[DeTomaso] RV: A question I'm hoping you can answer

[Charles McCall]

Hi all,

 

A few weeks ago we debated on the Forum what happens when you let your
engine sit for months at a time without starting it. In my case, the engine
came to life cylinder-by-cylinder, and it literally took about 4-5 minutes
before the engine was firing on all 8 cylinders. 

 

Starting the engine the following day it fired up immediately on all 8. 

 

Chuck Engels and I both have Chuck Nuytten carburetors on our cars (how many
Charles can we fit in one sentence?) and Chuck suggested that I write Chuck
to ask a carb expert what he thought. 

www.chucknuytten.com <http://www.chucknuytten.com/> . Both Chuck and I are
very happy with their work. 

 

Here’s his reply. Sounds like the plug gets covered in dry gas-goo, and it
takes a while to burn this gunk off. 

 

This also answers the hidden question of if my engine was telling me
something by taking so long to wake up. Doesn’t sound like a weak spark,
sounds like a gunked up spark plug that eventually burns clean
 

 

Charles McCall

1985 DeTomaso Pantera GT5-S #9375

"Raising Pantera Awareness Across Europe"

 <http://www.poca.com/index.php/gallery/?g2_itemId=2323>
http://www.poca.com/index.php/gallery/?g2_itemId=2323

  _____  

De: Chuck Nuytten Carburetors - Tech [mailto:tech at chucknuytten.com] 
Enviado el: miércoles, 16 de febrero de 2011 21:10
Para: Charles McCall
Asunto: Re: A question I'm hoping you can answer

 

Any car that is left unused for any length of time experiences drying up of
the fuel leaving a heavy slug or gunk.  This gets loosened up and flushed
through the carburetor into the motor.  It is thick and nasty like old oil.
The missing you have recognized is the spark plug covered with this nasty
stuff causing the spark plugs to miss-fire until it gets washed off and
finally starts to ignite the cylinder once again.

 

Fresh spark plugs installed once the motor has been started and allowed to
run long enough to pass the gunk through the motor should clear up the miss.
The cylinder still has to be ignited to get the rings functioning properly
to dry the inside of a missing cylinder.  Some times rust is formed above
the top ring that needs to be passed out the exhaust port too.

 

Let us know if you have any other questions.

 

-Tech Dept.

Chuck Nuytten Carburetors

----- Original Message ----- 

From: Charles <mailto:charlesmccall at gmail.com>  McCall 

To: tech at chucknuytten.com 

Sent: Wednesday, February 16, 2011 9:41 AM

Subject: A question I'm hoping you can answer

 

Good afternoon Chuck

 

I am a very satisfied customer of yours from several years ago and I have a
question that I’m hoping you can answer. 

 

A few weeks ago I started the engine of my Pantera (A Ford 351C) after not
having started it for 3 or 4 months. 

 

It took a bit of cranking to get the engine to fire, which I perfectly
understand. Over the months that it hasn’t been used, fuel evaporates from
the carb bowls, the fuel line, and who knows where else so I can understand
that it may take a while for the mechanical fuel pump to fill the system. 

 

When you rebuilt my carb you milled off the choke, so my car has no choke.
This is not a problem.

 

When the engine finally fires, it ran on perhaps 5 cylinders for perhaps 60
seconds, when a 6th cylinder joined the party. It ran very rugged for
probably 2 minutes (real minutes) before another cylinder started to
function properly. And it was probably 4-5 minutes before all cylinders were
contributing. 

 

In the meantime, the garage filled with exhaust fumes until the engine began
running on all 8 cylinders. My intake is a Weiand Xcelerator. 

 

I don’t believe that I have any problem with the engine or with my carb. IF
the engine is warm or has been used regularly, it starts immediately and
runs on all 8 cylinders. 

Starting the engine the following day for example, it fired up immediately.
If I let it sit for 3 months, then it wakes slowly again. 

 

My question is more a philosophical question than anything else. What is
happening that causes an engine that has not been started in 3 or 4 months
to not fire on all cylinders until it warms up? With a common intake plenum
and a common carb, fuel should be reaching all cylinders. The whole root of
this question was that I was wondering if my engine was trying to tell me
something – for example I have a weak spark in certain cylinders or ???

 

If you could shed any light on this question I would be quite grateful. And
the DeTomaso forum would be grateful as well. 

 

Thank you!

 

Charles McCall

1985 DeTomaso Pantera GT5-S #9375

"Raising Pantera Awareness Across Europe"

 <http://www.poca.com/index.php/gallery/?g2_itemId=2323>
http://www.poca.com/index.php/gallery/?g2_itemId=2323