spark plugs

[huron]

Anybody know what the proper spark plugs are for a 1983 Johnson 140hp V-4? Is there anything better than the surface gap plugs I've been running?

 

[fluke88]

Re: spark plugs

i have a 1987 johnson 110, i always switch from champion to NGK
dont know what your runnin now, cross reference to NGK if you
want.

 

[Vic.S]

Re: spark plugs

According to Boatsetup.com UL77V or L16V Surface Gap

But according to the "more details" facility on the shop.evinrude.com parts list

L77JC4, the suppressed version QL77JC4 or UL77V

The conventional plugs should be gapped at 0.030" AFAIK

My understanding is that the surface gapped plugs are suitable for sustained high speed use but otherwise use a conventional plug

Suggestions that you should use plugs other than Champions will be stamped on by the experts with great ferocity.

BUT Equivalents and explanation of codes are HERE

 

[Dhadley]

Re: spark plugs

Be real careful when switching to a brand other than what the OE recommends, another brand isn't always the exact same heat range even though they cross on a chart. NGKs are an excellent brand but sometimes the crossover tends to run hotter than what the motor is calibrated for. If you do use something other than the OE recommendation, Champion in this case, be sure to go thru the procedure for checking for a lean burn condition.

We've always used the (Q)L77JC4 in a crossflow like these mentioned. Especially with todays fuel.

 

[huron]

Re: spark plugs

Thanks for the reminder. The L77JC4 are what was in it when I got the motor back from the rebuild. With those it idle nice and smooth. I have been running the QL16V, top end is fine but it idles really rough. From looking at the plugs it was a lean idle (tan & wet). Motor would sneeze alot and sometimes just die. Cold starts I would have to hold choke in until it would stay running. By the way, the NGK cross overs caused a 1500 rpm loss. They were also, almost 1/4" shorter. I'll stick to Champs. Anyway, thanks for the numbers, I just couldn't remember those L77JC4.

 

[huron]

Re: spark plugs

Thanks, same reply as to Dhadley.