Info on 1970 's 50hp Mercury Racing prop required.

**Old boy** · 06-25-2017, 07:16 PM

Hi,
My good friend John commenced racing boats in Australia in about 1965. In 1974 he built and raced raced a 12' timber light weight mono hull. It was powered by a 1974 short shaft, rope pull 50hp Mercury (std gear case etc). That boat managed to run a pretty solid 58 mph in race trim and won many championships in the 70's years. The motor was quite high, having the centre line of the prop shaft about an inch or so below the bottom surface of the transom. I recall his prop was a Mercury product, being stainless steel, 3 blades and no tube. From memory, the prop was a rather high rake prop, and looked a little similar to Mercury's current Chopper II.

Neither of us can 100% recall the diameter nor the pitch of this sensational Mercury prop and we would be grateful to receive any information that we can, as we are looking to purchase one if possible. (we are reasonably sure it was 22'' pitch)

John is now 71 yeas young and he is about to return to boat racing in the "antique/classic class". He tells me, he's antique and the motor is classic!
He has recently put together a older fibreglass 13 foot hull from the '70s with a "Classic 50" Merc clamped to the back. With only a 22" tubed cleaver available at present, John went for trial runs up and down the river yesterday and this boat is sitting a little too flat, despite adjusting the tilt pin position. We are pretty sure we need a prop with more rake.

We are both very eager to obtain photos of the prop we use to run in the '70s or better still, purchase one via S&F.
Any information on the old race prop from the 70's will be greatly appreciated.

Many thanks.

**Mark75H** · 06-25-2017, 08:09 PM

One of the rarest props out there. You may never find one for sale.

**Old boy** · 06-25-2017, 08:37 PM

That's not very good news.. Do you recall the name of the prop we are chasing down? I seem to recall the name Elephant Ear was used.. or was that another prop name?
Perhaps we should be looking at what the Thunder Cat boys have for sale? I recall they run Cleavers and Choppers as well.
All advice is most welcome.
Thank you.

**Mark75H** · 06-25-2017, 09:06 PM

"Special 3 blade high rake cupped factory prop for 500" There was no special name, but its a special prop. Might be able to find the part number for it somewhere.

**Old boy** · 06-26-2017, 12:03 AM

This is interesting... I've just found on two separate websites the gear ratio of the Classic 50 is in fact showing as 1.83:1
The Tacho wasn't working during our initial run and a new one will be fitted prior the next run.
In 1974 etc the 4 cyl Merc 500 had a gear ratio of 2.0:1 I recall. Perhaps the 22" prop we are currently running has too much pitch for that particular ratio?

**Old boy** · 06-26-2017, 02:08 AM

I think I must clarify something here.. my friends motor is a genuine 1987 "Classic 50", having 45hp at the prop.

**2us70** · 06-26-2017, 10:35 AM

In 1974 and75 I ran a similar motor on my McCall in SD class. The prop I had the best luck with was a 12x20 with a fabricated exhaust tube. I also ran a 12x22 prop on this boat without an exhaust tube with some success. In the early 70s the lower unit gear cases on the 50s were the same as the 65s but with different gear ratios. My propellers for this boat were originally from my E production boat with a Merc 650 on it. I have no experience with the later model 44ci motors. It is my understanding that they have different ignition and carburation as well as lower unit ratios. The original Merc 500s had much higher gear ratio lower and ran could only run much smaller diameter and lower pitch props.

**crazy horse** · 06-26-2017, 05:08 PM

The props your looking for are 11x22 3 blade A-48-61882 and 11x24 3 blade A-48-61886. These numbers are from a 1974 Merc catalog They are for a Merc 500 with 2:1 gears. I had a 2 blade 11x22 that I sold to a guy up in the U.P. of Michigan. It was from a 73 merc with 2:1 gears I had it on a old class D runabout, That thing was fun. Three blade props from that era are VERY rare. I had one for my Viper back then and cracked it a couple of times. They had very thin blades and small hubs so it didn't take a lot of hard running to crack one.

**2us70** · 06-26-2017, 06:02 PM

If you are running less than 2:1 lower unit gearing you will be hard pressed to find a performance prop for that motor. Also the cleaver props didn't seem to work very well on runabout hulls for me. We ran one on a little tunnel boat and it worked ok. crazy horse has jogged my memory. My exhaust tube fitted prop was an 11X20. Turned a bunch of revs. The older 50s pretty much ran reworked Mercury bronze props. The best one of those I ever had was one olegator did for me a couple of times

**Old boy** · 06-27-2017, 09:30 PM

Thank you to all who have contributed thus far.
11x22 3 blade A-48-61882 is really ringing a big bell with me! I'm betting that what my friend ran in the 70's.
Does anyone have any suggestions what we should purchase seeing that blade is now as scarce as hens teeth?

Does anyone have an old photo of their boat with a that prop on it?

**2us70** · 06-28-2017, 10:11 AM

I borrowed one of those 3 blade props from the factory truck at nationals. I could not get it to work. The extra bite bogged down my motor and the tail lift bogged down the boat. Here is what a 74 500 W/2blade 11x20 with exhaust tube looks like when you get it right.