cjmarzoli

1931 Dual Point Timing- Advice?

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I have a 1931 Buick Model 8-60.   It has been stored for many years and I’ve gotten it running and am attempting to set the ignition timing.  It was clearly not firing correctly to begin with.  I installed new wires and condenser, disassembled and cleaned the distributor, and inspected the points (which look good).  I’ve followed the procedure in the original shop manual verbatim.  I can correctly setup Cyl #1 at TDC on the primary points but when I turn the crank to Cyl #6 (with the #6 mark on the flywheel in correct position), the rotor in the distributor has already passed the #6 firing position and the points are already wide open.  You are supposed to adjust the secondary point plate so they have just separated at this position but there is not enough adjustment in the plate for me to close the  points at either extreme of adjustment.    It seems as if the distributor shaft is turning faster than it should be in relation to crankshaft rotation.  I have attached before and after pics of my distributor and pics of the gear sprocket.  There is some thinning of the teeth on the sprocket (in the center section) but would this be enough to throw the distributor rotation off that much?  There is minimal rotational play in the distributor shaft.  However if you rotate the shaft counter clockwise with your hand, there is some rotational movement and the centrifugal advance mechanism opens up.  Is this correct behavior?  After I set the timing the 4 plugs on the primary are burning nice and clean and the 4 on the secondary are fouling.  The car runs better (but not well) now with the spark lever in the retarded position.  It almost dies in the “running” position.  Any tips or theories would be appreciated.  Thanks!

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If you have 4 cylinders mis-behaving, it may not be the timing. Especially if you have timed it according to the manual. The gear cant cause your problem. (yours doesent look bad).

There are steel tubes in the carb heat riser. these can rust and develop holes and thus  vacuum leaks. That will cause poor running. Or having 4 cylinders go out to lunch.

 

Both my '31 and '32 did that to me.

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Thee dual point distributors are a nuisance to get set.  The problem will not be your distributor gear.  First issue is to set the point gaps to .020"  You can do this by having the clamp screw loose and turn the distributor body to get the fixed set of points fully open.  Set the gap rotate the distributor for the second set of point fully open adjust the gap.  Next process is easiest done with the plugs removed.   First make sure you have paint marked the timing marks that appear in the timing hole.  Set distributor spark advance full advance.  fully clockwise in the spark advance slot.  Crank engine by hand until #3 exhaust valve closes.  slowly crank the engine till the 11 degree mark is lined up with the mark on the timing hole edge.  No backing up must be set cranking forward.  Now rotate the distributor clockwise until the distributor wire terminal is facing the front.  At this point,  the rotor should be pointing at #1 wire terminal in the cap.  I prefer to use an ohm meter to make the next setting ( the manual says hold the coil high tension wire near the distributor  and watch for a spark.  With the ohm meter, make contact with the wire to the fixed set of points and the other wire to ground.  very gently turn the distributor clockwise until the meter jumps to zero.  Lock the distributor in this position.  Note this is 11 degrees before top dead center.  now crank the engine by hand to the synchronizing mark 1/4 of a turn on the flywheel.  NO backing  up!  Plugs removed make it easier to crank.  backing up will get cam and distributor gears floating in their lash.  Loosen the locking screws for # 2 set of points.  turn the eccentric screw clockwise until the points just open.  Use the ohm meter to determine point opening  just like the number one set.  Lock everything down, install plugs and you should be good to go.

 

I forgot to mention that you have a mechanical flyweight advance under the points plate.  with everything locked down, you should be able turn the rotor clockwise and let go and it should snap back.  The fly weight will give you from 10 to 30 degrees advance based on engine rpm.  I like to make a chalk mark on the crankshaft V belt pulley  at the 11 degree setting.  You can then use a timing light to watch the advance when the engine is running.

 

I hope this helps.

 

 

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Your distributor looks very similar to the 660 used in the Dodge 8. Here is a page from the Standard Auto-electricians manual about it:

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Thank you.  I have set the timing according to the book as Robert Engle outlined, with the exception of the point gap spec being .018 in my manual.  The issue is when I turn over the ¼ turn after setting the primary points on #1, I cannot adjust the secondary points so that they just open at this mark in the rotation.  The rotor has already cleared the #6 plug wire port and is heading for the next plug, and the points are full open.  There is not enough adjustment to rotate the plate to close them.  The high point of the cam lobe has spun too far prematurely so they are already open much more than they should be at the #6 mark on the flywheel.  This is why I was suspecting the gear as it seems the distributor shaft has turned too far in relation to where I set #1.  I may well have a vacuum leak and will check that system out but that would not cause the distributor shaft to turn too “fast” relative to crankshaft rotation.  Trying to get ignition in order and then move on to carburation and vacuum. 

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One little thing I notice is that the rubbing blocks are different. This one appears to be leaning over. It may even be falling off.

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In your first post you state the points are set at tdc  #1Setting should be 11 degrees before tdc.

 

Bob Engle

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I set #1 correctly at the 11 degree before mark, i just expressed it incorrectly in my post.  Thanks for clarifying.  

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When I set mine I use a tool sort of like the Delco Remy one shown above. It is a set of lines at 45o, intersecting at the centre, mounted on a piece of cardboard that fits snugly on the top of the distributor. Using the tool, the points are set with no reference to timing, which can be done later. Many do this on the bench and set the timing when they re-install the distributor. I just drew it up in a word processor or similar which has a rudimentary ability to specify angles between lines and diameters of circles.

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It actually should work fine , setting these after the manual, what I have found (the hard way)  it is extremely important the points have the right dimension, that is length of  contact arm, take up point of the rubbing block  on the arm,  in relation with the cam lobe .

If these do not have the original factory intended dimension , it can and will not function, the overlapping is not as it should be with the wrong dimension points. This might help knowing  Johan

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Spinneyhill, do you still have the word processing file you created?  If so maybe you could email it to me.  thanks!

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What marks do you see in the timing cover as you turn the engine through 360 degrees?  My info is based on 1932 Buicks the second mark on 32 buicks says "sync" and the first is 6 degrees on 50 series, 11 degrees on 60 series and 10 degrees on the 80,90 series.

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6 hours ago, cjmarzoli said:

Spinneyhill, do you still have the word processing file you created?  If so maybe you could email it to me.  thanks!

Sorry, I had a good look for it last night and can't find it. It may have been in Word Perfect, whatever I was using 20+ years ago. There have been two or three computer changes in between too! I'll make up another soon, my "tool" is about had-it. I attach a bent nail to the rotor as the pointer and line up a line on the first points opening. The others open on the next line.

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OK, just rebuilt it in outline in Open Office Writer.

 

Draw a square of dimension equal to the OD of the distributor top. Copy it and paste it, then rotate that pasted square 45o. I found it easiest to see what I was doing to press one right arrow after the paste so I could see the separate square.

 

Draw a line at 0o and fit it across the diagonal of the rotated square. Copy and paste the line. Right arrow the pasted line away. Rotate it 45o. Do this twice more so you have four lines at 45o to each other. Move them to the diagonals of the squares. Zoom in to fit.

 

Draw a circle then make it the size of the squares and move it into the first square. Group and move the other square and lines over it. So now you have a circle with two squares at 45o to each other with diagonals at 45o diametral to the circle. If you want, you can ungroup and delete the squares.

 

Here is a screen snip of the one just made. It is not to size and is for demonstration purposes only. To use this, I stuck it to a piece of stiff cardboard and cut out the circle to fit the distributor. A bit of the centre is removed too so you can access the points. I'll find my grotty old thing and post a picture.

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Edited by Spinneyhill (see edit history)

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Here is my working model. Pretty grotty, but works, with care. The pointer is stored there too! I am sure something better could easily be made out of a bit of metal.

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3 hours ago, Spinneyhill said:

Here is my working model. Pretty grotty, but works, with care. The pointer is stored there too!

 Spinneyhill thank you. I got a kick out of your model. When I tried to explain how I synchronized my points people looked at me like I was from Mars because the only "proper way" is with a distributor machine. I've attached a picture of my homemade tool that might not be exact but it gets things darn close. I discovered that some yogurt container lids were the same size as my distributor and already came with many of the marks needed. I now have a synchronizing tool but this kept a couple cars running and now lives in the car toolbox. Glad to see there are others who still improvise.

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I started making one out of an old steel protractor that would mimic the Delco tool but then I bought a book of shop equipment for Pierce, Studebaker, and Rockne cars and found another tool.

 

Here’s the other tool that was listed in that tool catalog, it’s a Winn Synchrometer... This unit is pretty much what was made available at that time and works well considering, but I have also been given the advice to find someone who has a distributor machine to get it set up right.

 

My Pierce uses a Delco-Remy 660P distributor, very similar to yours, and once setup is done you go by the points breaking, which turns a light off. Setting the dial to a 90 position on the seated set of points then adjust the movable set to the 45 marks. 

 

I bought mine on eBay for $100 plus shipping without the instructions and have seen another one selling for the same price with the instructions since I got mine. A bit pricey, but I still think it is working better than the protractor I was working on...

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And here is a generic dual point distributor page from the Standard Auto-Electricians Manual showing another version of dual point synchronizing the tools.

image.thumb.png.37008a05135c67cf5bd97fd2725d3fb6.png

Edited by Spinneyhill (see edit history)

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Read the Delco distributor tutorial in Spineyhill's second post which states the advantage of the dual point distributor is longer charging time for the coil before points break firing the plug.  This relates to longer dwell. 

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Question 1:  When you set the point clearances did you set each point set to 0.018" with the cam follower on the movable point at the top of a lobe on the breaker cam?  Only one set of points can be at the top of a cam lobe at a time due to the geometry involved.  On the bench you would simply rotate the distributor shaft by had to do this, in the car you would have had to rotate the distributor to get each follower on the top of the hill to set the point gap.  Looking at one of your pictures it looks like the primary point set is open 0.018" and the other is open more like 0.035" which should not be, the points should not open more than 0.018" anywhere in the rotation of the distributor shaft and breaker cam.  Either the secondary points are opening too wide or you have the adjustable breaker plate adjusted way too close artificially holding the secondary point open excessively.

 

Question 2:  When you attach a rotor and turn it clockwise while holding the distributor shaft still the and get movement the fly weights should deploy outward and when you release the pressure on the rotor the flyweights should collapse back to the fully retracted position due to the force exerted on them by the advance springs.  Is that what is happening or does the rotor not return all the way to it's starting position?  That could cause the rotor to have passed the #6 cylinder terminal on the cap with the "Syn 6" mark lined up on the flywheel window. If it doesn't snap back you may have broken, stretched or unhooked springs lurking under the breaker plate and you should remove main breaker plate assembly with points still attached from the distributor so you can inspect the mechanical advance and make sure the springs are hooked up and viable.

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Str8-8-dave

Q1- on the pic i posted this was when i had it on the bench and had removed points for cleaning inner plate so they are not adjusted yet.  Yes i did adjust each set of points to a max of .018 when on the high point on the cam after this pic was taken.

 

Q2- I inspected and cleaned the advance mechanism. the springs are present and it moves freely but seems to move too easily to me.  The slightest hand spin of the shaft and the mechanical advance begins to open.   It does not seem to snap back as firmly as you state when moved buy hand. it seems to have a lazy snap back.  But does move back on its own.

 

My issue is that when the "Syn 6" mark is centered in the flywheel window the rotor has already passed the #6 plug port on the distributor cap and the point are already wide open and i don't have enough adjustment in the moveable points plate to adjust them to be closed or just opened at this point of crankshaft rotation.  Does anyone supply replacement springs for the advance mechanism or is there a test for them to determine if they are still in spec?  thanks

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