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Hagerty Employee

What I learned from testing the limits of an “idiot-proof” design

After my Austin-Healey's BMC A-series engine had left me stranded two times in as many weeks, I discovered that the points were more charred than a well-done steak at Golden Corral. So I sat down and ordered some parts and prepared myself for the task of playing with the ignition timing. That meant reading every manual I could find—I even dove into YouTube and absorbed everything I could regarding how to properly set up a new distributor.


I know what you are thinking, dear reader: Why is he replacing the entire distributor when all he needs is a set of points? Also, didn't Rob Siegel talk about this like two weeks ago? You are correct on both fronts, but hear me out. This article isn't an explanation of my choice to upgrade to an electronic distributor, or the exact how and why of the install. No, these are my thoughts about a word I used to describe the design of the BMC A-series distributor drive—“idiot-proof—and how it came back to bite me.


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I am experiencing a similar situation, and I think the cause is the vacuum advance. I have it blocked off now and will log a few miles to see if it smooths out.

I did align the timing mark on the balancer, but that doesn't mean the number one cylinder is on TDC. That was my error, as I admitted in the article. I didn't want to take the rocker cover off initially because (miraculously) didn't leak and I didn't order a replacement gasket.

I bought the car 4 months ago. I firmly believe in the theory that if it ain't broke, don't fix it. It started and ran smooth when I handed over the cash and signed the title. No reason to immediately start spending money replacing items that weren't worn out.

To be fair, everything fails. There is no perfect design. There is some designs better suited for certain situations though, and I feel this setup is ideal for this car.

I can't say I've ever seen an ad where any ignition system is being sold as "never failing." Marketed as an upgrade for various reasons, sure, but never "failure proof."

I think all of us have "stabbed in" the dizzy and been out. The old Mopar design that was basically like a slotted screwdriver gave you a 50/50 chance of being in or 180 out. Guess how many times I was 180 out?


On points, I still keep a set on hand in case the Pertronix unit fails. But.....the quality of components you get these days is NOT an apples to apples comparison to the points sets of old.

New Driver

Howdy,I'm surprised you didn't just index the base of the distributor and look to see (under the distributor cap) where the rotor is pointing. The distributor drive on most Hondas is engineered the same way. Hopefully this helps next time around for you or someone else.

Where number one compression was wouldn't even come into play. Firing order is a whole different issue though.

Oh well, live and learn... Get 'em next time...




This is one reason I like to work on my own cars - when there's a problem, I always know who to blame!



There may not be any mechanical device that's 100% idiot proof, but speaking as a full fledged idiot, I can say 1960's Volvos come pretty close.  I was driving my 1965 122S to work one morning and the the engine didn't quit but the power output went to near zero.  I looked under the hood and found that the collar that holds the distributor in place had failed and the distributor had gone to full retard.  I tried advancing it and hoping it would stay in place but as soon as I started driving it went to full retard again.  This was pre-cell phone days and I thought if I walk home or walk to a pay phone and call a cab, I'll show up at work about noon my boss will not be pleased.  In desperation, I removed one of my shoe strings, tied it to a secondary terminal on the distributor, adjusted the timing to about where it was supposed to be and tied the other end of the shoestring somewhere on the engine.  I intended to do a permanent fix as soon as I got home, but with one thing and another I ended up leaving the shoestring on there for about a month before I finally got around to repairing the distributor locking collar.   

Intermediate Driver

The author was at #4 TDC compression instead of #1 which was at overlap, end of exhaust beginning of intake, both valves open at the same time. Next time with all spark plugs removed turn the crank over by hand with the tip of your finger over #1 hole until you feel compression then continue to turn the crank up to the BTDC # specified and install your dist. This way you don't have to pull the rocker cover off.