Model B distributor

[daren007]

My B engine with A distributor does not like advance at idle. A little is ok but more and she runs lousy. She is timed properly at TDC. while driving 1/3 advance seems to be the sweet spot for overall driving. If I install a B distributor I am told the timing should be now at 19 degrees before the mechanical advance takes over. This seems excessive. I would think it will affect my idle plus would I get a kickback on starting?

[ursus]

It was evidently not excessive as many B-distributors have been installed in Model-A engines over the years. I have never had to crank mine by hand but have been assured that kickback should not be a problem provided one held the crank correctly, and Ford supplied a crank with the Model-B for both timing and starting.

[coatings03]

I have a model B distributor on my A engine. Best thing I ever did, idle in consistent no issues with going uphill .

Jim m

[Tom Wesenberg]

B engine with an A distributor, but what timing cover do you have?
Remember, a B cover is advanced when the pin drops into the dimple.

[Charlie Stephens]

Originally Posted by Tom Wesenberg

B engine with an A distributor, but what timing cover do you have?
Remember, a B cover is advanced when the pin drops into the dimple.

To illustrate Tom's post. The picture is a Model B timing cover. The timing pin is located in a tapped hole at the top of an oval boss. The Model A timing cover had a tapped hole in the center of a circular boss. A very few timing covers were made for the Model A as replacement parts with the tapped hole at the bottom of the oval boss.

Charlie Stephens

[daren007]

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I have an A front cover but would use a timing indicator. As I read the B is timed 18 degrees BTDC opposed to the A's TDC. This would mean the B is firing before TDC if so I would expect a kickback on starting.

[Tom Wesenberg]

18 degrees won't kick back on the stock engine. I've even started mine with about 30 degrees advance when I forgot to retard the spark lever.

[daren007]

How about with a "Touring cam".

[Railcarmover]

Doesnt matter if its a touring cam,B distributor has the correct advance curve.Total advance is about 24 degrees,perfect for an A ,especially with a high compression head.Stock B points are getting scarce but Renners Corner retrofits them with modern points..drill through the lube port(its usually blocked by the bushing) and drill the cam screw so you can lube the upper shaft.And throw your spark control lever away...

[quickchange]

We can supply new sets of B points if anyone requires them , Derek in a cold freezing NZ back from the hot Reno meet ,

[daren007]

No high compression head.

[ursus]

Originally Posted by Railcarmover

Doesnt matter if its a touring cam,B distributor has the correct advance curve.Total advance is about 24 degrees,perfect for an A ,especially with a high compression head.Stock B points are getting scarce but Renners Corner retrofits them with modern points..drill through the lube port(its usually blocked by the bushing) and drill the cam screw so you can lube the upper shaft.And throw your spark control lever away...

Regarding the oil port that is blocked by the bushing: that is what I have done in the past but was recently told that Ford had started installing oil impregnated bushings of the Oilite type during the Model B period. These are made of porous bronze that allow for oil to pass through to the bearing surface from the reservoir in the oiler port. Supposedly, you only need to drill a hole for access if you have installed non-porous bushings.

I wonder if anybody can cite a Ford reference to this bit of trivia?

[Growley bear]

I could find no mention of an oilite bushing in the Ford service bulletins '32-'37. The "B" distributor on my Model A had an oilite bushing installed when I rebuilt it. To my knowledge it had never been apart except for minor adjustments. It had no oil hole. Unfortunatly I ha to install the newer bushing and drill it for lubrication. It has worked well for many years now.

[Railcarmover]

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

[boo]

when i rebuilt my B dist a couple yrs ago i put in new weights some one made that was supposed to change the advance to run better, anyone else use these weights??

[vonheine]

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. 2) When my second engine is built, with a 5:5:1 head, I will static time to TDC for less total advance. The stock engine will tolerate more total advance than the HC head. What I want to know is, what exactly is a high speed distributor cap for a Model B? I saw one on EBay and I had interest, because I find the quality of diamond shaped distributor caps to be horrible. However, it appeared to have no notch for the Model B timing indicator, or the advance window if used on a Model A. How does that work? It was a Nioff FF-71. I have taken a “modern distributor cap “ for a Model A and simply added a second index notch at 90 degrees to the Model A index notch. Now, I can use this cap on a Model B distributor. The advance window is still required for the Model B to clear the timing reference tab. Any inputs on this?

[Bob C]

I looked in an old Niehoff catalog I have and that cap on Ebay in not an FF-71.


Bob

[vonheine]

The Niohoff FF-71 that was on EBay is sold, gone. It was advertised that it fit a Ford Model B. There is a chart on this forum that confirms that number as a High Speed Model B cap. The cross reference was to an Ampco F-928. There are currently dozens of Nihoff caps on EBay, but those are not what I am talking about. I have the photograph on my phone. I am trying to figure out how to post it.

[Bob C]

This is the one that was on Ebay, the box is marked right but the cap is
not an FF71. https://www.ebay.com/itm/Niehoff-FF-...p2047675.l2557

[vonheine]

Bob, Thank You, that explains it! So, that is not an FF-71 cap. It’s just an FF-71 box. I actually bid on it when it was active. Now, I am glad I didn’t get it. It’s not the correct cap. That answers a lot of my questions. Does anyone have photos of a real FF-71? (A genuine high speed distributor cap for a Ford Model B)

[Y-Blockhead]

Originally Posted by vonheine

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?_nkw...g=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/d...roduct_id=4204



Bob

[Joe K]

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Originally Posted by Railcarmover

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