Distributer

Gufshoz

Gufshoz

Member
I need some advice. I time my '30 A according to Les Andrews book, with a test light. I set the engine at TDC and the spark lever at the top position, then I rotate the distributor cam twice counterclockwise before just getting the light on for #1. When I try to advance the lever (pulldown) it wants to go almost to the middle of the segments before the light goes off. The motor will start, but I have to advance the lever all the way and if I retard it the motor bogs down. I did a test drive and I had to keep the motor racing to make it back home. Also it backfires a lot. I know it feels like the timing is off.
Advice?
 
Your timing is obviously off . Try this !!! Remove all of the spark plugs to remove compression . When the engine nears number one time it gets more difficult to turn and causes a person to go past the timing mark . That is why it is important to first remove compression when setting the timing . I first check points gap . Too little points gap retards timing , too much gap advances timing because extra gap causes the points to open quicker . The car mostly runs with advanced or nearly advanced timing . There is really no need to retard the spark when setting the timing If the points gap has already been checked and correctly set . . When the timing pin drops in place , I adjust the distributor cam so that the trailing edge of the rotor tip points exactly at the number one spark plug contact in the distributor cap body . Most model A's will have some rotational backlash in the distributor that is caused by wear . It usually takes a few tries but it is MOST important that NO rotational backlash in the clockwise direction remains in the distributor shaft after the cam screw is tightened . The distributor shafts rides on the clockwise end of the backlash . Counter clock wise rotation or backlash will have no effect on timing or any thing else . To explain why there should be no clockwise backlash is because it will cause the engine to have to turn slightly to catch up the slack before the distributor actually begins to turn . Rotational backlash causes the timing to be retarded to what ever amount of clockwise rotation remains . If you can't make this adjustment , you can always set iit back like you have it now so you really have nothing to lose . Model A's was one of the easiest cars ever to set the timing on when done the way that Henry intended .
 
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If you continue to have issues, the Nurex Timing wrench gets you very close, and insures you take the back lash out of the adjustment, and yes timing is done turning the wrench clockwise. Due to backlash , your adjustment is off by a bit.

Make sure the Points are gapped correctly before setting the timing



Here it is, even has a U tube video showing how to use the wrench If not satisfied, double check with your other method, will be right on or very close.
http://www.nurex.com/nu-rex-nu-wrench
 
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Take all the plugs out like Purdy explained, and hold your finger over the #1 hole. As you feel air building you will know you are almost there. Watch the timing bolt carefully. Another tip is to sharpen the tip of the timing bolt slightly, makes it easier to feel the dimple.
 
Instead of sharpening the end of the timing bolt I just use a short phillips screwdriver to find the dimple.
Also before setting the timing make sure that your points are gaped correctly and the arm on the distributor travels fully to each side of the slot in the distributor body.
 
Whenever I install a new cam timing gear I always enlarge the dimple with a drill , they are all way too small .I also agree with Dave . A stubby phillips screwdriver makes a better timing pin .
 
You have gotten good advise here, but Bob C has identified your problem. You take the back lash out by turning the distributor clockwise, not counter clockwise.
 
Thanks for all the great info. Our regular meeting of our local club, Gulf Coast Model A Club, I was able to discuss this with some of the local gurus. Consensus opinion was to pull the distributor to check the shaft since it had been in place since 70’s. Oh, my, it was covered in forty-year-old grease with quite a bit of pitting. I’m going to get a new, non-electronic distributor with modern points and condenser. When I put my finger down the hole for the shaft I still feel some pitting. I hope that won’t be an issue.
 
Finding TDC on #1 sometimes is difficult if the dimple is very shallow. Try this. Take out all the plugs. While you slowly turn the engine with the crank, insert your thumb into #1 and feel for the building pressure indicating that you are on the compression stroke. Before you get to TDC, insert a 1/4 in dowel down into #1 and lean it against the radiator support rod so that you can see the piston approach TDC while turning the engine. When I get to TDC, I mark the dowel adjacent to the radiator support rod for use in the next test. The 1/4 in. dowel will tell you when you get TDC plus a brief interval at the high point and then it goes down. Very easy to see and find TDC. It is the method I use on my Model T. Ed
 
Wouldn’t the backlash be compensated for buy just rotating the engine in the correct direction when coming up to tdc. ( as long as you don’t back up because you overshot?)
 
Chuck Sea/Tac said:
Wouldn’t the backlash be compensated for buy just rotating the engine in the correct direction when coming up to tdc. ( as long as you don’t back up because you overshot?)
Click to expand...

You are quite correct. Bringing the motor to TDC without backing up would mean the backlash is already taken up BUT when you undo the screw holding the cam, you turn it anticlockwise (the same direction the rotor turns) which introduces as much slack as the drive system has in it. That then has to be removed again before you can get the timing right. I hold the screw with a screwdriver in one hand while turning the cam clockwise to remove the backlash and set the timing, then nip up the screw. Not holding the screw while turning the cam will nearly always allow the screw to turn with the cam and tighten itself in the wrong place.
 
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