Speedmaster 4 application

[ttorg]

I recently bought what looks like a very good Speedmaster 4 with the intent on using it on my 1974 Merc 1500XS. This motor has a 'J' on the block that is supposed to indicate an XS powerhead and a louvered cowl.The front stud location will not fit my lower unit. Does anyone know what the application was for this speedmaster and what year they were used? This unit has a 21" driveshaft and is in need of a water pump cover.

[Raceman]

Welcome to Scream and Fly.

As far as a IV Speedmaster goes in outboard configuration it has an 8 bolt pattern that's not anywhere near fitting on your inline 6 mid section.......... not a single bolt will line up.

I'm unfamiliar with a 4 Speedmaster for the Mercruiser but I think a 4 for a Mercruiser is HUGE. Maybe if you post a picture we can help you identify it. If some of the bolt pattern lines up but NOT the front, it sounds like Mercruiser stuff to me. If Mercruiser it should have a fine spline on the driveshaft unlike the outboard stuff unless it's been modified and the driveshaft length is confusing also.

Incidentally, Merc didn't make 1500XS's in 1974. The only years of production were '76, '77, & '78. There WERE shortshaft 1500's available from 73 to 75 also, but they had some differences from the XS depending on year model.

You might find this thread informative:

http://forums.screamandfly.com/forums/showthread.php?t=25320&highlight=speedmaster

[crazy horse]

The old inline ssm's had two threaded hole in front of the waterpump housing. I'm not sure what you have but if it's got a 21 in. driveshaft, It ain't gonna fit a short inline center section. I've been messing with speedmasters on my inline off and on for about ten years and one of the hardest thing is find the right props. Like RM said a photo would help a whole bunch.;)

[ttorg]

Upon looking at the first picture in the 'Evolution of the Super Speedmaster', this is apparently what I have. It has the slanted exhaust outlet and the 1/2" thick back above the propshaft as well as the patent pending in the casting. It also has two pinions.
All but the front stud will line up with my lower units. I have two short shaft housings with the long shaft adapters. I have a new short driveshaft but don't think it will work in this lower unit.
I'd sure like to make this work but don't know how if it's designed for the Mercruisers.

[Mark75H]

What boat are you planning on putting this on? The usable options will be few and far between.

I think all the Mercruiser SSM's have the short stub driveshaft except for the MC-1's converted for use on Twisters; meaning if it has any significant driveshaft showing it is an outboard Speedmaster. If it is a left hand rotation unit, 135 hp will be more than it can handle for other than sprint use.


Water pump cover? Do you mean the water pump base that locates the 2 top driveshaft bearings? ... you won't believe the list price for that part.

[Raceman]

There are people around who can modify the driveshaft to any lenght/spline without disassemling the lower unit. A Speedmaster is something that you shouldn't tear into without experience and special tools. Unless the extra driveshaft is from a Speedmaster it won't interchange. The waterpump housing, both upper and lower are specific to the Speedmaster and nothing else fits it, BUT the impeller is the same as the std. gearcase.

Again, pictures would help get you better advice and pinpoint the part (s) you're missing.

As far as the prop hurdle that CrazyHorse mentioned, if that is an MC1 SSM it's either 14:15 or 1:1 gear ratio. There's very little difference between the two, but 1:1 is easier to put into perspective. If you put a 15 pitch propeller on a 1:1 it's roughly the same as running a 30 pitch on a 2:1. Props of lower than 15" pitch are virtually non existant for those gearcases.

[ttorg]

I have a 115 and 150 Merc, both short shaft but with adapters for long shaft that I plan to run on a 15' Hydrostream Viper. I'd like to run short shaft but could initially run long shaft if I can get it to work. It has 1:1 gearing. I'll try to take some pictures tomorrow. I have the water pump base that houses the gears and am in need of the pump cover.
Thanks for your continued responses.

[Mark75H]

I'd say its not worth the time to try either of those motors with the Speedmaster on the Viper. Not enough prop, too much boat.

[ttorg]

I finally got some pictures, but apparently the file size is too big to put on this site. I took them with the least resolution 640X480, but I don't know how to proceed from there.

[Raceman]

click on the tiny pictures link on the bottom of my post here and use that to hose 'em offsite.;)

[ttorg]

I've gone threw the Tinypic site and will try again to attach some photos. It still needs a water pump cover.

[Raceman]

Definately MC1. These were factory installed on Twister and Twister 1 in early '70's as far as their outboard application goes.

[Droll]

Definately MC1

Does this LU use the same water pump bottom part as the Super Speedmasters ?? , if so....the later SSM VI uses the same bottom part as the old SSM ( at least same part number ), the late VI uses a different top, but it might work ??

It's kind a pricey thou :eek:
Part #848505A1 , $646.18 WATER PUMP ASSY ....


Arne Kjetil

[crazy horse]

Man-O-Man ya gotta love Mercs price on that pump assy.:eek: Arne, The tops are the same on my MC-1 and one of my SSM's. I've never needed to find out if the bottoms are. But,I think bottoms are the same, I'm pretty sure they have the same Timkens in them and I robbed a base O-ring off a old junk ssm for my MC-1 a long time back.:D

[ttorg]

Do you have a part number for the water pump cover. If so, I could then try to find one.
Thanks for everyone's input on this. I'm still hoping to find a way to use this on my motors.