triumphs
[Top] [All Lists]

RE: Bad Coil?

To: "'Randall'" <tr3driver@comcast.net>,
Subject: RE: Bad Coil?
From: "Bob Danielson" <75TR6@tr6.danielsonfamily.org>
Date: Tue, 21 Jun 2005 21:02:05 -0400
Randall,
Back in the Winter when I was installing Dan's harness the ballast question
came up and you responded with the following:

> The Lucas Sport coil comes in both flavors, but I believe the DLB 105 
> is the one that does not require an external ballast.  I would suggest 
> measuring the resistance of the primary winding to be sure.  Around 
> 1.5 ohms requires a ballast, around 3.0 ohms does not.  You can't just 
> disconnect the ballast wire though, you'll have to provide another 
> source of switched power to the coil for the engine to run.

At the time I did the test and got 3.0 which meant, (or so I thought) I
didn't need the ballast, so I didn't re-use it. Plus the car's been running
great since I finished the wiring back in Feb. I assume it wouldn't have run
correctly right  from the start, or could this be a gradual problem build
up?

Bob Danielson
1975 TR6
http://tr6.danielsonfamily.org



-----Original Message-----
From: owner-triumphs@autox.team.net [mailto:owner-triumphs@autox.team.net]
On Behalf Of Randall
Sent: Tuesday, June 21, 2005 8:14 PM
To: 'Triumphs List'
Subject: RE: Bad Coil?

> On the
> negative side of
> the coil, and at the distributor, it reads between 7 & 8 volts and the 
> reading sometimes "jumps to" 11 or 12 volts.

Hmm, have you checked your point gap or dwell ?  That seems a little high to
me.  Could be a bad connection inside the dizzy too, maybe a wire that is
broken internally.  Could the ground wire for your point plate be missing or
open ?

> With the key in the On
> position, but the car NOT running, I get the same 12.5 on the + side 
> and less then 1 (actually 0.25) on the negative side.

My apologies if this was covered, Bob ... a 75 TR6 should have a ballast
resistor built into the wiring harness.  This measurement means yours has
been removed.  Do you know which Lucas Sports coil you have ?  The proper
coil for a 75 TR6 requires the external ballast ... if someone sold you the
proper coil then you may be overheating the points and/or coil due to lack
of a ballast.

Easiest test for a bad coil, IMO, is to substitute with a known good one.

Randall




<Prev in Thread] Current Thread [Next in Thread>