carbon fowled spark plugs.

[lamotherl]

Hi lamotherl,
Sept 1952 NAA owners manual shows thisView attachment 73974
Would be a bit higher cranking on 12 volts.

Hi and thank you for this information. Would you you think that when I measured the compression cold, the 110 psi that I measured would appear to be about right?

 

[lamotherl]

I just took the distributor cap off and checked my points for pits. They appeared to be good. I put everything back together and replaced all spark plugs with 4 previously used Autolite 216 spark plugs. After running the engine for about 15 minutes, the spark plugs in position #1 and #2 now have carbon deposits on them. While the spark plugs in position #3 and #4 have only have a small amount of oil on them...no build up of carbon! I checked the spark with a tester while the engine was running and good spark was measured through the wire insulation at 3 and 4. But a with a week spark to the plugs in 1 and 2. What can be my problem? I will get all new wires and all new plugs and test again. but I don't think that will fix the problem.

 

[Eman85]

I'd wonder more why 1 cyl showed high compression. Did you crank the engine the same amount of revolutions when checking each cylinder? Did you hold the throttle open?, needs air to compress. What did you check spark with when the engine was running? Use a spark tester where it jumps 1/4" gap while cranking.
I like the math equation to calculate compression on a 70yo engine. Is this tractor running poorly or are you just looking for something.

 

[Mad Farmer]

My cousin's NAA was running badly and we found 120 psi on #1 and 4, 0 on #2 and 3. Head gasket was shot.

Your comp numbers are good I'd think maybe intake valve seals.

 

[HFJ]

maybe these guys?

 

[lamotherl]

My cousin's NAA was running badly and we found 120 psi on #1 and 4, 0 on #2 and 3. Head gasket was shot.

Your comp numbers are good I'd think maybe intake valve seals.

Thank you for your suggestion.

 

[lamotherl]

I'd wonder more why 1 cyl showed high compression. Did you crank the engine the same amount of revolutions when checking each cylinder? Did you hold the throttle open?, needs air to compress. What did you check spark with when the engine was running? Use a spark tester where it jumps 1/4" gap while cranking.
I like the math equation to calculate compression on a 70yo engine. Is this tractor running poorly or are you just looking for something.

Thanks for the reply.
The high compression number was in position # 3 spark plug. Is this the location of the 1 cyl? I did crank the same number of revolutions
. Four for each cylinder. And the throttle was fully open. I checked the spark with a Lisle Spark Indicator model 19380. My post was asking what could cause my two spark plugs #3 and #4 to be covered with soot or carbon. I since replaced all four plugs after checking my points for possible pits, Now the two pugs that have carbon on them are in position #1 and #2. Maybe there is something wrong with my distributor cap?

 

[Eman85]

How does the tractor run?

 

[wore out]

What can cause carbon fowling on two spark plugs numbers 3 and 4 on my NAA Ford tractor?
Thanks for your help.
Robert

Just as a "heads up", compression numbers and the condition of the oil control ring(s) on a given piston do not necessarily "track".

Compression rings and oil control rings are separate items.

You can have decent compression on a certain cylinder and yet it will "pump oil" if the oil control ring is "bad" and the compression rings are OK.

 

[lamotherl]

Just as a "heads up", compression numbers and the condition of the oil control ring(s) on a given piston do not necessarily "track".

Compression rings and oil control rings are separate items.

You can have decent compression on a certain cylinder and yet it will "pump oil" if the oil control ring is "bad" and the compression rings are OK.

OK! Thank you.