washer underneath this plate that goes against the engine block to lock it down.
This picture will help;



The shop manual has a confusing diagram of how the step bolt and spring assembly goes together. Here is the step bolt and spring that go thru the vacuum advance plate and still allow it to rotate. You can see the witness marks on the plate from the spring loaded washer. The three nubs on the plate go against the bottom of the distributor body to help provide "bite" so when the plate rotates it pulls the distributor with it.



As was posted above the spring loaded washer allows the vacuum advance plate to rotate while holding the other two plates stationary. One thing I have NOT seen mentioned is I think you need to lubricate between the plates so they will rotate?

The pointer is the only plate of the three that does not have a slotted hole where the spring bolt goes thru it. That's because the shoulder of the step bolt clamps the pointer plate and the timing plate tightly to the block.



The distributor has a large oil cap. What is it lubricated with?
Just engine oil? Was packed with thick muck when I took it apart.


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it's a grease cup, you put in grease from your grease gun, turn it every couple hundred miles or so, forget the exact, manual states it in

you are miss reading what was posted, the stepped washer goes in the elongated hole just like your photo shows, only you have it up side down in the picture (or it is an optical illusion in the photo), outer rim should be upward not down toward the clamp plate surface,

Fwiw, this is how mine was and still is now. Except for a new spring. Vacuum canister operates distributor correctly. I did set some advance with the distributor shaft clamp bolt. Then used the advanced/retard adjustment to tweak it.

Diagram showing washer.

yes, but correct position is stepped washer raised section fits down into wide opening of clamp plate,

the purpose is to hold down the clamp plate while not interfering with free movement from advance unit,

having it upside down makes it have contact with clamp plate putting resistance of free movement,
and kind of defeats purpose of having the stepped section of it? no?

oh, and the step also serves to center the spring on the washer,

but if it works for you I don't care if you prefer it to be installed upside down or not, on my trucks I install it right side up,

Glad to hear which way that stepped washer goes! Large end of the spring fits in the bowl of the washer. Got it.

I have assembled it both ways now and it seems to work in either position but I was sure IHC stepped the washer for a reason.
That picture from the parts manual was confusing too because I could not tell which position the factory wanted it installed?

Turns out my big problem was getting the step bolt properly centered so it ONLY clamped the pointer and timing plate solid and NOT the vacuum advance plate. I think what was happening was the cupped washer kept getting caught under the shoulder of the bolt. This clamped all 3 plates solidly together so nothing could move when the bolt was tightened. The stepped bolt must NOT clamp or trap the cupped washer. You will see that when it's apart. The hole in the washer is large enough for the stepped section of the bolt to pass.The washer must be free to move up and down on the stepped section of the bolt. The spring holds the washer against the vacuum advance plate but not so tight it can't move when the vacuum pot pulls on it.

Two or three times doing it helped too but it was frustrating until I got it assembled right and the distributor would still move with the vacuum advance.

Now it finally does make sense!
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