Attempt to Pay Back # 2

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spinman_1949

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So I decided to buy a new distributor and then proceeded to take it apart.

This is a follow up to the original post called Ping and the next being Attempt to pay back.

What I wanted to do is see if I could make a backyard mechanic version of a Sun distributor machine. This is real basic. Totally manual, but anyone can do it.

Now the second portion of this process was to make the mechanical advance on the distributor adjustable. I thought about welding and doing the JB weld approach, but that is not what I would call adjustable. What I did is indeed adjustable. In fact it could almost be adjustable in the car, but pretty hard to line up the screws with the holes in the distributo that just happen to be in the exact right position to adjust. Screws? Yup Screws. 2 56 allen head screws to be exact. Oh and if you try this, make sure you have a good 2 axis vice and a knat tight quill on your drill press.

Frome here I will add pictures and try to add comments with each photo.


Well I am not sure how to add comments to each photo.

So I will add comments here


The first pictures show how I made a simple degree wheel. The straw has two lines 180 Degrees apart the length of the straw. Wife gets credit for the straw. Bottom line is this distributor has total advance of 15 degree. 30 at the crank. The travel in the slot = .430 inches. That is the travel of the pin. Not the total length of the slot. I was able to confirm this with the 2 56 screw.


The other pictures are of the disassembled distributor.

That small flat M looking piece is the lock for the reluctor to the shaft. POS. I will replace with a roll pin.

The last is my idea of adjustable. I will have to cut the head off and put a small slot in the screw itself. Not enough room for the lock washer nut and the head. Oh an I know the total movement is .430 because if I screw in the 2 56 until it touches the pin and then count the turns until it bottoms the pin at minimum advance I get just under 13 turnes. 56 divided by 13 = .430. So each turn of the screw will reduce advance by 1.15 degrees. So once I get the idle set via vacuum and back off 1 " per crackedback, it will be easy to set the total mechanical to the advised 35 degees.

One think I think this does show is that all distributors are not alike. Once I get it dialed in I am going to take apart the old distributor and see what lind of advance it was offereing.
 

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I was editing the post. No they will not clear as shown. I wll either cut the head off once I have it close. Or shorten the screws so when they are fully in the advance will set where I want it. There is .18 inch clearance between the plate and the inside wall of the distributor. Enouch room for head and nut but no lock washer. Tight no doubt. Now the other option is to use shorter screws and screw in from slot side. To get to around 8 degrees I have to screw the 2 56 in about 6 1/2 turns. That is a little over 1/10 of an inch, so the head is .845. So likely in that option I can get from 9 to 5 with no problem.
 
I have to say I LOVE THIS thread. Awesome work. Nice teamwork with the wife!

In order to get rid of the lock washer have you considered a nylon insert lock nut instead. Fashion up a small deep socket with a lever to lock the nut and a driver/allen to adjust the screw and your golden. I use to use something like that when adjusting valves on my gsxr1100.

I know it's more work, could the outer edge of the advance plate be thinned?
 
Another thought is a 2-56 black alloy set screw. They are available up to 3/4 inch long and have a allen style drive. Figure out length and top with a lock washer/nut or a nylon insert lock nut.
 
This seems like the better solution. Not a lot of room for nylon lock nut, but maybe. I know where you are going with this. The option to adjust in the car. Allen can go inside the lock nut, so likely at least two or three degrees adjustment with one length. I like it. Let me see if I have any nylon lock nuts to see if they will fit. Will have to drill the adjustment hole out a bit, but no big and I can put a plug in after. I think that once the final adjustment is reached it will be best to Identify the total movement and then use the cap screws coming in from inside the slots. I am a bit concerned with long term with screw locked from outside the plate. Vibration could allow it to loosen and that would be bad.
 
The nylocks I've seen are 1/4" nut and about 9/64 height, so under your .180 mark. The allens are in these lengths.

1/4"
5/16"
3/8"
1/2"
5/8"
3/4"

So there should be a length that would allow for a decent range of adjustment

Not gunning for doing it while still installed in SB car, be pretty tough. On a BB car that would definitely be a shot.
 
The set screw is a sweeeeet idea. Delete the head and put a flat blade slot in the end ? Delete the jamb nut and apply epoxy based bond like found in most electronic assemblies ?
I would bet the wall above the threads is thin enough so a punch score would create interfearence in the threads.
Regardless... I'm tuned in. Thanks, Ben
 
a dab of rtv silicone on the nut and a tiny bit on the threads may be the hot ticket
 
...a stupid random thought. I wonder how effective adjustment would be if the screws were relocated to the angles? You'd clear the housing then. It would still limit travel even though it would be coming in at an angle.
 
That is an idea. Might not get as much total possible adjustment. Maybe grind a notch where there is more meat and come in at a slight angle. Say 70 degrees. The hardest part about this mod is the drilling and tapping. IF anyone wants to send me old advance plates, I can do some more experimenting. It would be nice if you could order just the plate.
 
This is GREAT I'm gonna have to do some ponderin' on this

like-3d.jpg
 
Abodee,

Yup me too. But I do know that I was getting somewhere around 50 degrees total when the initial was around 20 degrees, so likely it will be close the the same. I did order a replacement that matched the original. I figure these 73 era distributors were set to run on motors set for smog. Like 6 to 8 degrees initial. Which with total 30 degrees advance in the distributor would bring total to around the target of 36 total mechanical advance. I think what I am going to do is dial this new distributor in to 8 degrees. 16 total at the crank. Then put it in and see where the vacuum approach to idle takes me. My guess is I will be close. But I can cut the screw to allow me likely 2 degrees either way. So should be good. I will take pictures of the final plate. I think I am going to cut the screws down to thread in from inside the slot. It is easy to dial in the advance with my mickey mouse degree wheel. LOL !!
 
You could use two setscrews.One longer one for your adjustment and then a short one ran in against the first to lock it in place.
 
OK So here is an update. The idea will not work as shown. I made the mistake of putting the unit into the diss housing without the sensor plate. I assumed the the sensor plate sat above the advance plate so that it would not be part of the equation. So I was wrong. There is likely no more than 1/32 between the advance plate outside edges and the two screws that hold the sensor plate mount to the diss body. So my final solution to thread the screws in from the slot side is not only a mechanically more reliable approach, but it is also a necessity. So for now I have locked in 8 degrees. I think that is a good starting point based on the likely 20 degree initial. I will post pictures of the final plate in the next day or so. But just imagine the same screws you see threaded from inside the plate slot. The end of the screw ground down to be just exposed past the outside edge of the plate. I still like the idea because it appears that each small lock washer or a thinner washer will allow 1 degree changes.
 
Old school ignition bluepring,bad ***! Some needs to sticky this thread ,when finished.Why spend a ton of bucks on aftermarket,stock stuff works as well.Great idea,thanks for the post.
 
Fishy

I downloaded from net. PM me and I will email you the image. I modified so it prints on a 8.5 X 11 paper.
 
I did some figuring...

On that 15* plate, if you thinned the outer edge to .125 you could put a .375 set screw in and have adjustment from 13.5* down to about 6*. If you thinned a nylon insert lock nut down from ~.140 thick to in the .100 range, the adjustment increases to 4* or 8* total mechanical advance.

It's really easier to get the adjustment down to almost zero with a plate with less advance because the overall width is the same regardless of amount of advance. You can remove more of the outer side edge, it's thicker.

Could the plate screw be shortened?
 
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