Merc 3.7 165hp Head tuning,cam,valves,carb.?

[flinty]

Hi, I just sold my last boat(mercury 135 v6 outboard) and just bought a mercruiser 165hp 3.7l inboard on a 18ft fletcher, Problem is, its a little slower than the outboard, infact quite slower, question is , Can the head be stage 2 tuned they call it in england, open ports larger valves, and a race cam, i work on car engines and know this can be done to great effect, and what about alarger carb , its TINY ! on it now, surely i can make this motor sing. Are these parts available? are the big ends strong enough on these engines?<br /><br />Ambitious maybe . regards, Wayne

 

[flinty]

Re: Merc 3.7 165hp Head tuning,cam,valves,carb.?

Sorry for got to say its a 1990 outfit.

 

[Bondo]

Re: Merc 3.7 165hp Head tuning,cam,valves,carb.?

I'm not real knowledgable about the 470s...<br />But, I know Merc. built a few with 4bbl. carbs... 190hp I think.... The Hot Cam will be real hard to find.... Only Merc. has ever built, or used this motor.... It's a Mongrel Merc./Ford endeaver...

 

[MrBill]

Re: Merc 3.7 165hp Head tuning,cam,valves,carb.?

The 3.7L inline 4 was produced 1987-1989 and put in some 1990 craft. As you amy have read on this forum, there are some "quirks" with this power plant, but you will find that over-all, owners tend to feel very confident the engines' reliability. All versions of the 3.7 had closed cooling systems and require attention to the lower unit impeller for proper cooling. Let's not go into too much detail...do a search for more info. The easiest way to increase HP is with carburation, 4bbl will bring it to 190HP. Check WOT at about 4600 RPM and prop accordingly. Cam will be expensive due to position and drive of water pump, and head work may be prohibitably expensive for a 13 year old boat and motor. Thnik about enjoying as is...or trade up.

 

[flinty]

Re: Merc 3.7 165hp Head tuning,cam,valves,carb.?

Thanks for replies, Think about enjoying as is...... or trade up. These are wise words i will take heed and enjoy what i have for now, and trade it in peak season.<br /><br />thanks guys.

 

[Brzwrking]

Re: Merc 3.7 165hp Head tuning,cam,valves,carb.?

I have several 4bbl intakes and carbs available for this motor. Incorporates an oil cooler in manifold. Runs the same cam.<br />Kevin<br />727-539-8463<br />www.breezeworks.net

 

[Salty Dog]

Re: Merc 3.7 165hp Head tuning,cam,valves,carb.?

Brzwrking, are you familiar with these motors? I have a Sea Ray in SW Florida that has 2 of the high hp 4 barrel versions in it. I go up to Largo alot and I have a couple of questions for you and might sell it also.