Model B Engine timing advice in Model A

S

SAXBY2

Senior Member
Need help to set up timing on Model B '33 4cyl Engine in a Model A.
It has the Model B block with C head and B timing gear cover but with stock A distributor.
We found TDC with piston at top of stroke, and timing gear has a dimple that is in sync with
TDC, etc.. The engine appears to be too advanced at full retard.
What should be done to get the typical model A sound at full retard ?
Should the cam be turned in a particular direction by feel to get the typical full retard model A sound?
 
I had the same problem a few years ago and Fordbarn came to rescue. Time it the usual way with the timing pin only set the spark level half way down not full retard.
 
Thanks, that makes sense to comport with the B engine 15 deg or so offset from TDC (or approx 1/3 to 1/2 of the distrib body notch opening).
 
As above or you could use a Model A timing gear cover. The "C" head is slightly higher compression than an A head so you will have plenty of advance. To overcome that, you could set the timing a couple of degrees retarded by putting the lever a notch down when setting the timing.
 
The B timing gear cover has an elongated boss where the pin is kept, the A cover has a round boss. With the pin engaged with the cam gear it is at 19* BTDC with the B cover. The A dist should be set at TDC.
 
Jim Brierley said:
The B timing gear cover has an elongated boss where the pin is kept, the A cover has a round boss. With the pin engaged with the cam gear it is at 19* BTDC with the B cover. The A dist should be set at TDC.
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Piston 1 should be at TDC ,but with the spark rod down on the quadrant as in post 2 with the elongated boss B cover to position the rotor ?
 
Sooo...... If I'm understanding this correctly.....

There are 11 notches on the spark advance lever.

One notch down on the spark advance lever equals 4° advancement of ignition timing.

For timing a model A, with Model B engine, with model B cam cover, and Model A manual distributor, the adjustments should be as follows:

1. Use timing pin to find dimple in cam gear. (This will be approximately 19° advanced from TDC....which would be correct for using a model B centrifugal distributor.)

2. Lower spark advance 5 notches down. (?)

3. Set point gap to this setting. #1 cylinder.

4. When starting, bring the spark advance to 1 notch down as, normal.

5. For driving, use spark advance as normal.


comments welcome

eog

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Thank you Ec. old guy for summarizing it better than I. That's the way I understand post 2, by moving the spark lever down approx. 1/2 way, or 4 or 5 notches, and position the rotor to distrib (plastic) body at the #1 cylinder contact. The points gap would be set at the high cam lobes with the lever down as well.
 
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SAXBY2 said:
Thank you Ec. old guy for summarizing it better than I. That's the way I understand post 2, by moving the spark lever down approx. 1/2 way, or 4 or 5 notches, and position the rotor to distrib (plastic) body at the #1 cylinder contact. The points gap would be set at the high cam lobes with the lever down as well.
Click to expand...

I'm wondering how much practical difference it would make if setting the timing to either 4 or 5 notches. Does it make enough difference to narrow it down to one or the other?

I believe the reason for one notch down on start, is to make sure the spark plug fires after TDC....or, is that correct?

eog
 
EOG, not sure it would make much difference with 4 or 5 notches to start the process. The problem is that the B engine with C head and timing hole in elongated cover boss for the B block was designed to use the auto advance distributor with the ability to fine tune the housing by the side notches. By timing with the lever initially half way down , fine tuning the rotor position by ear or moving the spark lever and resetting the rotor that way may achieve the proper running engine sound with lever all the way up. With a high compression head, the spark lever doesn't seem to need as much movement range as compared to a stock head.
Initial timing with the lever one to 2 notches down the quadrant didn't provide enough retard, hence the questions in post 1.
 
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Read the sections of Model A/Model B over at www.fordgarage.com.

I sort of went through similar in setting up a Model B engine/Gordon-Smith compressor - and wanting to maintain the centrifugal advance of the Model B (An air compressor SHOULD self adjust for best power/economy depending on the "unloading" of the compressor.)

My path forward was to use the Model A block - find a Model B timing cover - and use a Model B Distributor. Effectively converting the Model A engine to Model B timing.

Vince Falter at above site goes through the "style variants" of the various timing covers - including the cover which depending on drilling could be used on either Model A or Model B. https://www.fordgarage.com/pages/timingcovers.htm

At any particular time SOMEONE is selling what they think is a Model A timing cover on Ebay, but in actuality is a Model B cover.

I wonder how many people struggle with their Model A manual timing after the purchase?

Joe K
 
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Thanks for the input. Am familiar with the Falter site, but there is no apparent info. on how to simply set timing for those not wanting to use a B distributor but with other engine components Model B .
 
SAXBY2 said:
Thanks for the input. Am familiar with the Falter site, but there is no apparent info. on how to simply set timing for those not wanting to use a B distributor but with other engine components Model B .
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Technically, all you need is a Model A timing cover to mate with the Model A distributor. The Model B cover matches the Model B distributor. It's the mix-match which screws things up.

A model A timing cover can be brought to your door from Ebay for less than $25.

The span from full retard to full advance on the Model A is about 40 degrees crankshaft. The span for the Model B is about half of that (Ford learned that the adjustment range of the Model A was entirely too large and narrowed it for the Model B)

So adjusting your advance to about half - as others have advised - seems a suitable "mitigation."

Maybe the $25 can fill your gas tank - um. Maybe not...

Joe K
 
IMO, the reputation the B engine has for cracking is at least in part due to the lousy B distributor. I have 3 of them and NONE of them advance like they should (one not at all even though things are free). From that, it seems to me that they are unreliable in getting the correct amount of advance and as we know, an engine running retarded will run hot. That heat causes cracks. Sure, thinner castings might contribute but I think the root cause is the VERY ordinary distributor.
The 3 B distributors I have stay on the shelf where they can't cause any trouble.
 
Question:

If you have a Model A timing cover on a model B engine, wouldn't the engine mounts be a bit different, and result in another issue to deal with?

eog
 
Putting a B engine in an A frame requires that you fabricate or find the different rear motor mounts. I fabricated mine because I could not find the right motor mounts. I am installing the float A motor mounts the modern front mount and had to move the engine forward 5/8 of an inch to get the proper alignment.
 
31a said:
Putting a B engine in an A frame requires that you fabricate or find the different rear motor mounts. I fabricated mine because I could not find the right motor mounts. I am installing the float A motor mounts the modern front mount and had to move the engine forward 5/8 of an inch to get the proper alignment.
Click to expand...

My B engine went in with no issues after I cut the sheet metal lower half of the flywheel housing off the back of the sump and put on an A flywheel housing. Original solid mounts at the rear and the standard A yolk at the front followed by an A gearbox.
 
Eccentric Old Guy said:
Question:

If you have a Model A timing cover on a model B engine, wouldn't the engine mounts be a bit different, and result in another issue to deal with?

eog
Click to expand...

Actually the mounts/frame/bracket interface is the same. The B cover (same casting used for after-production replacement A cover) was changed to "raise" the generator mount hole to better clear the "straighter" lower water pipe. Check out Vince Falter's description.

Joe K
 
I am using a B transmission thus the need to modify the rear engine mount. All this is a result of not leaving it the way Henry meant for it to be!!!!!!!
 
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