[DeTomaso] Sparkplugs

Henrik Svensson hsv at traen.se
Mon Jul 5 11:48:35 EDT 2010

Hi Dan
Thanks for all the input.
I have an old MDS box that came with the car. Ford Motorsport "Extra Performance Ignition" M-12199-C301. I don't know much about it. I did the same misstake as Mike last year. It didn't pass by unoticed. It run very bad!
I have not verified strength or a-f ratio. Iäll guess I'll have to go to a garage to check the ratio to start with.


Från: detomaso-bounces at realbig.com genom Daniel C Jones
Skickat: må 2010-07-05 16:50
Till: detomaso mailing
Ämne: Re: [DeTomaso] Sparkplugs

> The plugs does look ok to me when removing them, just a very little
> sooty but not as much that is should give me problem when firing the
> engine?!?

With unleaded fuels and additives like MBTE or alcohol, it can be hard
to read plugs.  When in doubt, I sometimes pull a plug from my daily
driver for a comparison.


> Any recommendations regarding Heat Range or electrode gap?

What I have in the database for AFD heads is

 Spark Plugs: 3/4" reach, 5/8 hex, washer seat (e.g. NGK BCP6ES)

which appear to be the plugs you are using.  Have you verified the strength
of the spark and the air-fuel ratio?  I like to use a wide band oxygen sensor
and an ignition tester (one with an adjustable gap that looks like a spark
plug with a grounding clamp).  You mention the MSD ignition.  Is that just
the distributor or also the multi-strike capacitive discharge box (e.g.
MSD 6AL).  What are the gaps currently set at?  Also, retarded timing can
foul plugs.

A properly functioning MSD-6AL should be able to keep plugs firing even
when the mixture is rich.  Mike Drew had the choke wire come loose and
we ran for 140 miles with the primaries choked closed.  If the spark
strength is good, the timing and air-fuel mixture correct and the choke
functioning try the next step hotter plug.  In your case, that would be a

Dan Jones

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