Super Speedmaster Question?

[Mark75H]

I just noticed some SSM's have a cavitation plate that is "squared off" at the back and some are more round at the back. Does this coincide with the case change omitting the little inspection plate cover?

Looks like the SSM-III might be the square tailed guy and the earlier SSM's still more round like a single pinion Speedmaster.

[Jeff Ettinger]

Mark75H

Not sure that it is related to the cover disappearing. Seems that there were some rounded ones with no cover. I'll have to go look, but I believe that the square back appeared around '73, maybe?
Jeff

[Raceman]

Sam, I'm not familiar with the Speedmaster III designation. As I've told you before, I've got 11 SSM's in several different configurations and I've never had a square backed one that had the cover. One thing that I've noticed that isn't consistent with the catalogue pictures through the period is that there seems to be some difference in the exhaust snouts among the square backed ones. All the square ones that I have are the two level snout type, with the rear of the lower level closed, with the rear angled up at about 45* to the upper level. Most of the ones shown in the cataloques through the 70's seem to have both the upper and lower level open on the back, although the lower is of course shorter, front to rear, for prop clearance. I've always thought the one with the lower level closed was the latest design, and the only one with the square rear, but can't find it anywhere in a high perf catalogue except on the 3 cyl's from the 80 catalogue. I don't believe they ever used a square back on a T2, at least none I've ever seen. I don't think they did on the T2X either, but mine aren't original enough, nor do I know enough about the history of these two, to be very confident in them for historical referrence.

Of the 6 units I have at home, only 2 are square back and they both have the 45* exhaust and no shim cover. One of them is in the picture attached here.

Regardless of the timeline, I believe the unit pictured here is the newest design.

[Raceman]

The exhaust shown here is the type shown in all the Merc catalogues through the 70's on all engines. Even the 2 liter champ motor in the 80 catalogue AFTER the 2.4 liter OZ motor got the #6, still showed this style exhaust, open on both levels with the lower one longer than the 45* style. It's hard to tell in the catalogues which style the the cavitation plate is at the rear, or if they had the small shim cover. The unit pictured here is round and does have the cover.

[Mark75H]

Thanks, Raceman. I just made up the III designation because 3 usually comes before 4 and I think we are looking at the last incarnation before the newer bigger Super Speedmasters.

I'm wondering if the square tail represents a new die in use because the old one finally wore out. If no one was using the shim access cover, leaving it off a new die would reduce the labor costs of finishing out castings made with it, but I can't see making a new die just to eliminate that amount of work.


hold down the "Alt" key and press 80807 while holding to get º

there is a shorter code for it, but 80807 is easier for my often confused brain to remember. 80806 is ª and 80808 is ¿


I've been puzzling over why the original Speedmaster finally came out in 1961 after being promised by Strang since 1956. The 1960-64 time period was a pretty weak one for non-essential purchases. Weak enough that the Merc 1.5:1 Sportmaster was a flop. But I think I found the reason the Speedmaster was released then regardless: in 1961 McCulloch released their "Sportsman" 1.1:1 gearshift unit and close on its heals in 62 released their full race unit on their racer. If Merc hadn't released the Speedmaster, McCulloch might have had a clean sweep of all the big races and became the preferred motor for racing. Kiekhaefer probably had enough spies in the Minneapolis plant to know they were setting up the tooling and rushed the Speedmaster to market. It shouldn't have been a difficult job.......the internals are heavily based on the 1957/58/59 Mark75H lower unit and the whole project had been at least partially underway since 56.

I bet "Alex" [Charlie Alexander] would know, maybe Herr Rose as well.

[crazy horse]

Did they square off the speedmasters when they squared off the standard gercases :confused:

[JAFFA]

Just thought that Ive seen those style of boxs on the 700xs wondered if you this was a continuation from the T2x T3? as 700xs was later wasnt it?

Twistin

[Mark75H]

JAFFA, the 700x came out about the same time the T2X did, certainly before the T3, and you are correct about the time frame. The question is whether the square tail cavitation plate and inspection port were changed at the same time.