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Re: Petronix ignition

To: Lawrie Alexander <>
Subject: Re: Petronix ignition
From: John Turbeville <>
Date: Tue, 25 May 1999 17:46:48 -0500
Thanks a million for the tip. I went out and checked my Pertronix unit on my
Lucas 25D distributor because I had been working on it and also noticed that the
plate moved with the distributor cap off, but when I sucked on the vacuum
advance hose with the cap back on, there was no difference in timing-I kept on
thinking that something must be wrong, it should have advanced the timing a few
degrees. The cap did not properly fit on the bottom side, making it impossible
to see, but when I pulled the whole distributor out, it was very obvious that
the cap does not seat well, so I pulled out the plate and filed it down until
the dist. cap fit down, and whamo! the timing advanced 5 degrees after starting
and sucking on the hose. What a difference it made with mechanical and vacuum
advance working properly together! Thanks again.

Lawrie Alexander wrote:

> In the glorious tradition of this (and other) lists, I will start out by
> saying that I have no answer to the question that Steve asked, as I have not
> tried the Pertronix in a T-type. However, I would like to share the
> discovery, just yesterday, of a serious problem with a Pertronix unit that I
> installed in an MGB.
> After installing the Pertronix, I wanted to check that the advance unit was
> working. A vacuum pulled on the unit made the plate move when I looked at
> the distributor with the cap off. However, the engine did not seem to
> perform as if it was receiving full advance. I disconnected the vacuum pipe
> at the carburetor and applied vacuum while the engine was running. No change
> in idle speed! Off with the cap, checked the plate again - still moving. A
> break for lunch to ponder this seemingly impossible situation.........
> After lunch, I removed the distributor for closer inspection. Eureka!
> Problem discovered. This particular Pertronix unit was machined in such a
> way that the mounting plate that attaches where the points used to be was
> too wide. In other words, its outer edge fouled the cap, thus preventing the
> base-plate from being rotated by the vacuum unit. The fix was to remove it
> and sand off the excess metal on a belt sander. (A file or bench grinder
> would work, too.) When replaced, it made a big difference in how well the
> engine ran.
> So, all of you who have fitted your distributors with a Pertronix unit, may
> I suggest you check to make sure that your distributor cap is not
> interfering with the P-unit where it attaches to the base-plate. Perhaps
> those of you who do find a problem would be so kind as to let me know so I
> can relay the information to the supplier if - indeed - mine was not an
> anomalous situation.
> Lawrie
> British Sportscar Center
> -----Original Message-----
> From: Steven Tritle <>
> To: <>;
> <>
> Date: Wednesday, May 19, 1999 6:43 AM
> Subject: Petronix ignition
> >Has anyone tried the Petronix ignition in their TD? If so, what is the
> >prognosis?
> >I was tempted to purchase one at Carlisle but didn't.
> >
> >steve
> >52 TD
> >

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