Origin of OMC Triumph 55

[FUJIMO]

[dale robertson]

The dog nuts are missing.

[powerabout]

true

[ChrisCarsonMarine]

Proper term is "monkey balls"

[dale robertson]

Proper term is "monkey balls"

Looks like I was wrong on both accounts. The Monkey Balls (dog nuts) don't show up in the parts book till the 1970 60h.p.

[powerabout]

so in 68 you rev it up and turn the key off and get a bit of a shock?

[dale robertson]

so in 68 you rev it up and turn the key off and get a bit of a shock?

I thought they all had the shift diodes (dog nuts) so they wouldn't shift into forward as the motor spooled down. I was surprised I couldn't find them in the parts look up for the 55 h.p. . I don't remember trying to rev one up and then turning the key off , but I do remember them going into forward at idle when the shift diodes (dog nuts) were bad and you turned the ignition off. Maybe that was normal with the 55 h.p. The shift pin was spring loaded to push the clutch dog into the forward gear as a fail safe , so you needed oil pressure for neutral and reverse. When the oil pressure got lower than the spring pressure you end up in forward gear.

[2us70]

How long did OMC use the electric shift lower units? I was wondering if they were still in use in 1973?

[dale robertson]

How long did OMC use the electric shift lower units? I was wondering if they were still in use in 1973?

1972 was the last year. They kept the oil pump but used a shift rod to control it.

[2us70]

At some point they went to a lower unit that looked to be about the size of the Mercury 650 and 500 units. Do you know when that was?

[Mark75H]

At some point they went to a lower unit that looked to be about the size of the Mercury 650 and 500 units. Do you know when that was?

'73 and '74 I think. That's when my book lists the Johnson Stinger II triple. Wasn't the Evinrude case called the Nitro?

[powerabout]

'73 and '74 I think. That's when my book lists the Johnson Stinger II triple. Wasn't the Evinrude case called the Nitro?

yes was on all the 15" 70hp engines.
Same guts with new case is the sst60 lower

[lars strom]

The smaller (later called Nitro) gear case came out 1974 in a limited production 70 HP 15 inch race model.
The standard 70 HP 15 inch 1974 model still used the larger gear case.
1975 was really the first year for the smaller gear case on the 15 inch 75HP.

[2us70]

I remember that the larger unit was working pretty well on the E Production boats. I was running a 650 against them and having trouble keeping up in 72 and 73. I ran the same motor on a SE boat several times in 73 and did quite well against them. 74 went back to a 500 in SD. Same props old SE boat.

[FUJIMO]