1958 Johnson Seahorse 10HP QD-19

[Jellio]

Hello,

First time poster here....quick question I've been doing some searching and trying to determine the correct spark plug for this motor. The previous owner is running J8C but I've read J6C is the way to go...can someone tell me which one to run and at what gap. Also will I be okay to run it 32:1 mix on the gas/oil mixture I've seen both 24:1 and 32:1 and some even say 50:1 I don't think I'd ever run it that lean and the previous owner has 3oz/1 gallon of gas which is closer to 40:1.

Thanks for the input in advance.

Jellio

 

[samo_ott]

Re: 1958 Johnson Seahorse 10HP QD-19

Hey... Welcome to the iboats forum. I have a few of those engines, great engines but a weaker and error prone lower end. J6C is the correct plugs but the 8's are hotter and better if you troll a lot I hear (I don't troll) and all the plugs are .030" although, again some say, if you troll a lot making it .040" helps them to foul less.

And the official mixture from OMC was 24:1 although some folks make a tad leaner. I myself, use 30:1 for all my old engines. and I use fully synthetic pennzoil form walmart.

 

[JB]

Re: 1958 Johnson Seahorse 10HP QD-19

The original spec was for J4J (now J4C), jellio. It was later changed to J6C because of the J4 tendency to foul when trolled for long periods. The gap spec changes back and forth between .030" and .040".

I would use the J4C for high speed use and the J6C for trolling. Either gapped at .030". Under no circumstances would I use a lawnmower plug (J8C). It is just too hot.

The current spec for fuel mix is either 20:1 or 24:1. There is no sanction that I know of from OMC or BRP to go any leaner than 24:1 on a '58 model.

 

[Jellio]

Re: 1958 Johnson Seahorse 10HP QD-19

Thanks for the replies guys...I'm going to go with the J6C and gap at .035 to start with. Today I tore into the lower end to change the impeller. I ordered the replacement from Napa should be here tomorrow. After I made the order I pulled it apart expecting to find a mess but to my suprise the impeller was brand new. I will keep the new one for a back up. I also ordered new coils and the electrical tune up kit from Napa prior to looking and when I looked in the inspection hole of the fly wheel all the parts have been recently replaced...no cracks in coils and everything looks like show room new. I'll have back up parts for that now as well.

For anyone else thats a newbie like me the impeller fins need to be bent backwards in the housing to get it to fit.

She's about ready to pppppuuurrrr hopefully.

 

[Outdoorant]

Howdy from Colorado, I'm Outdoorant and I'm trying to bring a 1958 QD-19 10 hp back to life. It is in fantastic condition considering it's 60 years old. May I please ask directions to a link, or a schematic, or manual, and also a how to and where to get parts... I have had small success at NAPA, but not alot because I need the part numbers and identifiers. ANY input would be greatly considered... Please and Thank You... Outdoorant

 

[Outdoorant]

I have had it running for brief periods. Did the standard clean and flush... The initial settings on the low speed jet I started at about 1.75 turns out. While adjusting the high speed jet she quit sparking on me. The volt packs look shot, I'm pulling the cover tomorrow. Any info or prayers gladly welcome ...lol.. Outdoorant

 

[F_R]

The moderators probably will put this 8 year old thread back in the archives.

 

[Willyclay]

May I please ask directions to a link, or a schematic, or manual, and also a how to and where to get parts...

http://boatinfo.no/lib/johnson/manuals/1922-1964johnson.html#/0

 

[GA_Boater]

The moderators probably will put this 8 year old thread back in the archives.

Yes.

Outdoorant Please start a new thread.