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Old 10-01-2019, 04:10 PM   #1
Joop
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Default Timing a B engine with A Distributor

..
Have been checking the website but can't find what I am looking for.

How do you time a Model B engine with the "B" timing cover and the Model A distributor with modern point setup.
Car runs good on the top side of the quadrant (until 9 o'clock position)
then runs very bad towards the bottom end.
Timing was set as you do on the Model A but "B" is 19 degrees BTDC
Would prefer not to change the timing cover.

See pictures of timing cover. (one is from the Vince website)

Thanks.

...
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Last edited by Joop; 10-01-2019 at 05:06 PM.
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Old 10-01-2019, 04:38 PM   #2
Joe K
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Default Re: Timing a B engine with A Distributor

You either need to get the correct Model A timing gear cover, re-drill your present cover at the other end of that boss (possibly inexactly) or time using an indicator kit and a timing light. Timing with the timing light can be challenging since you don't get the modern advantage (I'm showing my age here) of loosening and turning the entire distributor to change the timing. But perhaps no more challenging than timing with a pin.

The problem is the 19 degrees is "built in" to the Model B distributor - and the Model B timing cover is designed to work with the B distributor - and no others.

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Old 10-02-2019, 08:16 AM   #3
Hoop
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Default Re: Timing a B engine with A Distributor

Your timing is set at 19 degrees BTDC ... CRANKSHAFT degrees. On the distributor, that's 9 1/2 degrees advance since the crankshaft turns 2X the distributor.

The objective is to eliminate that 9 1/2 degrees of advance at the distributor.

You do this by adjusting the rotor just like you do all Model A timing.

Set the timing as you would a Model A. Make a mark to reference where the rotor lines up to the distributor body. Make another mark 5/16" on the body in the OPPOSITE direction of the rotor's rotation. Move the rotor (pin is still in place and engine does not turn at any time) to line up with the new mark and tighten it down.

(Do the math on the circumference of the distributor and you can convert the degrees to inches.)

This causes the rotor to arrive at the firing point later ... retarding that 9 1/2 degree advance (19 degrees at the crankshaft) and giving you 0 degrees of advance.
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Old 10-02-2019, 09:01 AM   #4
Joe K
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Default Re: Timing a B engine with A Distributor

Quote:
Originally Posted by Hoop View Post
Your timing is set at 19 degrees BTDC ... CRANKSHAFT degrees. On the distributor, that's 9 1/2 degrees advance since the crankshaft turns 2X the distributor.

The objective is to eliminate that 9 1/2 degrees of advance at the distributor.

You do this by adjusting the rotor just like you do all Model A timing.

Set the timing as you would a Model A. Make a mark to reference where the rotor lines up to the distributor body. Make another mark 5/16" on the body in the OPPOSITE direction of the rotor's rotation. Move the rotor (pin is still in place and engine does not turn at any time) to line up with the new mark and tighten it down.

(Do the math on the circumference of the distributor and you can convert the degrees to inches.)

This causes the rotor to arrive at the firing point later ... retarding that 9 1/2 degree advance (19 degrees at the crankshaft) and giving you 0 degrees of advance.

I can see this would work and is akin to the "timing light" method I gave earlier except no timing light required.

How about removing the timing gear cover, and marking and drilling the timing gear with ANOTHER dimple 9-1/2 degrees of rotation away from the present dimple? If I have the thought correct, this wants to be AHEAD (clockwise) of the present mark (you're trying to match that "upper ended" Model B timing gear boss drilling. TDC is still TDC)

Of course one will have to be careful not to confuse the drillings henceforth.

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Old 10-02-2019, 09:43 AM   #5
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Default Re: Timing a B engine with A Distributor

I would remove #1 spark plug, bring #1 piston to TDC on compression stroke and set the points at just before starting to open, same as you would using the timing pin method. Simples.
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Old 10-02-2019, 10:05 AM   #6
Joe K
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Default Re: Timing a B engine with A Distributor

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Originally Posted by katy View Post
I would remove #1 spark plug, bring #1 piston to TDC on compression stroke and set the points at just before starting to open, same as you would using the timing pin method. Simples.
This would work too, except loose motion in your connecting rod bearings might make the actual TDC a little "dicey."

I could see as much as 10 degrees of fudge here depending.

You time using this method with "lost motion" always in the direction of motor rotation (i.e. "taken up.") But pistons are (can be) actually "thrown" ahead at speed thus reversing this lost motion.

Worth a try though - cheap money.

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Old 10-02-2019, 01:25 PM   #7
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Default Re: Timing a B engine with A Distributor

Do not change front cover its not needed..time it without the pin ..so easy see my other posts ..model A and B is the simplest motor evey ....even simpler than model t..bring #1 up to tdc set rotor to #1 and then fine tune..sc
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Old 10-02-2019, 06:35 PM   #8
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Smile Re: Timing a B engine with A Distributor

Joop,


As mentioned in a couple of earlier responses. I visually bring #1 cyl.
to TDC by removing the sparkplug. Once that is done timing is just like
for any A-Model. The motor in my '31 roadster is a "B" block with a "B" timing cover and a "A" dizzy with modern points/condenser.


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Old 10-04-2019, 08:32 AM   #9
Joop
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Default Re: Timing a B engine with A Distributor

THanks for the good info on this and will work on it when back.
Now on or way to Kanab
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