How to set initial timing with just a test lamp – David Conwill @Hemmings

How to set initial timing with just a test lamp – David Conwill @Hemmings


No timing light? No problem.

Pulling a distributor can be intimidating the first few times you do it. The distributor, after all, is where the delicate dance between spark and compression is choreographed. Put things back wrong and the engine may not run or may run so badly it’s at risk of damaging itself. Then, even if things are put back together more or less in the correct way, they still require fine tuning.

To get yourself as close as possible to the right starting point, pull out something virtually everyone has, a test lamp (12V or 6V, as appropriate to your car), and use it to find the exact moment your points make contact inside the distributor. Then, when you go to actually start the engine, you’ll already be within a degree or two of the proper static advance.

I recently had to do just that on my ’62 Corvair after combining the worn-out original distributor with a much nicer one salvaged from a 1965 110hp engine. It made getting the car re-started a snap.

The Problem

For quite some time, I’d noticed my car had diminishing power on hills. Because it wasn’t that great to start with, that was a real problem. Although I’d installed a new distributor cap, plug wires, and rotor some time ago, I figured it was time to replace the points and condenser. Yet, imagine my surprise when I discovered they were both nearly new! It was clearly a deeper problem.

I turned to one of the best Corvair resources I’ve found yet: How to Keep Your Corvair Alive! by Richard Finch. The late Mr. Finch was a devotee of the raced and daily driven Corvair and offered up his book as a supplement to the GM-supplied shop manuals (which I also own—I insist on owning a shop manual for all my cars, otherwise I feel I’m just groping in the dark when I work on them).

In his initial tune-up instructions (which, of course, I’d never really gotten around to following until now), Finch describes testing both the vacuum and centrifugal advance systems. One problem, I quickly discovered, was that rust had formed between the centrifugal-advance weights and the plate on which they slide inside the distributor. I pulled them, gave them a gentle cleaning with sandpaper, and then reassembled things—confident I’d be back on the road shortly now that my mechanical advance was working again.

Except when I went to give it the test, the distributor shaft no longer moved when I turned over the engine with a wrench. That was a new and unpleasant development. Down inside the engine, the roll pin that holds the distributor gear had sheared. Something I only discovered once I pulled the distributor to investigate why it no longer interfaced with the engine.

The Solution

Getting new roll pins off the generic-parts rack at the parts store is thankfully no problem. But when I got my old distributor cleaned up for repair, I noticed that the cam inside was really showing its mileage. I think it was probably run without lubrication for a long time. It occurred to me that I actually had a second distributor from a parts engine I’m slowly disassembling. To my delight, it was like new inside and still even wearing what may have been its original points, condenser, and dust shield.

I pulled the rusty, crusty vacuum advance unit off, replaced it with the unit from my original distributor, and swapped in the advance weights for good measure. Then I installed the Frankenstein distributor and went to set the initial timing using another of the Finch tricks: using a test light to know exactly when the points open and close.

Read on

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