Model B distributor

[Y-Blockhead]

I just bought a Model B distributor. I am planning to experiment with it in two different ways. 1) I am going to run it on s stock engine with the static timing set at 3 to 5 degrees BTDC.

The B distributor centrifugal advance is limited to 17° advance so if you set your initial advance to 3° you will only have 20° total. That is why the B motor is set to 19° initial for 36° total. The B timing covers different from the A cover and sets the timing 19° advanced of the A timing cover.

 

[Denali]

Does anybody know where I can purchase a Model B distributor for my 1934 BB with a 4 banger?

Mark in Fairbanks Alaska

 

[Bob C]

Renner's Corner http://www.rennerscorner.com/distributor-services.html


Ebay https://www.ebay.com/sch/i.html?_nk...ldmodelaparts&_sop=1&_dmd=1&_ipg=200&_fosrp=1


Bob

 

[vonheine]

Bob, Thank You Again. Do you have a photograph of a genuine High Speed Model B distributor cap? I have been searching for days and cannot come up with any historical photographs, period advertising, or data on Model B high speed distributor caps. I have nothing. Why isn’t there a shred of anything on this topic?

 

[Bob C]

Bert's and most of the vendors have this cap.
https://modelastore.com/electrical/distributor-distributor?product_id=4204



Bob

 

[Joe K]

The key is finding one with good shafts,the upper and lower get galled from lack of lubrication.All model A engines can benefit from mechanical advance,detonation is one of the main causes of bearing failure,the hammer effect of detonation is increased with higher compression

And advance.

There is a "sweet zone" which is not readily apparent of course.

The range of advance of the Model A distributor is actually GREATER than the Model B.

http://www.fordgarage.com/pages/bdistributoradvance.htm

Conclusions:

The measurements above show that the initial static Model B ignition timing point of 19 crankshaft degrees BTDC plus a maximum mechanical centrifugal advance of 17 degrees equals a theoretical geometric maximum total advance of 36 crankshaft degrees. The slots in the centrifugal flyweights limit this travel.
Compare this to a Model A distributor which has an initial timing point of 0 degrees TDC plus an actual manual maximum advance of 40 crankshaft degrees. The breaker plate arm slot in the bakelite distributor body limits this travel.
The Model A ignition uses a zero crankshaft degree (TDC) initial timing point so that the engine can be easily started by hand crank, however it should never be run under load in this "retarded" position. The advance lever should always be advanced 1/3 to 1/2 travel (13 to 20 crankshaft degrees BTDC) on the steering column quadrant after starting the engine, and should generally not be run more than 3/4 advanced on the column under any normal circumstances.

The Model B is a higher compression (cylinder pressure) engine which uses more initial spark advance, and lower maximum advance compared to a Model A. This is consistent with the operation of the B engine and the need to protect it from the effects of running too far retarded or over-advanced.

Vince infers that "Full Advance" on the Model A distributor is not required and is detrimental to most efficient engine operation - and recommends against running with the advance lever all the way up. He only generally describes use of Model B additional advance against a high compression head.

Joe K

 

[Joe K]

The Model B cap is the same as the Model A cap - except they narrow the slot at the bottom so it will pass only the wire connector.

Vince's parts list 1932-1934 pix shows the cap as B-12105. http://www.fordgarage.com/pages/bdistributordetails.htm

A Model A cap will work.

Joe K

 

[vonheine]

@BobC Yes, thank you. I have this cap. They are sold by the majority of Model A parts providers. The cap is simply described as a “modern distributor cap” for a Model A Ford. It doesn’t fit on a Model B distributor unless you add a second index pin notch precisely 90 degrees to the existing one that is correct for the Model A. The advance window/notch is still needed to clear the Model B timing reference tab. The cap looks modern, like 1970s modern. It doesn’t look 1930s vintage. Things made in 1930s have a certain look to them. I want to see an original 1930s vintage Model B high speed distributor cap.

 

[raybee]

Genuine Niehoff FF 71 Model B High speed Distributor Cap Ray