michigan prop ID

[Autotech1]

Ive got a michigan (wheel?) prop stamped "SMC 378 CUP", Ive searched the internet and michigan wheel site and cant find abything, Id like to know what pitch this prop is so we could replace it. Were thinking 2 pitch sizes up tho, as were repowering.

 

[walleyehed]

Re: michigan prop ID

What drive unit or outboard are we looking at here....that might help me find it.....
Not a Volvo by chance, is it?

 

[Autotech1]

Re: michigan prop ID

Sorry, its a merc 260 #1 pre-alpha.

 

[Gammabusa]

Re: michigan prop ID

Dont know if you trust this ebay seller but he states following:

http://cgi.ebay.com/ebaymotors/MERC...2891204QQihZ017QQcategoryZ26456QQcmdZViewItem

YOU ARE LOOKING AT A USED MICHIGAN ALUMINUM 15 1/2 X 19 PROP. THE ONLY NO. I FIND ON IT ARE SMC 378 I DID TAKE IT UP TO MY DEALER AND HE CALLED MICHIGAN AND THEY CAME UP WITH THE PITCH FROM THE NO. ON IT IT HAS A DIA. OF 15.5 INCHS AND THE PITCH IS 19 IT CAME OFF A 1981 FOURWINNS 204 WITH A 228 H.P. V-8 IT HAD A 1.5 RATIO DRIVE LETS TALK CONDITION I WOULD RATE IT A 8 OUT OF 10 THAT IS A 10 BEING NEW THIS IS A USED PROP. THAT IS OVER ALL GOOD LOOKING

...Ronny

 

[walleyehed]

Re: michigan prop ID

MWC P/N=031037....merc P/N (OLD)=79574A 4, New P/N=48-11324A45, 15-1/2X19C (cupped).

 

[Autotech1]

Re: michigan prop ID

Thanks guys.

so going to a SS prop, would u keep the cup, were wanting to up the pitch a couple of inches as were repowering for more torque and HP? 20" or 21" P.

 

[walleyehed]

Re: michigan prop ID

A non-cupped prop is almost a thing of the past on a hull that planes...
As for going up in pitch, how much HP are you adding?

 

[Autotech1]

Re: michigan prop ID

not sure, the motors at least 350hp with the holley 650, but were putting the marine q-jet on and the merc manifolds are likely more restrictive than the headers that were on it. were gonna take it easy with the throttle tho, and swap to an alpha1 lower when we can.

Weve never dyno'd this motor but its a torquer for sure. 0 to 60 in the suburban was pretty quick.

 

[walleyehed]

Re: michigan prop ID

Well, if you swap lower units, you'll likely have a different gear ratio, so it may not be the same prop.
As for running 350HP with the pre-alpha lower, you probably better stay close to shore.
At 17HP required per mph gain, you'll be looking (in theory) at 5.3mph gain for adding 90HP.
If you figure in the additional lift of the boat, maybe 2 more mph.
Although I don't believe that lower unit will handle that HP, the 21P won't be far off, possibly a 22P depending on what RPM you're looking at.

 

[Autotech1]

Re: michigan prop ID

Is the reduction in the lower or upper unit? I figured wed keep it around 4400 or 4500 rpm and just prop it accordingly, altho the motor could do 6 easily (short intervals) we shifted this motor at ~6500 when it was in our 68 Nova. We won the Quick street championship with this motor (with a bigger camshaft). Its balanced for high revs.

 

[walleyehed]

Re: michigan prop ID

There is the top reduction and the botom, which is referred to as the "final" reduction or propshaft gear ratio.