Name this lower unit

[Mark75H]

We found the limiting factor on the McCulloch's to be props. The motors had the stuff and the lower unit was OK, but props for them just weren't there.

[smokin'joe]

Well, I think you could say the same about all the stock props of that era, including those for Mercury and OMC. I tried to repitch a bronze Merc 500 prop last fall, could not really do it right. Those props had a profile like an airfoil, so leading edge pitch is hard to set because they were inherently cambered wrong on the suction side. We couldn't run more than 61 mph with a Merc 800/Sportsmaster on the 13' Allison in 1960 precisely because we were prop-limited. Modern surfacing props have a relatively flat suction side (if you imagine hammering out the camber), so it's easy to set the pitch at the leading edge using a gauge that reads pitch 3/4-1" chords, like the Rundquist gauge. I remember having an OJ racing prop for my standard gearcase Mark 30, that blade profile wasn't any better.

Now that I've said that, how did a Merc 500 run 50 mph in 1961-? Actually, i don't know what props they had in '61, I quit in 1960.

[Mark75H]

Merc and Michigan sold 17's for them (48-32176-A1 and AJC484). 1.64 gear ratio, 8% slip= 54 mph @5,500 rpm

[smokin'joe]

Merc and Michigan sold 17's for them (48-32176-A1 and AJC484). 1.64 gear ratio, 8% slip= 54 mph @5,500 rpm

Scott 75 with which gearcase? I don't have numbers on Scotts. By the way, if you know the c.i. displ. and gear ratio of the 1959 25, I'd appreciate knowing it. Thanks.

[Mark75H]

The 1959 25 hp Scott is 30ci.

Plenty of slow props for the std McCulloch gearcase ... the fastest prop we had could only go 50 or so and the motor was seriously over revving on our little Glastron (or maybe it was a cheesy Sportcraft copy of a Glastron). We never ran a 75 Custom on the same boat, but the props we had for the Custom units went well into the 50's without over revving the motor. We only found the one prop for the Custom and I think Michigan only made 2, one for single engines and one for twins.

[smokin'joe]

The 1959 25 hp Scott is 30ci.

Plenty of slow props for the std McCulloch gearcase ... the fastest prop we had could only go 50 or so and the motor was seriously over revving on our little Glastron (or maybe it was a cheesy Sportcraft copy of a Glastron). We never ran a 75 Custom on the same boat, but the props we had for the Custom units went well into the 50's without over revving the motor. We only found the one prop for the Custom and I think Michigan only made 2, one for single engines and one for twins.

How many RPM? What's upper safe RPM with 25:1 oil?

[Mark75H]

I don't know much about that motor, its bore and stroke are not common to its sisters in the line up. Probably 5500 rpm, most were big bores

[smokin'joe]

Quite unassuming. Easily mistaken for a 50hp lower unit.

Maybe Eric can supply a better picture...

Can I get permission to use the picture of the Sportsmaster gearcase in an
AOMCI article?

[smokin'joe]

Joe, you are correct, 1960 is the first year the Speedmaster was legal. The first spec sheet I have showing them is dated Jan 1, 1960. I had the spec sheet and never looked at it. You made me go back and do thorough complete research to learn that date.

At the same time the left and right 800 Speedmasters came out, so did the one in this thread ... not an 800 but a 700. There were subtle differences between the two and that is what this thread is about. 80hp Speedmasters used 3/4" smooth propshaft with 5/16 shear pins, this one has a 1/4 hole, so it was for a 70hp.

Info on the Sportmaster lower unit is in this post: http://forums.screamandfly.com/forum...1&postcount=24

We got 1 or 2 Sprtsmasters, either McCall's Marine or Blake Cox may have gotten another because Paul Allison did not own the one that he drove in the 1960 NOA time trials. For the time trials Paul'd swapped his fat 75 for Blake's Merc 800, and ran an Allison that had McCall's Marine written on it, I think. McCall was a Knoxville Mercury dealer. To be honest, I don't know if more than those 2-3 Sportsmasters were produced. Anyone have any info?

[smokin'joe]

Yep, I Thought That Was Us.

Jim. Your photo-you've changed! You were wearing an Evinrude cap in '79.

[Mark75H]

To be honest, I don't know if more than those 2-3 Sportsmasters were produced. Anyone have any info?

I've seen about a dozen, but I've heard from a reliable source, that the number was not hundreds. Certainly more than 2 or 3. Probably at least 50 or 100. It was intended to be a production item like the Speedmaster.

You may use my pictures, please credit the one without paint to Rick Connolly

[smokin'joe]

Now I remember seeing one at a Mercury dealer near New Haven, Conn., in 1965. And, NOA must have had many Sportsmaster units running in 1961.

First time I saw a Speedmaster unit was outside New Haven in '65, had gone there to grad school. A young black guy had stopped by the road with a Powercat, I think, and two Speedmasters. Had been on the river to test.

[wuhbbr]

it's a 1953 Hudson Hornet lower unit

[Mark75H]

it's a 1953 Hudson Hornet lower unit

Hopefully a moderater will delete this comment

[wuhbbr]

Sorry if I offended you. It's a joke !!
Which means I haven't a clue what Merc it fits.
Carl Keikiefer (sp) raced Hudson's at Daytona in the 50's and won.
My Dad had a Hudson and made a truck out of it.