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- Drives and Lower Units (https://www.offshoreonly.com/forums/drives-lower-units-217/)

- - #7 info (https://www.offshoreonly.com/forums/drives-lower-units/370747-7-info.html)

Quote:

Originally Posted by JaayTeee (Post 4781189)

https://www.mercruiserparts.com/bam/.../31026/2322/60

here’s a breakdown of the lower for a 7

they were marketed more for an express cruiser type of boat

Yes these are not SSM, more of a cruiser drive like a Bravo 2 or TR or the original #3 (not the speedmaster we all know & love) but with more capacity.

Basically a 6 upper with a large diameter single pinion lower. Not exactly popular I am not sure how many actually wound up on boats.

I think they had the same spline as a 6. I bet Mel Riggs could tell you for sure.

Quote:

Originally Posted by 999JAY (Post 4781275)

From what I remember Nick there a wet-sump version of the #6 with less reduction and bigger gears and I am sure a lot of the internals are obsolete now, I would baby them with the low input speeds you have and large pitch props.
J

that's my plan. its supposed to have 17 3/4 x 28pitch 4 blades with 600hp. swapping in 820hp engines. wondering if I should stick with 4 blades or go to 5 blades and run up to say a 35 pitch....

Quote:

Originally Posted by Mbam (Post 4781387)

ok, thanks for the info. yea, not many made at all. supposedley only 3 of my boats were made so finding info on the setup is hard to non existent.

I have one of these #7 drives, new in box.
It will bolt to a #6 gimbal.
Uses #6 props
1:1 ratio.

My plan is to put it on my single engine 30' Cobra cat. Will use a Ford 6.0L diesel engine. 26-28" prop and run/cruise at 80mph at 4000 or lower. And get over 3mpg.