changing prop

[steveo32]

I have a 1975 70 hp Johnson outboard, 13 spline thru hub exhaust.

I plan on changing the Prop this one is a little banged up but I will keep it as a spare.

I have referenced the parts catalog and determined that 13 1/4" x 17" pitch is the stock replacement and have found the cheapest one to be at this link



not sure if the link worked or not but it is a Michigan Wheel Vortex XHS
Prop: 992104 Hub: 106.

My question is do I need the hub kit and is it supplied or just listed for reference. And also will this 106 hub kit work, I have checked other sites that indicate hub kit 101 and 111 for my outboard.

Also on another not I would like to get some spark plugs too, preferably NGK brand but Champion will work too. What or How do I find what kind of plugs I need. Have searched google with no luck.

Thanks

 

[tashasdaddy]

Re: changing prop

your motor was designed to run on champion plugs, here's a chart to bookmark
http://www.boatsetup.com/SparkPlugChart.pdf

also check here for your prop. i perfer OEM props. http://www.boat-props.com/propeller...nson&horsepower=&year=&rotation=Both&x=43&y=7

 

[5150abf]

Re: changing prop

I was told by a marine mechanic that you can actually damage the ignition using anything other than the Champion plug designated for your particular motor, don't know if he is right or not but I am not going to take the chance either.

 

[Dhadley]

Re: changing prop

A "mechanic" said that, huh? Interesting. Using the wrong spark plug will damage a piston, not the ignition.

 

[steveo32]

Re: changing prop

thanks for the response guys, I was also wndering on the pitch of the Prop, My boat is a 15' tri hull with 70 hp outboard. I believe the total weight of the boat, motor and gear is at the most 1100lbs. The link you gave doesn't tell me the pitch, I found in the BRP catalog that 17" is the oem pitch does this sound right. Anyone have a simialar setup if so what pitch are you running, I believe the larger the pitch the lower the WOT rpm and the smaller the pitch the greater the WOT rpm.

Thanks

 

[Rudy Brown]

Re: changing prop

Pitch on the prop sounds about right. That is what my late Father-in-law ran on his tri-hull boat with a '75 70hp. Run champion plugs in that motor, nothing else, and Dhadley is the man. If he tells you something, take it to the bank.