Merc Speedmaster

[mercmack]

MERC SPEEDMASTER, CLEAN LOOKING WITH PROP ON E-BAY
no 180064907175:) :)

[Mark75H]

Correctly described as a 1962-64 100 hp type Speedmaster. # 274 would probably make it a 62, but I really haven't seen numbers a lot higher.

Pretty cool to look at, but hard to use for most boats. Lowest common prop pitch is 15 ... for boats that can run well over 75 mph. The prop it comes with is a 16. Speed increase over a stock lower unit is only about 3 to 5 mph, so don't fool yourself into thinking your rig can pull the 16 if you aren't already running almost 80.

The reason props are so high pitched for the Speedmasters is almost all race boats using 6 cylinders and Speedmasters were twin engine rigs. The few single engine rigs using Speedmasters were super light weight full race boats with TOTAL rig weight less than 600 pounds.

[Droll-l6]

Just checked the # on the propeller.
#48-30073 came back as Left hand rotation 16" pitch 2 blade SS propeller .

Then this Lu might be a left hand rotation unit ??? , what engines could use this unit, the old dockbusters ?? running backward ??, or could they do that over time ? .

Just curious :)

Arne Kjetil

[Mark75H]

I was wrong, this unit was made for the 1961 80 hp Merc (Dockbuster).



It is a left hand rotation unit, the motor still turns cockwise, the rotation is changed by the position of the gear on the prop shaft.

The features that are specific to this unit are the 8 spline driveshaft and the water inlet on the body very close to the skeg. Right hand units for this motor had the water inlet a little farther forward but still on the housing and not the nose cone. The 1961 70 hp Speedmasters used a smaller driveshaft.

[Mark75H]

The 1961 Merc 80 dockbuster tower is shorter in front of the driveshaft than the gear shift towers because the shifter rod runs down the front of the shift units; and the 61 dockbuster is longer from the driveshaft to the back bolt than previous dockbuster towers with the change to thru prop exhaust on the standard lower unit.

This particular Speedmaster is the only style that only cleanly fits one tower.

[Droll-l6]

I was wrong, this unit was made for the 1961 80 hp Merc (Dockbuster).
It is a left hand rotation unit, the motor still turns cockwise, the rotation is changed by the position of the gear on the prop shaft.

The features that are specific to this unit are the 8 spline driveshaft and the water inlet on the body very close to the skeg. Right hand units for this motor had the water inlet a little farther forward but still on the housing and not the nose cone. The 1961 70 hp Speedmasters used a smaller driveshaft.

Got a friend looking on this unit, want to use it on his 76 ci L6 engine ( that's all I know )

From my books, his 76 ci engine could be ( I don't know witch on, but suspect it could be the 850 ):

1960 800 DR
1961 800 DR or gear shift
1962 850

So i would work on these engines ???

Arne Kjetil

[Mark75H]

Only the 61 Dockbuster.

There are 3 different housings on the 76ci motors.

The mid of the gearshift housings will hang out in front of the Speedmaster (I'm not sure the front stud will match up at all), the Speedmaster will stick out longer than the 1960 DB at the back.

[Droll-l6]

Tobad it didn't fit his engine, but atleast he saved some money :) .

Found 4 different model# for the Speedmaster :
1624-1870A3 for the Merc 700
1624-2028A3 for the Merc 700
1624-1870A2 for the Merc 800
1624-2028A3 for the Merc 800

The difference looks like it's the drive shafts ( 2 types) + housing ( 2 types) = different combinations of those ...

Arne Kjetil

[Mark75H]

The differences between them is the driveshaft size and the rotation, that group all fit the 1961 Dockbuster tower. The housings are different between right hand and left hand rotation.

The next one fit the 1962 & later full gear shift tower. The 1962 Speedmaster housing took internals for both rotations. In 1965 Merc came out with the dual driveshaft/pinion SUPER Speedmaster that also fits the full gear shift tower. Minor variations of the Super Speedmaster were produced until the mid 1970's.

[largecar91]

I hate when they do the hidden bidder stuff. We can't see who's winning. It takes the drama out of it!:D

[alan akerstrom]

I have a set if 13/16 NOS gears that I think would fit this LH speedmaster. That would make the normally available high pitched speedmaster propellers work better for a single engine application. Someone should trade me a set of NOS merc D gears for them...

[Mark75H]

Allan, I'm not sure Super Speedmaster gears will work in a single pinion Speedmaster. Have you held both in your hands and compared them?

[Ray Lumpkin]

Mark 75 is just about right. I raced this unit on a 1960 800Dr Merc engine. I had right and left hand units. Also had 1to1 and 14-15 gear ratios. Use for long and short courses. Top speed on new 14 foot McCall tunnel boat was about 75 at best. I think I used mostly 15 inch 2 blade props. The unit would not stand much more than 80 hp. I blew several on the 800. I have an 800 I am restoring now with the speedmaster unit. I set the 5 mile world record with this rig in 1974.

[alan akerstrom]

I thought these were from a 650/700xs speedmaster. Sam- Should I send these to you with return postage for identification?
Did the insert photo utility change? I can't figure it out tonight...

[Mark75H]

The BRF image attachment software is broken. I think vBulletin will have to be reloaded to get it going again, so we are stalled for a few days.

13/16 650x/700x gears fit in the 1965 and later Super cases and I'm not sure they fit on the pre-Super shafts. Just send the pictures to me at Mark75H@comcast.net

[Mark75H]

Thanks to pictures Allan emailed me I can confirm that the prop shaft gears are different in Speedmasters and Super Speedmasters. Speedmaster prop shaft gears have 6 splines and Super Speedmaster prop shaft gears have 11 splines.

[Roy Hodges]

Tell us about the Mark 75 H lower unit. Please . LON STEVENS told me about 30 years ago it was his FAVORITE
for 6 cylinder Mercs ( 60 & 66 cubic inch) . I understand they were VERY rare ?

[Mark75H]

There were about 80 or 90 Mark75H lower units made and most of them are still around. They are a unique piece because the lower unit only fits the Mark75H mid section, it will not bolt up to anything else. The split between the mid and foot is thru the middle of the exhaust outlet, half on the bottom, half on the top. This also puts the steering swivel bosses one each on the separate parts, unlike any other racing lower unit and tower. The 75H mid and foot end up being about a half an inch deeper than a Mark 55H tower ... about 15 1/2 inches from the clamp to the center of the prop shaft. A Quincy tower and Speedmaster are normally about an inch longer at 16 1/4 or so ... not exactly the same as a 75H. The 75H stuff fits on a regular 55H swivel, uses a 55H copilot friction disk, etc. The propshaft and propshaft gear were exactly carried over to the first type Speedmaster, but the driveshaft is special. The pinion gear teeth and outer diameter are exactly like the early Speedmaster .... but the splines on the end of the driveshaft are smaller like a 55H driveshaft, so a Speedmaster driveshaft gear won't work as a replacement. The water pump housing is unique to the 75H, too. Water enters the housing from the bottom front, not like the std pump body where the water enters from the top back via an external tube ... but it is a dual rotation Dockbuster check valve type pump. The Speedmaster pump also feeds water from the bottom front, but is is skinnier to fit in the FGS tower, the 75H water pump housing is more of a box.

Some pretty good pictures on Charlie Williams' site: link to www.outboardracing.com (http://www.outboardracing.com/merc6cyl.htm)

http://www.outboardracing.com/images/image32.jpg

[largecar91]

Here's a 75H with a speedie.

[Mark75H]

Thats the only way they were made. The Speedmaster looking part does not come off of this set up, it is intergral

[largecar91]

I Will Post Some Pics Of The Whole Motor When It Is All Back Together.

[Mark75H]

Cool! I don't remember if I've asked you how original the powerhead is; whether it is an original 75H powerhead or just a 60ci?

[largecar91]

Got 2 of them. One is original and the other is a Quincy powerhead. I will have to get some pics. Not really sure what"s in the Quincy for sure. Also have a real neat mid and lower for the Quincy.

[curbman]

I Will Post Some Pics Of The Whole Motor When It Is All Back Together.


Has the engine been finished, hope to see the pictures.

[largecar91]

I think if I had 40 hour days, I could still not everything finished! Racing and life seems to get in my way!.

[curbman]

If we could stop time and then catch up we would be in the shop for years. Good luck on finding the time to work on your project we would all love to see it come together for you.

I think if I had 40 hour days, I could still not everything finished! Racing and life seems to get in my way!.