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Old 05-26-2018, 11:43 PM   #1
mightynova63
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Default Cam / distributor gear back lash?

I purchased my first Model A a few weeks ago. So I I am kind of a newbie to the workings of the model A. I am trying to get the motor running. I have installed a new modern points ignition system I converted to 12 volts and rebuilt the carburetor. The motor turns over nicely and has good compression. The problem that I think I am having is that there is excessive slop between the crank and the distributor. When rotating the motor over to find top dead center if I change direction I can rotate the motor almost 90 degrees before the distributor will start to rotate. If any of this makes sense can someone please help tell me if that is normal. The motor will not run but does spit and sputter. I don't know exactly why the car was parked but I'm assuming from the condition that the car was probably parked 30 or 40 years ago.

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Old 05-27-2018, 12:45 AM   #2
Brentwood Bob
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Default Re: Cam / distributor gear back lash?

Maybe the the timing gear is stripped.
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Old 05-27-2018, 01:24 AM   #3
Chuck Sea/Tac
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Default Re: Cam / distributor gear back lash?

When you time it , don’t change direction. That way there’s no slop in the gears, as that’s the natural tension of the motor turning. Crankshaft turns CW and distributor turns CCW.
That being said, you have some serious wear. Probably in the cam/distributor gears.
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Old 05-27-2018, 07:57 AM   #4
Bill Pursel
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Default Re: Cam / distributor gear back lash?

youtube timing the model a ...there are several vidioe on it and the adress the backlash issue
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Old 05-27-2018, 08:54 AM   #5
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Default Re: Cam / distributor gear back lash?

http://modelabasics.com/home.htm
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Old 05-27-2018, 09:30 AM   #6
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Default Re: Cam / distributor gear back lash?

The gear in the middle of the camshaft gets worn, some are so bad you'd be advised to look for a replacement, The small gear that drives the oil pump and the dist. also wears and can be replaced which will remove some but not all of slop. Do this repair and then learn to account for the rest when timing spark.
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Old 05-27-2018, 12:54 PM   #7
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Default Re: Cam / distributor gear back lash?

When the cam screw is tightened, make sure that ALL of the backlash is in the counterclockwise direction after the cam screw is tightened. Any backlash that remains in the clockwise direction will cause the timing to be retarded to whatever amount of backlash remains in the clockwise direction. Backlash in the counter clockwise direction will have no effect on distributor timing . I set mine with the trailing edge of the rotor tip pointing at the number one time in the distributor cap with No clockwise backlash after the screw is tightened . It may take a few tries to make this exact adjustment . It is always best to remove all of the spark plugs to remove compression . Points gap can either advance or retard timing . more gap advances , less gap retards Ford specs for points gap was anywhere from .018 to .022 . A gap of .018 is right on the edge of the point where the points will need to be readjusted . I mostly run mine on .022 . This setting gives quicker throttle response and more time before the points will need readjustment

To remove some of the distributor timing backlash from your engine , the oil pump and distributor drive gear located in the valve chamber can be fairly easily replaced Snyders lists these gears on page A-129 of their catalog.
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Old 05-27-2018, 01:39 PM   #8
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Default Re: Cam / distributor gear back lash?

Also, there is a very important spring-loaded camshaft thrust tensioner at the front end of the engine. The spring inside of the plunger can get rusty and break, especially in engines that have been sitting around for a long time. This allows the camshaft to walk back and forth with highly variable ignition timing. I found a car like yours and experienced the same set of symptoms - I could carefully time the engine but it would soon spit and sputter so badly I could not drive it. Check this out when you get the timing cover off!
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Old 05-27-2018, 04:19 PM   #9
Purdy Swoft
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Default Re: Cam / distributor gear back lash?

Also Snyders and maybe others offer standard and oversize oil pump and distributor drive gears . they offer two over sizes like .004 and .010 , depending on how badly the center cam teeth are worn .
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Old 05-27-2018, 07:09 PM   #10
mightynova63
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Default Re: Cam / distributor gear back lash?

First off thanks for the help. I was about to pull the motor and throw it in the trash last night. After reading the comments I pulled the valve cover off and pulled the drive gear. The cam looks to be ok. I'm not sure if I should still order a oversize gear or not.

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Old 05-27-2018, 07:19 PM   #11
Tom Wesenberg
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Default Re: Cam / distributor gear back lash?

Yep, start by replacing that worn gear.
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Old 05-27-2018, 11:08 PM   #12
Brentwood Bob
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Default Re: Cam / distributor gear back lash?

That end that you show should not have the sideways wear.
It is called the Tang. It fits snugly in the top of the oil pump.

Last edited by Brentwood Bob; 05-28-2018 at 02:02 AM.
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Old 05-28-2018, 12:07 AM   #13
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Default Re: Cam / distributor gear back lash?

Quote:
Originally Posted by Tom Wesenberg View Post
Yep, start by replacing that worn gear.

.. and the parts up to and in the distributor. Some rotational "slop" is ok and can be accounted for in the timing. Any side to side of the top plate or distributor shaft should be fixed.
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Old 05-28-2018, 06:57 AM   #14
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Default Re: Cam / distributor gear back lash?

Check You Tube there are a lot of videos on rebuilding these distributors. If you decide to replace that shaft you will probably find that the bushings are worn also. The good news is that the distributor is easy to remove to work on.
Why not just do it all now so you can eliminate it from your "might be" troubleshooting list. Be a bummer to get down the road and have any side slop bite ya down the road.
Put your location in your info, there is probably someone near you whose brain you can pick.
Great acquisition, enjoy the adventure, Chap
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Old 05-28-2018, 08:25 AM   #15
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Default Re: Cam / distributor gear back lash?

The gear and tang have a lot of wear.
The advice is Purdy Swofts post will compensate for that.

Randall
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Old 05-28-2018, 08:37 AM   #16
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Default Re: Cam / distributor gear back lash?

Quote:
Originally Posted by Brentwood Bob View Post
That end that you show should not have the sideways wear.
It is called the Tang. It fits snugly in the top of the oil pump.
And check the oil pump shaft for wear, the tang is worn, the oil pump shaft is probably worn also.
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Old 05-29-2018, 08:28 AM   #17
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Default Re: Cam / distributor gear back lash?

A bit of dizzy slop not so bad, a bit of cam gear slop, not so good. But if you have parts out, why not just fix them and replace the worn stuff. In today's money, it's no more than a cuppa at Starbucks.
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Old 05-29-2018, 08:47 AM   #18
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Default Re: Cam / distributor gear back lash?

Not that its bad to fix worn things. But these cars will run(maybe poorly) all slopped out. you probably need to check the simple things first. fuel compression spark. Its unlikely the wear is keeping you from running.
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Old 05-29-2018, 09:10 AM   #19
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Default Re: Cam / distributor gear back lash?

Before you start and run, be wise and drop your oil pan and clean the sludge, along with open valve galley and clean as well. Many a still decent engine is ruined in the first 5 minutes of running after sitting as long as yours appears to have been sitting.
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Old 05-29-2018, 04:33 PM   #20
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Default Re: Cam / distributor gear back lash?

Quote:
Originally Posted by Steve Wastler View Post
Before you start and run, be wise and drop your oil pan and clean the sludge, along with open valve galley and clean as well. Many a still decent engine is ruined in the first 5 minutes of running after sitting as long as yours appears to have been sitting.
2nd on this. Most of us have found a half a bucket of sludge and dirt burying the oil pump that sits at the bottom of the pan.
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