I've seen a faulty coil cause similar symptoms. Best diagnosis procedure is
to try one thing at a time - start with a NEW (not one off the "spare parts"
shelf...) coil and recheck the timing. Set the static timing manually - #1 @
TDC and set the disti to fire at that point. If backfiring thru the intake,
then the timing is too far advanced. Don't rely on a strobe! Then check the
plug wires -if there's cross talk, they could be firing at wrong times. My 2
shilings...
Brian
1967 TR4a
------------------------------
Message: 3
Date: Mon, 19 Nov 2007 08:42:49 -0500
From: Joe Burlein <supertr6@earthlink.net>
Subject: Re: [TR] Backfiring! Help!
To: Mitch <ms6453@optonline.net>, Triumph List
<triumphs@autox.team.net>
Message-ID: <474192D9.9000808@earthlink.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Mitch wrote:
> Hi Joe,
>
> To get a better idea of the problem more info is needed.
> Does it backfire under load, if so when hot or cold.
Originally under load and when cold, now under idle conditions.
> Is it back firing through the intake or exhaust?
Intake
> Did you put points in and eliminate the electronic ignition?
Not yet, she won't even idle now. This was going to be the next thing I
did as far as troubleshooting before the backfiring at idle happended.
> What do the plugs look like?
Fine, but, they are new. The old ones had the normal color range.
> What does your vacuum gauge read.
If are speaking of the PSI gauge, then 0.
> If you have an 02 sensor with a fuel/air mixture what does that read.
N/A, sorry.
> Did this occur after any changes?
No.
> Any other symptoms, hunting or surging idle, hard starting,
> hesitation, stumbling.
The only symptom I had before the backfiring was a cut out at high RPM
and hard acceleration. That was what made me start to question (after
checking plugs, timing, car leaks, vacuum leaks) the Pertronix. I just
never got around to swapping it out.
Thanks for the help Mitch.
Joe
>
> --
> Mitch Seff
> Oceanside, N.Y.
> 75 TR6 SC
> http://www.triumphowners.com/384
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