old mercury mods??

[Mark75H]

Jeff you are thinking of the T2x. The T2 used the regular twin rams like production motors.

[Raceman]

Jeff, this picture should show the two types of trim like Sam was talkin' about. I'll be glad to lend you one of the mounts for the cowl. Do you need the front and the rear?

[Raceman]

Good Lawd' that's a big image. If somebody that's computer smarter than me can shrink it and repost I'll deleat mine.

[sho305]

Ok, thinks I can get this there w/out smoking the modem....

[Chips overboard]

Hi guys , I know this is an old thread but I was wondering if anyone has ever changed the gear ratio on a 4 cyl 850 from 2.3 to 2.0 on a lite boat with a good hull, mite make a difference ? Like the merc V6 2.0 to 1.87 huge difference top end . I have recently done this to my 850 with reeds , 4 new 20 oversize high dome pistons ,cut the tuner 2 inches short and removed the can , also shortened to a 15 mid and added a 3 ram P/T system, aluminum lite weight flywheel and a Bobs low water pickup nose cone kit . but haven't tried it yet cause of the ice on the lakes . Any comments?Thanks in advance Chip

[Chips overboard]

P.S. This 850 is going on a 1968 300 lbs 14' V hull with factory pad GW invader, with a new hydraulic jack plate. Estimate on speed anyone????? This is the boat that broke the V bottom speed record in 1969 of 79 mph with a merc 1000 BP rigged by Mercury Racing Division at the time. Info gotten from Fiberglassic's under 14 ft GW invader Drag and Ski

[Mark75H]

It would have potential, but there is no guarantee - and because you would have to try so many different props to find the best speed, you would never know if the gear ratio change made the difference or just the prop that went the fastest


Long before I worked on the gear ratio (or nosecone) I would have squared the exhaust ports. There's a small but guaranteed power gain there, even though the work is monstrous

[Chips overboard]

Well, we will try many props if necessary .Cant stop now!!! lol

[Capt.Insane-o]

I'd love to see the 3 ram to 15 inch conversion. Neat project!

[Chips overboard]

I can tell you it wasn't a easy conversion . Had to move the tilt tube aft 2 inches and drill . Had to shorten saddle brkt and pivot pin, Then noticed that lower pilot wouldn't fit between the trim rams. Took a pilot off a old inline six and it made the swing between the rams. Only problem was when engine is a the lowest trim setting it only has 5 degrees of tuck cause the tilt ram is 1 inch too long so it bottoms out. I mite have to use reverse transom wedges from Bobs but will try it without them first.

[Capt.Insane-o]

Yeah..I messed around with it for my 1500 xs and gave up.

[Chips overboard]

It was a ton of welding and calculating but we think it will work fine . But that remains to be seen at this point. There were other modifications not mentioned that were painstaking as well like location of Trim ram landing pads and Bass pro Shops ram spacers and the degree angle positions. I would not do this again cause of the time at the welders and having to be there every step of the way to make sure all was straight with no binds

[Chips overboard]

Probably should have asked you while the powerhead was apart.

[Dave S]

There is a guy on here that just used a late 50HP 15 inch trim bracket.....1 ram...not so much work. Back in 1977 or so guy I built a 4 banger on 13 foot ally We used a SSM. No chine walk.....ran good but he missed having shift. On a small lite boat....OK.

[Chips overboard]

Funny you mentioned that ? I tried that and the Ram wasn't in the center , it was offset to the left looking from behind and couldn't adapt the exhaust housing to fit the 850 , Besides I was told that that system has some flaws . So I went with old reliable the 3 ram system. Plus the lower pilot would hit the single ram when fully retracted. Just so ya know I did think of doing that and had no luck with the 850 design. I did do it with a 70 3 cyl short and it worked out good