[DeTomaso] Erratic firing

[Pantdino]

Assuming you're using a timing light triggered by the spark to #1 cylinder and looking  at your crank timing marks, if the ignition box is sending that signal at random times you will see the timing mark jumping all over the place.  

I guess if you see the mark at a stable retarded position you could conclude the timing is retarded, but whether that would be due to the box malfunctioning or some other cause would still be unclear.  But I suppose  if the box has failed the "all over the place" condition is most likely.
(Plug firing while intake valve is still open -> backfire thru carb, etc.)

But then I could be totally wrong.  :-)

Jim Oddie

-----Original Message-----
From: Richard Greenblum <pantera at austin.rr.com>
Cc: detomaso <detomaso at poca.com>
Sent: Sun, Dec 29, 2013 1:27 pm
Subject: Re: [DeTomaso] Erratic firing


The timing chain is a double roller high quality steel unit, and the distributor 
(and entire ignition system) came from Dennis at PPC in CO (I'm pretty sure he 
takes care of the pin issues when he provides the setup).

You're right though, I should check the timing before yanking the box off.

Thanks Sean.

Sent from my iPhone

> On Dec 29, 2013, at 14:51, Sean Korb <spkorb at gmail.com> wrote:
> 
> Um... shears.  The distributor pin shears.  Geeze.  Spell check just
> isn't helpful.
> 
>> On Sun, Dec 29, 2013 at 3:50 PM, Sean Korb <spkorb at gmail.com> wrote:
>> Sounds like the timing is retarded.  Check the timing and see if it is
>> stable.  Sometimes if the distributor pin stears or timing set wears
>> it can get retarded fairly dramatically.
>> 
>> sean
>> 
>> On Sun, Dec 29, 2013 at 3:21 PM, Richard Greenblum
>> <pantera at austin.rr.com> wrote:
>>> All,
>>> 
>>> Rebuilt the Holley because it bucked when under load, otherwise ran great.  
Before putting it back on, welded up the door panel holes in the right door 
because they were stupidly enlarged by the shop that painted the car.  Put the 
carb back on and it wouldn't run for longer than a few seconds before losing RPM 
and misfiring and back firing, then dying.  Assumed it was a bad rebuild.  Put a 
brand new carb on, same symptoms.
>>> 
>>> It also seemed to gain temp from cold very quickly.  I turned on the fans 
(they're manually switched).  The engine immediately backfired twice, so I 
turned off the fans and killed the motor.
>>> 
>>> In between the flat, misfiring, and rough running, it ran smoothly.
>>> 
>>> I forgot to disconnect the battery before welding on the door, then figured 
(hoped) the few spot welds wouldn't do what Jack has warned us about.  The box 
is a Mallory HyFire, and it's been on the car for a long time.
>>> 
>>> Suggestions welcomed.
>>> 
>>> I thought I was going to finally get the car back on the road...
>>> 
>>> Richard
>>> Austin, TX
>>> 
>>> Sent from my iPhone
>>> 
>>>> On Dec 29, 2013, at 11:26, "Stephen Nelson" <steve at snclocks.com> wrote:
>>>> 
>>>> Did some of the Panteras come with 2 bolt mains?
>>>> 
>>>> Stephen Nelson
>>>> 
>>>> 
>>>> 
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>> 
>> 
>> --
>> Sean Korb spkorb at spkorb.org http://www.spkorb.org
>> '65,'68 Mustangs,'68 Cougar,'78 R100/7,'60 Metro,'59 A35,'71 Pantera #1382
>> "The more you drive, the less intelligent you get" --Miller
>> "Computers are useless.  They can only give you answers." -P. Picasso
> 
> 
> 
> -- 
> Sean Korb spkorb at spkorb.org http://www.spkorb.org
> '65,'68 Mustangs,'68 Cougar,'78 R100/7,'60 Metro,'59 A35,'71 Pantera #1382
> "The more you drive, the less intelligent you get" --Miller
> "Computers are useless.  They can only give you answers." -P. Picasso

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