Bill Newland

Restoring my 1956 Distributor

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I am in the process of restoring the distributor for my 1955 Buick Roadmaster Convertible. The engine in this car is a 1956, but it has a 1955 distributor in it. That's not good because in 56 Buick changed from a steel camshaft to a cast iron one and so the oilpump/distributor gear is cast iron also. So what I have now is a steel gear (1955 distributor) running on a cast iron gear (1956 camshaft). This incompatibility can cause the camshaft gear to wear faster than the distributor gear, which is the opposite of what you want. Fortunately, the engine only has about 2000 miles on it since it was rebuilt.

 

I contacted the previous owner about this and he gave me the 56 distributor that was previously in the engine. The first thing to do in disassembly is to remove the distributor gear from the shaft. This is done by grinding off one end of the staking pin and driving it out. Reassembly may present a bit of a challenge. I'm thinking of using locktight on the shaft and gear ID and positioning it longitudinally on the shaft so that the .002” to .007” end clearance specified in the manual is achieved. Then, after the locktight sets up, I would drill a new staking hole 90 Deg to the existing one, making a staking pin on my lathe with about .0005” larger OD than the drill size, installing it, and peening it over on both ends.

 

Upon disassembling the distributor, I noticed it was full of dirt and trash. I also noticed that the wiring was very brittle, which would be expected after 64 years. Therefore, I ordered some “BNTECHGO” high strand ultra flexible 16 Ga wire from Amazon. The wires inside the distributor flex when the base plate (Fig 1-52 of the 1955 Buick Service Manual) moves in response to the changing vacuum advance. Due to all this flexing, the wires can fail in fatigue and break (or be on the verge of breaking). I will be replacing these wires using the same terminals (after using a dremel wire brush on them) to solder on to them. Before removing the distributor shaft, I checked the side play and could not feel any. After removing, I found that the maximum wear on the shaft was .0004” and occurred at the lower bushing. Measuring the bushing ID and shaft OD I get .0009” clearance at the upper bushing and .0017” clearance at the lower bushing. The manual simply says, “check for excessive looseness” . The upper shaft to bushing clearance would be the most critical since excessive looseness would cause erratic point gap and timing. I will be leaving the bushings as is and not replace them. Replacing them would require a 6” long piloted reamer.

 

I disassembled the “breaker plate parts” as shown in Fig 10-52. I would suggest placing the breaker plate assembly in a large clear plastic bag to remove the spring “retainer washer” so that it doesn't fly away and get lost. I noticed the cork that Bernie refers to in another post (the 55 manual calls it “felt”). Unfortunately, it went into the parts clearer tank with everything else, and pretty much dissolved. I was lucky to find a NOS breaker plate assembly on ebay and obtained it. I'm reluctant to disassemble it because I have yet to figure out how the small “side spring” is installed (Fig 10-52). I did check the friction between plates (Fig 10-54) and it requires 25 oz to move the breaker plate (manual calls for 15 oz Max). This was after oiling it with light oil. I don't know what to do about this. I am experiencing the “kick back” (due to too much timing advance) Bernie refers to after starting the engine again shortly after it was previously running with the distributor that is presently in the engine. This problem with the base plate not returning to retard (and probably not advancing correctly either) seems to be an inherent or design problem. The only thing I can think of to do is to use a weaker “tension spring” (Fig 10-52), if one can be found.

 

The manual says to check the distributor cam for scoring or excessive wear. There is no scoring, but the manual doesn't say how much “excessive wear” is. I measured across the lobes where the point block rides (4 places) and I get .9955” with not more than plus or minus .0001” at the other three locations. The measurement at the ends of the lobes is .9963”, This would indicate .0008” wear on the lobes. I'll be using the existing cam.

 

Comments and suggestions would be appreciated.

 

Thanks, Bill

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Thanks for posting this Bill.  I have a distributor that I want to rebuild too so your post is very informative.

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The felt pad I worked with was completely dry and I did remove it. Since it was in tact I gently massaged it between my fingers and saturated it with the oil. I figured it would be fine. I considered making a new one at the time but it was very thin and I didn't have anything suitable.

 

I would drop the NOS one in a pan of 30W oil and let it soak before taking it apart. Should be fine.

 

I do remember that pad being called felt at the time. I remember looking through my cork to find something that thin. It doesn't look like much but it is real important to the way the car runs. That had been the root of the car's poor performance and limited driving for over 20 years.

Bernie

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16 hours ago, Bill Newland said:

I contacted the previous owner about this and he gave me the 56 distributor that was previously in the engine. The first thing to do in disassembly is to remove the distributor gear from the shaft. This is done by grinding off one end of the staking pin and driving it out. Reassembly may present a bit of a challenge. I'm thinking of using locktight on the shaft and gear ID and positioning it longitudinally on the shaft so that the .002” to .007” end clearance specified in the manual is achieved. Then, after the locktight sets up, I would drill a new staking hole 90 Deg to the existing one, making a staking pin on my lathe with about .0005” larger OD than the drill size, installing it, and peening it over on both ends.

Look in the service manual again where it says to use " a shaft shim washer" between the gear and lower thrust washer.  It may not make any difference, but the gear mesh with the cam would change if you move the gear on the shaft.  I put a cast gear on mine 120K miles ago.  Made some shims and installed the gear with a roll pin.  I pull the distributor about every 30K miles to change the points/condenser and everything is still tight.

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Bernie,  I soaked the breaker plate assembly in 30 W oil overnight. It now takes 19 oz to rotate it, still 27% over the Max called for in the manual.  I'll try it as it is rather than trying to figure out a way to reduce it further.  Thanks.

 

Thanks Old Tank.  I'll use a roll pin.

 

Bill

 

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That specification would have "assumed" the pad was lubricated, manuals tend to be written quite optimistically. That little difference probably won't even show. The good part is that the plate will have a chance to slither back to its retarded position while you pay for gas. And that will mean a lot.

Bernie

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I suspect that "excessive wear" would be when the point gap and point dwell readings are not in the desired range.

 

NTX5467

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