1978 Johnson Stinger 75 hp prop help

[bbroskey]

ok, I recently took my old prop to two boat shops to see if they could tell me what pitch and size it was. Neither one could tell me much about the prop except it was a J 80, which he said was an old prop number. Can anyone help with finding out the pitch of this prop ?

 

[ledgefinder]

Re: 1978 Johnson Stinger 75 hp prop help

Try looking closer, sounds like it MIGHT be a PJ80, which is a real common Michigan 17" pitch prop that fits your motor (the OMC triples) and the OMC V4s.

 

[ledgefinder]

Re: 1978 Johnson Stinger 75 hp prop help

By the way, DON'T let that 75hp lug. That's a real highly-tuned engine (75hp from 50 cubic inches) to be running on today's gasolines. Prop it so that it spins around 6000 rpm with you alone in the boat.

 

[bbroskey]

Re: 1978 Johnson Stinger 75 hp prop help

ledgefinder,<br /> I recently bought a used 3 1/4x17 used prop and the boat has alot of trouble getting out of the water with just me in the boat.<br /><br />The other problem is that I don't have a tach. So I can't tell what RPM's it is running at.

 

[ledgefinder]

Re: 1978 Johnson Stinger 75 hp prop help

Sounds like you've got a couple 17" pitch props. That motor should be able to push a 16' boat OK with the 17". Do you think the motor's healthy (compression checked, clean carbs, good ignition)? Is the hull possibly water-logged? I'd be careful about running it at sustained full-throttle the way it is. It's clearly lugging & may be running lean - bad combination.

 

[bbroskey]

Re: 1978 Johnson Stinger 75 hp prop help

What do you meen by "hull being water logged" ?

 

[ledgefinder]

Re: 1978 Johnson Stinger 75 hp prop help

Fiberglass boat hulls can take on water in their foam floation, and subfloor bilges, gaining several hundred pounds.

 

[Hooty]

Re: 1978 Johnson Stinger 75 hp prop help

Also, as was mentioned in your other posting, you really do need a tachometer.<br /><br />c/6<br /><br />hooty

 

[Chinewalker]

Re: 1978 Johnson Stinger 75 hp prop help

I have my Stinger 75 tached out at about 5800 revs using a 17-pitch on my 15-footer. As you can see, she hums right along...<br />

<br />- Scott

 

[bbroskey]

Re: 1978 Johnson Stinger 75 hp prop help

ledgefinder,<br /><br />How can you tell if it is water logged and if so is there a fix ? I can still pull the boat up to my truck by hand and it doesn't seem to be any heavier.