151 "MUTT" SPARK PLUG MODIFCATIONS
If you’re a purist and have a show vehicle, you might not want to do this modification
Owners and drivers of Mutt's all know that the MUTT is sluggish and seems under powered. My intent was to increase the power
output of the stock engine. With this in mind I set out to make the MUTT more a performer both on the street as well as
off-road, without an engine swap as many people said was necessary. Of the many vehicles that I have installed these plugs on, all
of the owners have expressed an appreciation for the extra power as well as a cleaner exhaust.
Here are several reasons why you may want to install these plugs.
A) Utilize longer life, late model technology spark plugs.
B) Retain the original waterproof ignition system.
C) Cleaner burning fuel mixture = better fuel economy.
D) An engine that lasts longer and pollutes less.
Tools required:
A) Spark plug wrench.
B) Person with a lathe or machine shop to due the work for you.
Parts required:
A) 4@ plug adapters (readily available at you MUTT surplus supply dealer)
B) 4@ Bosch Platinum 4 plugs part # 4477 or 4478 (4477 is a colder range plug)
Procedures:
Chuck each spark plug in the lathe (one at a time) and remove the spark plug threads leaving 3/8"
of threads at the washer shoulder (with washer removed). The plugs could be used as purchased,
however due to the extended reach threads, the exposed threads that protrude into the combustion
chamber could cause auto ignition problems. Also carbon build-up on the exposed threads could
make removal difficult if not impossible in the future.
Do not attempt to re-gap the plugs, even the point type ignition system has ample spark to fire
across the factory gap of the plugs. I have used the point type of ignition in excess of 7,000 miles
over a 2-year period without any related ignition problems. The other vehicles, some with
electronic ignition, have experienced the same level of reliability.
The extended reach plugs do not interfere with the piston at T.D.C. of the stroke, in fact the longer
reach plugs promote a better, cleaner burn of the fuel mixture because of the location of the start of
the flame spread at the center of the combustion chamber.
After all plugs have had the threads removed (with the exception of the 3/8" by the washer
shoulder) install the washers back on them, then install them into the plug adapters, and install them
in the head, hook up the plug wires and start your engine!
Enjoy the added power of a cleaner burning engine. You may notice a slight increase in fuel
economy, if you drive in the same manner as before.
If anyone has any suggestions about this or any other performance enhancing
Modifications to the MUTT they can contact Ron Rietfors at dynasty@ilhawaii.net or fax me at 1-808-885-4976