Spark Control Rod - Why Can't They Make it Right?

[ahirt]

I have been working on my 28 Tudor for a while, trying to fix big problems first. Just put in a new engine. When I put the distributor on and connected the spark control rod, I noticed that I could not raise the spark lever to the top of its range. It had always been that way but I ignored it. I little investigation showed that the bottom plate on the distributor was as retarded as it would go limited by the distributor body, thus not allowing any more movement on the control lever. However, when I pulled the control lever all the way down, the lever would reach the bottom of its range on the steering column, but it would still have significant range available on the distributor body. Hence, while I was getting full retard, I was not getting full advance.

Now I know that if you have a 2-Tooth steering column you can rotate the steering column slightly to adjust this. The 7-Tooth, which I have, is not adjustable. The only solution is to bend the spark control rod to effectively make it shorter. I have seen MANY 28's and 29's like this.

However, I just picked up a 29 PU and I noticed that its spark control rod looked “old” and straight. So I swapped it on to my Tudor. Lo and Behold, it fit perfectly, the control lever on the steering column has full range of motion and the lower plate on the distributor also moves the full range as limited by the distributor body. No bending or adjusting is required.

So out of curiosity, I measured the two spark control rods. The control rods consist of two end caps, two springs, and a fixed length rod. For the repo, the length of the rod (not counting end caps) is 17”. For the original (and I believe it is original, since the end caps are steel), the length of the rod is 16 and 11/16 inches – or 5/16” shorter than the repo. The length of the original – including end caps is a tad short of 17”. Note that the length of the fixed rod is the important measurement since this length is what determines the distance between the distributor ball and the control rod ball.

SO my question is, why can't the vendors make these things the correct length? It does not cost any more to make it 5/16” shorter, and it would certainly be a better product. For years the solution has been to rotate the steering column or bend the control rod. Why not make it right the first time and just have a “plug and play” replacement? I would certainly be happier.