14 tooth non exaust hub pin drive

[catfishcarl99]

i have a 17' spectrum fish and ski. might as well show it as pics tell alot more than words. its a double walk thru console. kind of heavy. here i'll just post em.

ok. you see the boat. and its a force 507y9b 1989 50hp. i got the thing all de bugged. its old needed a few things in electrical system to get it purring but it runs like a dream now. idles and doesnt die like it used to when brought from WOT to N. so changing up isnt really a need. but my Q is. i get 25mph out of it with just me. well that with a full 20 gal tank. and i have 2 batteries. a start and troll about the same size and weight standard. troller is same dimentions as starter. not a huge one. with just a little gas i did get 29 out of it. with me and cuz in it 21-22. i have a plane wing on motor. no power trim. has the pull out pin style. i usually run it on outer most hole. any more in slows it by placing more of the deep v in water.
it has the puny non exaust thru hub prop. common on these force and crysler engines. a 10 3/8" 11 1/2 pitch on it 14tooth pin drive. cast alum with press in hub. this is the same prop.

i got this one at a yard sale for $5. it had a different hub in it after i got it home so i fig i could get it re hubbed. but since i found one on ebay and got it for $40 shipped. brand new. there michigan match. my Q is, do i have any options to gain a lil more speed. seems about every 10 3/8 pitch i find on ebay are all pretty much the same but maybe in white,lol. is there any different pitch's that would gain me a lil speed? i mean i use it 90% as a fishing boat and i dont fish tourneys so i dont have to run 70mph to get a jump on anyone. just wondered if i had options. it seems like this was like buying a full sized ford extended cab 4x4 long bed with a v6. the boat is rated for up to 85hp.
changing to a bigger motor isnt a reality since it runs so good. an extra 5 mph would please me alot. just dont know if theres a way. im dumb when it comes to prop pitches VS power and speed. so please explain when making suggestions if you would. thanks.

 

[catfishcarl99]

Re: 14 tooth non exaust hub pin drive

few of the motor leg and setting i run on.

 

[catfishcarl99]

Re: 14 tooth non exaust hub pin drive

ok did some investigation on michigan wheel. i see they make 10 3/8"x 10 pitch 11 1/2 pitch 12 1/2 and 13 1/2 . so. what i have is a 11 1/2 pitch. means in 1 rotation it travels 11 1/2". so if i were to use a 13 1/2 pitch wouldn't that mean fatser???

ok this is the one i got from ebay.http://www.ebay.com/itm/180859801313 i talked to him about the shipping. said $48.50 was mistake. shipped for $12.10 but i sent him $15 since it was a $139.00 prop. i was tickled to death. says its a 12 1/2 pitch. so actually wouldnt that one make me increase speed a tad? im anxious to try that now.

the prop i got the 29mph out of is at the bottom of a lake. i had a worn clutch dog from slipping my boat in gear easy. the clicking into gear. i thought i was being easy on it when in fact i was wearing the corners off clutch dog. and it began to jump while in WOT. and the jump or bang it was doing was snapping my cotterpin on plastic prop nut allowing it to spin off. then when i would go to N the prop slipped off. a marine mechanic diagnosed it for me and i fixed it years ago. so i dont know what prop pitch it was. and i wound up loosing 3 props untill i figured it out. i had spun a prop hub before it all began happening and when i took it in to re hub it cracked the cast alum. so the guy ordered me a prop. i saved the part number and ordered those. but orig might have been a longer pitch.

but now i know what i have is 11 1/2 and the new (spare) is a 12 1/2. basically my Q now is that means faster??? or more power for skiing?? what way do i need to go to increase speed?

 

[catfishcarl99]

Re: 14 tooth non exaust hub pin drive

after some searching on the forum im also thinking about removing the hydro. this is oem engine on this boat. and the foil was not on it when i got the 29mph out of the boat so it may be slowing me down a mhp or 2.

 

[steelespike]

Re: 14 tooth non exaust hub pin drive

You need a tach so we can get your wot rpm and speed by gps if possible.
A Tinytach is about $47 and will fit any motor.Be sure you read all info before ordering.
Your motor needs to rev freely within it rpm band.
4750-5250.For best all around performance you should prop for the upper end of the band
lightly loaded,lower pitch prop.
If the motor falls out of the band at wot it will lug which can cause premature repair problems if it runs above the max at wot it can cause failure.
Don't misunderstand; you can control the rpm at any speed you like with the throttle but at wot it needs to be near the top of the band.
All that said as you increase pitch you lower rpm about 200 rpm per inch
and reduce power kind of like putting it in overdrive.
With the 50 your underpowered so it is very unlikely the higher pitch prop will work.
The foil is there to help the little motor out of the hole but likely is stealing some top end.
You can get it out of the hole other ways we'll a prop,trim tabs weight removal/placement.

 

[catfishcarl99]

Re: 14 tooth non exaust hub pin drive

so a lower pitch prop gains rpm and top end then? like the 10 pitch? makes sense as it would spin faster pulling less water. so the 12.5 will decrease the rpm and speed? and yes after reading some other threads ive already started a thread in force area about a tach. i do have a tach terminal on the motor wiring harness terminal. i figuered since most replies in other threads were asking about rpm's that it was something good to know. as over reving engine is not something you want to do.

 

[catfishcarl99]

Re: 14 tooth non exaust hub pin drive

ok i was wrong in my last post. a 10 pitch vs a 13 1/2 would be slower but get me out of hole better higher rpms. reading up have i. lol

ok. good and bad news. i have taken the prop off my boat. the one i got off ebay is indeed stamped 072132 12 1/2 pitch like he said.

bad news. after scraping off a bit of coating to read the stamp on existing prop. 072133. 13 1/2 pitch. the highest pitch for top end. so theres no going higher for top end.

now, i think i understand you now. beings im on the low end of HP with the 50 your saying it may be bogging me down thus a lower pitch may actually get me a little more speed and bring up rpms 200ish since it pushing a heavy boat. right?

basically if this 50 was on a 14' john boat bare bones the 13 1/2 pitch would top end the best but on a heavier boat may not as its lugging motor? think that kind of what im understanding.

well i know at one time i hit 29 mph right after i got it (also pre hydro-foil) and the orig prop that done it is at the bottom of the lake. so no idea what its pitch was. possible when i ordered new one he or i suggested the fastest prop and went to higher pitch. i dont know or remember. and now it does everything on a calm day smooth water to get 23. -6mph. so the foil came off today. one of them (young things) bought it in 04 when i got the boat thinking it would speed me up lol. prob dragging it down in reality beings it at the bottom end of rated HP. and im gonna try the 12 1/2 pitch next trip out and see what it does for me since it will up rpms. prob tomorrow. wanted to go today but didnt.

i also have a 11 1/2 pitch but its got a smooth hub. no splines. the shear pin may hold it long enough to test out speeds as well. then whatever suits me best i can use. but would have to re hub or get a 14 tooth 11 1/2. if it happens to be the best pitch tune for the motor on this boat.

 

[steelespike]

Re: 14 tooth non exaust hub pin drive

If the the 11 1/2 prop fits the shaft as it should the pin will drive it. Pin drive has been used on motors bigger than yours.

 

[catfishcarl99]

Re: 14 tooth non exaust hub pin drive

well so much for the test today. raining and pouring. ya i took off the atwood foil. i am gonna go maybe tomorrow now. i am gonna run the 11.5 12.5 and trim it in as i change them to and see what prop gets the best result. with the one i had on it (13.5) it didnt seem to plane like it used to. i do believe it was to much pitch for the 50 on the boat. we'll see i guess. at least i got all but the 10 pitch to test. best i can tell from searching that about all the props for this boat michigan wheel makes.

thanks for the help.

 

[catfishcarl99]

Re: 14 tooth non exaust hub pin drive

ok. first thanks steelspike. what info you gave me was enough to get my brain boiling. finally got out yesterday to test a different pitch. i went to the other end of the 3 i had and used the smoothshaft prop 11.5 pitch. and i scrapped the foil too. and wow. the boggy 21-23 picked up to a 26-27 and shot out of the hole much better. just that 4-5 mph was a noticable and most welcome improvement. next trip i will see if the 12.5 improves or slows me up. i trimmed it in a bit to with the 11.5 with really not much difference. got 26mph still. me and a full 20 gal tank. now im gonna have to go to ebay and get a 10p to try out. the 13.5 down to the 10 im guessing roughly picks up 700rpm's. unfourtunatly i still need to replace the unused sonar guage with a tach too. engine didnt sound racey at all.

 

[catfishcarl99]

Re: 14 tooth non exaust hub pin drive

 

[steelespike]

Re: 14 tooth non exaust hub pin drive

Boy thats great! Nice to see progress.
I think your gear ratio is 2.00 so if I guess 10% slip at 26 mph your rpm is about 5300.
No problem as long as you don't pound it continually at 5300.
When you get your tach up and running it should tell better.But it appears now that a 10" will be too small.
And usually if your propped about right and decrease pitch you will lose speed.
Probably the 12.5 will be too much but you might try it to see if a light load produces a touch more speed.
Could be disappointing but nothing ventured nothing gained.
You can double check the ratio by pulling the plugs and counting the flywheel revolutions to one prop revolution.
Make marks so you can measure accurately. Should be two revolutions to one prop revolution.
could be a little less or a little more thus the need to measure accurately.
Could be less under 2 or more over 2. Thus the need to be able to measure accurately.

 

[catfishcarl99]

Re: 14 tooth non exaust hub pin drive

well another update. went out tonight and tried the 12.5 pitch. 124 mph. got the sweet spot.


lmao. just kidding obviously. 26. so no change from the 13.5. and kind of glad. as this was the NEW prop. i only paid $40 shipped for it new but it would have been a kicker if it had been slower. the 11.5 that got me 26-27 was the smooth shaft one. when i removed it the other day the pin was broke in two pices and the hole in the brass hub was slightly oblonged. i really want to try a 10 pitch now to see if i cant get the 28-29 i got the first outing in 04. but for now till i find a good deal on a 10 p ill stick with the 12.5. 13.5 as a spare in event i loose a blade during a weekend camping outing. the 11.5. wall decoration.

forgot to check ratio. ill try to remember to do that today when i get out of bed this afternoon lol.

 

[catfishcarl99]

Re: 14 tooth non exaust hub pin drive

and your were correct i believe. i had a chip in powder coat on one prop blade. i noted its location and watched as i turned fly wheel. which also had a chip in paint that i aligned with starter gear. i turned it once and didnt see the prop chip. another turn and the chip in prop was almost where it started. 2 to 1.

 

[steelespike]

Re: 14 tooth non exaust hub pin drive

Good.
I wonder if the smooth bore prop pin hole was elongated in the first place. Hard to believe a few runs would do that.
Perhaps the pin was undersized or sub par strength.Is the hole in the shaft elongated?
There are lots of bigger and older motors than yours with pin drive.