Spark Plug Cross reference

[MapleStone]

Can anybody tell me if an NGK A-6 is roughly the same as Autolite 386s.

A tractor that I bought (my Oliver 550) had NGKs in it and I just changed them to 386 Autolites which I feel are the "right" plugs. The NGKs were wet and black when I took them out but the tractor always started great and ran pretty smooth, I was only changing the plugs as a "maintenance" thing.

Opinions welcome.

 

[bill mart]

386 was one of the cross references i saw online as well as 375,376,377 and 378. bill m.

 

[Anonymous-0]

The 386 was a common plug in that era. I run a couple of Wis V4's. I found 388, next hotter plug to work better. Seems like most 18mm plugs were Autolite 386 and 14mm were H-10 Champions in the 40's-60's.

Areo

 

[noncompos]

"The NGK's were wet and black when I took them out..." Wet with what?? Gas? oil? water?...and they shouldn't be black, they should be a light brownish or grayish, with no appreciable deposits...black often means plug too cold or oil getting into the combustion chamber. An engine with such plugs wouldn't ordinarily start easily and run smoothly; was it smoking any while running (white smoke=oil, black smoke=fuel)?? Fascinating...

 

[MapleStone]

That's why I mentioned it!

It always started easy and ran well. There was some smoke but usually only when first started. I was very surprised to see them wet. The tractor hadn't been started in days so I think it had to be oil, but I'm not sure where it's coming from.

 

[Trailer Trash Tractors]

In my opinion, NGK's are best for high revving engines, the wide heat range, copper core pays off
best at high RPM's. For a tractor, Autolites are hard to beat. Tune up Carburator before a plug change, run engine 1 hour, let cool, check plugs.
A little color is good, bone white and scorched = bad [ too hot ]

 

[buickanddeere]

Autolite 3116 and solid core wires unless you are running an AM radio on the tractor.
What coolant temp is it running at? Oil consumption? Is the carb tune dfor smooth running or as lean as possible without missing?

 

[noncompos]

Curiouser and curiouser, as Alice used to say...
"Hadn"t been started in days...", and you took plugs out and they were wet; almost has to be oil (gas would"ve evaporated and water would"ve been beady and/or rusty, usually). If it"s not using oil or water, and the oil on the dipstick looks OK it sounds like you"re getting a little oil past the rings or past the valve guides, etc (not familiar with your engine) but not enough to smoke appreciably or foul the plugs, altho if the plugs were wet with oil residue it has to be close to fouling.
Were all the plugs alike in black crusty/burned crud deposits and wetness, or did they vary??
Hotter plugs may be enough to burn off the accumulating oil, but expect a touch more smoke if they do. Make sure crankcase vent and vent screen clear so no crankcase pressure builds up.