3.7 (170) Blew a hole in the side of the motor! (3.7 vs 3.0 advice)

[bill2014]

So the 3.7 in my 1986 stingray bowrider decided it had enough on the 4th, the knock that I was suspicious of came to an end. Rod number 4 decided to knock a hole in the side of the block. Now that I know this engine is beyond repair I need help on deciding what todo next. I have done a lot to this motor and drive and know them both very well. I have found a used merc 3.7 for sale in my area for $1200, and it would drop right in, but they certainly do have their issues. I have also found a 3.0 with drive for $1500. I am considering putting the 3.0 in as it is a more reliable engine. I have also heard that because the 3.7 was rated at the crank and the 3.0 at the prop the power difference is not as extreme as one might think. I am just wondering what everyone's opinions are and if the 3.0 would use the same alpha one gen one transom mount?

Thanks!

 

[stonyloam]

Ouch, that’s ugly! Admittedly I am a 470 fan, and have driven boats with both engines, and I think you would be disappointed with the 3.0, besides the outdrive gear ratio of your current setup is wrong for a 3.0. As far as reliability goes, a 470 is every bit as reliable as a 3.0 if you maintain them properly. Plus you have lots of parts. Go 470 IMHO.

 

[nola mike]

Idk, I think there's a big difference between the 2. My next move is going to replace the 3.7 with a 4.3. Why would you want to put all that time and money into a slower boat? Those prices are also pretty high. where are you located?

 

[Rick Stephens]

I have had 4.3 now replacing a 3.0L. Would not go back. Find a junker boat and the motor is a dream to work on, parts, blocks and used stuff galore with a 4.3. 3.0L parts are more expensive.

 

[stonyloam]

Idk, I think there's a big difference between the 2. My next move is going to replace the 3.7 with a 4.3. Why would you want to put all that time and money into a slower boat? Those prices are also pretty high. where are you located?

say it ain’t so Mike! Yeah, if you go with something other than the 470 the 4.3 is the way to go. But if you get that 470 it is a plug and play. Also you will need more than 3 minutes to winterize.

 

[Scott Danforth]

So the 3.7 in my 1986 stingray bowrider decided it had enough on the 4th, the knock that I was suspicious of came to an end. Rod number 4 decided to knock a hole in the side of the block. Now that I know this engine is beyond repair I need help on deciding what todo next. I have done a lot to this motor and drive and know them both very well. I have found a used merc 3.7 for sale in my area for $1200, and it would drop right in, but they certainly do have their issues. I have also found a 3.0 with drive for $1500. I am considering putting the 3.0 in as it is a more reliable engine. I have also heard that because the 3.7 was rated at the crank and the 3.0 at the prop the power difference is not as extreme as one might think. I am just wondering what everyone's opinions are and if the 3.0 would use the same alpha one gen one transom mount?

Thanks!

there was a 3.7 block on ebay for only a few hundred. couple that with an edelbrock aluminum head for the ford 460 with new oversized ford 460 rods and pistons, then you only need to have your crank ground and the block honed. you can do all that and have a better motor for about $1000

say it ain’t so Mike! Yeah, if you go with something other than the 470 the 4.3 is the way to go. But if you get that 470 it is a plug and play. Also you will need more than 3 minutes to winterize.

so put a heat exchanger on the 4.3. the only saving grace of that platypus is the heat exchanger and that is only after it was upgraded to the 4"

 

[nola mike]

say it ain’t so Mike! Yeah, if you go with something other than the 470 the 4.3 is the way to go. But if you get that 470 it is a plug and play. Also you will need more than 3 minutes to winterize.

Ha ha, well, I've been talking about it for a few years. Still no actual action. Yeah, I like my 470, it's been pretty good. Got a compression reading of 131 in #1 though, so the end may be getting near.

 

[bruceb58]

Unless you absolutely love this boat and it's in incredible shape, sell the boat as is and buy a boat with a better motor.