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Clams Canino
07-02-2002, 09:43 AM
I've been too busy with silly stuff - like working on outboards and BOATING <grin> to do too much more for a bit.

Would this be a true statement:

The 1500 got the lower dome pistons (in 19XX?) and became the 1400. Then when the HP ratings changed the 1400 became the 1150 and the 1150 became the 900.

?

-W

Mark75H
07-02-2002, 04:24 PM
I don't know if the low dome piston change occured at that time. What did occur: introduction of the 150hp V-6. You can't sell a 150 V-6 and inline at the same time, so the standard 150 inline became 140 in 1978, but the 150xs stayed on at 155hp. In 78 you could get a 90 hp inline, a 115hp inline, a 140hp inline, a 155hp inline or 150, 175 or 200hp V-6.

1978 shows as the last year of the xs in my literature.

The change to propshaft rating came in 1984. 84 and later only 90 and 115 inline 6's show up.


I have to go back to race prep. Denton, MD July 13 & 14

jnewtonsem
07-02-2002, 05:39 PM
Officially Merc changed to Prop rating in 84. However, I'd heard the actually started before then. I've got Merc service book that lists the change of the 90-200 hp's by s/n. About 80 or 81 models.

Mark75H
07-02-2002, 06:52 PM
I think you are correct, but that it only applies to a few of the smaller models, not the high horsepower 3's, 4's and 6's.


Example: the 44ci 50hp 4 stays rated at 50hp until it drops back to 45hp in 1986.

All we are concerned about in this thread is the inline 6's.

Lets see if our serial number data agrees: my book shows the propshaft hp 115's starting with 644183. If the Merc list shows them starting with a 56xxxx (or so) number then we are in need of that list to keep things straight.

Clams Canino
07-02-2002, 07:03 PM
What's the deal with 1983? I see a 115 listed (I assume it's the PH rated one) but where's the 140?

The serial number Sam quotes is 1984 - 83 has a hole.

-W

Raceman
07-02-2002, 07:51 PM
I'm not sure exactly when the low domes occured either, but the lowering from 150 to 140 was just as Sam said, marketing rather than engineering.

The 140 never became the 115. The 115 always had different port timing although it did get the power ported piston as the 150 and 140 (late style had). By late style, I mean the 78 and newer as opposed to the 72 model 1400 which was identical to the 73 and newer 1500 EXCEPT for the power ported pistons.

jnewtonsem
07-02-2002, 08:08 PM
The book indicates ratings start earlier than that: 90"s S/N 5721325 and up, 115s S/N 5861527 and up, 150 (v-6) 6038681 and up, and 200 S/N 6055033 and up. These numbers indicate 80 or 81 for the 90 and 115s and 82 for the 150 and 200s.
The book is a service training notebook published by Mercury in 1990. Section deals with dual outboard installations and warns that mixing a higher and lower SN on the same boat will cause problems because of the different HP ratings. "Bass and Walleye Boats" did an on Outboard power recently and stated that 84 was the official changeover, but Merc stared several the process several years earlier.