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Spark Plugs 351C 2V
#1
Got the mustang out and started to do some tuning. I plug the plugs out (351C 2V) and notice that they were a little rich. At the beginning of last year I had champions in there and they were grayish in color and looked good. No that I switched to Motorcraft there looking a little too rich. So is it the plug or carb? What is the recommended plug I should use Champion or Motorcraft?
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#2
Someone recommended NGK UR4GP so that's what I've got.

Doc

Doc

[Image: 6y14ea.jpg]

Project started 8-7-10
Completed: All new suspension, rebuilt 351C H Code bored .030 over with mild cam and intake, new 3.50 TracLok, custom exhaust system
Current "mini-project": interior upgrade Undecided
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#3
I run stock motorcraft.

Kevin

1971 Mach 1
408C Stroker
C4 w/3,000 stall
8.8" Rear w/3.73's
Disc brakes all way around.

[Image: 28ivsix.png]




                                                                                             
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#4
sgtjd;61649 Wrote:Got the mustang out and started to do some tuning. I plug the plugs out (351C 2V) and notice that they were a little rich. At the beginning of last year I had champions in there and they were grayish in color and looked good. No that I switched to Motorcraft there looking a little too rich. So is it the plug or carb? What is the recommended plug I should use Champion or Motorcraft?

How many plugs are rich?
If not all, which cylinders?
How many miles on the plugs?
What kind of ignition? Stock points, aftermarket(what kind), other.

Leaving all your plugs in the car, connect a good used or new spark plug to an ignition wire, ground the threads of the plug to the car, start up the car, and see what kind of spark you get.


[Image: 11jmcuc.png]
351C Bold Manners, Brash Attitude
Favorite Teams: Michigan Wolverines and Whoever Is Playing Ohio State.

When I drive past a herd of cows, the cows MOO at me
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#5
How many plugs: 8 are rich looking and consistant
All cylinders are the same after pulling the heads off and taking a look.
500 Miles on the plugs. Very new Motorcraft plugs. They are the plugs spec to the engine
Ingition: Petronix I, standard coil and spark plug wires, distributor and rotor
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#6
It could be both the carb and/or the plugs. The carb may need to be re-jetted to provide a better fuel mixture. The plugs may be too cold if you have made modifications to the engine. On your new plugs look for the area where the ground electrode heat transition stops. What I mean is you should see a transition area where the electrode changes color (slight bluing). This transition should be between the base of the electrode and the first thread on the plug body. After that re-jet the carb if the engine is not burning clean. I ended up a heat range hotter in my Cleveland. BTW I use Motorcraft plugs exclusively in Fords.

Jeff T.

Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.

[Image: 1_12_09_14_10_15_11.png]
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#7
In a stock engine, If all 8 are fat (rich) I would suspect the carb/choke/timing. What changes were made, if any, between the time you used Champion and the Motorcraft plugs? Chuck
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#8
No changes were made to the carb or any other ignition part other than going from champion to Motorcraft stock plugs.
The entire base and tip of the plug is black. The timing was set to 8 degrees and started well at this point. Not sure if I should go up to 10 degrees. Also the Carb is not stock its a Holley 4160 (4V) on an Elderbrock manifold. The gas I use is octane level 93.
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#9
With the engine at operating temperature, I'd start by setting the timing with a vacuum gage, at least go to 10 degrees. Second reduce the jet size 2 numbers at a time until the plugs start to get clean. Check the choke to make sure it is completely off at operating temperature.

Make sure the plugs are the recommended heat range.

Jeff T.

Low buck, touring style, '73 Convertible "rolling restoration", 351c, 2v heads with a shave and a haircut, Performer intake, Holley 650(ish), roller rockers, screw in studs, guideplates, stainless valves, Duraspark / Motorsports MSD, T-5 conversion. 1-1/8" front, 3/4" rear swaybars KYB shocks and some home brewed subframe connectors. Future plans; JGC steering box, Cobra brakes and... paint, interior, etc.

When I die I want to die like grandpa, peacefully in my sleep... not screaming, like his passenger.

[Image: 1_12_09_14_10_15_11.png]
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#10
Champion 3025 with good results.

mike

[Image: 1_11_11_13_11_50_27.png]
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