1956 Johnson Rehab project starting question

[bonito1]

Hi Everyone.

I am starting on an outboard rehab project with a 1956 Johnson 15hp - model # FD-10 L. I know the motor is cool as hell. Unfortunately that is about all I know right now! I bought it at an estate sale and hope to get rolling right away. My first plan is to build a stand to have a base to work from-I am heading to Menards for those materials now. Next I will test for compression and spark. So my first two questions are:

1-what do you think a good compression reading will be? 60ish and even on both cylinders?
2-How do I test for spark? And should I get new plugs to test for spark?

Oh yeah. Apparently I need a pressurized gas tank. Should I get one now, or convert to a single line non pressurized fuel system right away? I guess I don't want to convert to a new system without knowing if she'll run, but I also don't want to invest in a pressurized system and learn that it won't run. What would you do? What is a good source for either system?

Any other suggestions for things I should do to get started?

Thanks all! I look forward to any help and will post progress as well as other questions as I move along.

Bill

 

[HighTrim]

Re: 1956 Johnson Rehab project starting question

Great buy. I love those motors.

To start, you will need a manual. If you PM me your email address I can help. Price is right, free.

Second thing you will want to do is check compression. Main thing is they are even, the reading will vary by gauge used, but you will definately want more than 60psi and even on both. You will hopefully be a bit higher than 60. If compression is good, then and only then should you cary on.

To test for spark, you will need an adjustable air gap tester. These are cheap, yet necessary. Probably around $10. Remove a lead, insert it on the end of the tester, set the tester to 3/8", ground the tester with the clip to the powerhead, preferrably somewhere without paint, then pull the motor over. You should see a blue spark with a real ZAP!! If not, start by checking the coils, if the are original they will need to be replaced. But dont want to overload you with magneto ignition troubleshooting right away.

Start with compression, test the spark, then let us know what you find.

I personally like the pressure tanks, but alot of guys convert to the single line tanks. Check the FAQ for info. For tanks, go to aomci.org, and post a wanted ad in the webvertize section. Or go to a meet, you will get plenty of free advice, and cheap parts. Just make sure the tank is clean inside of rust and varnish. Rebuild kits for them are available on ebay.

Keep us updated.

 

[steelespike]

Re: 1956 Johnson Rehab project starting question

100 psi and even would be excellent it will run at 60. A spark tester from an auto supply would be good but I usually try to rest the plug on a bare spot and crank with both plugs out.
Look for a strong blue audible spark.If the coils haven't been replaced it will need it.
Cracked or discolored coils need replacing.Routine parts are readily available.

 

[kfa4303]

Re: 1956 Johnson Rehab project starting question

Check out these links too.

http://forums.iboats.com/showthread.php?t=158086

http://www.duckworksmagazine.com/07/columns/max/index1.htm

 

[Steve A W]

Re: 1956 Johnson Rehab project starting question

Bonito
Last month I picked up a used presure tank with fitting for $45
at an AOMCI meet.

http://www.aomci.org/index.htm

There are those that claim they are dangerous, But no one has
provided evidence of one blowing up.
Take care of it and prevent rust and Your good to go.
Steve A W

 

[bonito1]

Re: 1956 Johnson Rehab project starting question

Thank you everyone for the replies. Very helpful already!

I got my stand built and fixed up a spark plug cable that High Trim helped me with. Hooked up my trusty $9 compression guage and let her rip. Unfortunately the recoil starter appears to have a hitch in its giddy up. It only seems to partially engage and does not recoil fully. For the engagement it did have, I only got 30 PSI! AAUGGH! I THINK this might just be the problem with the recoil starter, but am not entirely sure of course.

So, here's my next question: Any way to test compression with a bad recoil starter or do I need to replace it before really knowing the compression. The motor id sound good with a nice healthy huffing sound but that was it.

Any ideas?

Thanks, Bill

 

[kfa4303]

Re: 1956 Johnson Rehab project starting question

hi bonito1. there are a few tricks you may want to try. the easiest is probably to remove the recoil starter assembly and use a drill with the correct sized socket on it to engage the flywheel nut. you can then rotate the flywheel CLOCKWISE ONLY at a speed roughly the same as the pull start would to test the compression. just be sure that you only ever go clockwise. you may also want to spray a liberal amount of WD-40 or Seafoam into the cylinders and let it sit overnight, then give it another try just to hlep loosen things up a bit. your compression numbers may actually go up once the motor is up and running too, so if you can get +60psi per cylinder by using the pull start or drill method it's probably worth your trouble. however, if the two cylinders are more than 10% different in their compression numbers you may have a headgasket issue. they're pretty easy to fis even if that is the case though. lots of posts here in the forums that can help with that sort of thing. hope it helps. keep us posted.