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Ditributor Base Plate

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BACLVBob

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After my comments on electronic ignition - I thought I should come clean about one issue I had with the BJ8 last year. The old girl started to misbehave and stutter on acceleration, I checked the basics and all appeared ok, and I put it down to bad fuel as LV fuel is not the greatest. The problem seemed to go away, and in fact when it did appear, I could drive through it if I was gentle with the throttle. I was unable to find the problem before we went on a run with the club. About 800m later the car was getting difficult to drive and unnerving as I was waiting for it to stop all together. After consulting with Jack Daniels one evening, I had a brainstorm and ran out and tore the distributor out of the car. Everything looked ok but I removed the baseplate, initially to check the centrifugal advance. I gave the baseplate a cusory glance and noticed some wear on the slot that guides the moving part. I pullued on the pin that the vacuum advance attatches to and sure enough, as I pulled, the moving part of the baseplate rotated but also pulled upwards. The slot that the pin is guided by, was worn in one place. The effect of this was as soon as the vacuum advance kicked in the points gap would dissapear because of the upwards movement of the baseplate. I made a temporary repair and the car ran like new again. When I got home, I removed the baseplate and dismantled it. A spot of weld on the worn slot, a bit of work with the Dremmell and that part was as good as new. There is a spring that applies pressure to the movable bit which just needed adjusting to apply more pressure and the pin that the vacuum advance attatched to was bent in the direction of pull, so 2 seconds with the needle nosed pliers had that fixed. With it all re-assembled it now works like new and the timing is spot on at all engine speeds.
A friend who has a BJ8 checked his, found the same situation, made the repair and now has fixed his idle problem that has been bugging him for years.
I'm sorry if this is a bit long winded, but its such an easy fix the an elusive issue and spans across all distributor vehicles I thought it may benefit a couple of you.
 
sometimes Jack "is the Man"

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Re: Distributor Base Plate

[ QUOTE ]
After my comments on electronic ignition - I thought I should come clean about one issue I had with the BJ8 last year.

[/ QUOTE ]

Bob, thanks for the info,
I don't know if all Lucas distributors are built the same. On the ones that I have seen, there are two Nylon buttons that serve as vertical bearings between the top & bottom plates. There is also a spring to keep top & bottom plates firmly in contact against the buttons. The head of the "pin" does somewhat limit vertical movement of the top plate but it would have to be awfully worn to release the spring preload which "should" be more than the point contact tension. Does your distributor not have the Nylon buttons? If they are worn or missing the plate would be very loose. New buttons can be made from Nylon or brass. I've never seen a plate worn so badly.

As I said, I'm not that familiar with what exactly may be in the BJ8 plate.
D
 
Re: Distributor Base Plate

The 'pin' that locates in the guide hole in the base plate is very hard steel, the base plate is mild steel, the movement due to vacuum advance is quite small, so the area of wear is less that 1/4". I have the nylon bushes and the spring, however the wear in the guide hole allows the pin to move in a vertical motion. Repairing the guide hole stopped the vertical motion and consequently the change in the points gap. Clear as mud huh? I have an old distributor somewhere, I'll see if that one is the same and take some pics.
 
Re: Distributor Base Plate

[ QUOTE ]
Clear as mud huh? I have an old distributor somewhere, I'll see if that one is the same and take some pics.

[/ QUOTE ]
I understand. Just surprised that it would wear so much. I emailed a couple of pics to you.
D
 
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