Mercruiser 3.7 to 5.7 swap

[Geojojo]

i bought my 19 foot 1986 Chaparrel 187 for $1200 in 2012, had a great summer on it, but started having many issues with it, mainly it developed a rod knock, and secondly, i felt like it was an underpowered engine for the boat, so starting January 2015, i began work
i started by pulling everything out of the back of the boat
the boat had no power steering, and an alpha one first generation setup
using craigslist, i slowly found everything i needed to change it all to a second generation setup
as well as a 5.7 liter/350 v8 mercruiser engine
i am currently done assembling the boat and all i need is a trailer, ive located one and im going to buy it on sunday
then hopefully take my finished project boat out for the first time with the new assembly

the boat before the project began

the 3.7 liter in the boat

pulled it out using the electric winch from the trailer

 

[thumpar]

Did you change the drive ratio or put a different drive on it?

 

[achris]

I'll move this to resto forum...

 

[Geojojo]

yes, i changed from a 1.87 to 1 ratio alpha one first gen, to a 1.47 to 1 ratio alpha one gen 2, new gimbal, transom plate and all

 

[Geojojo]

i put the boat in sunday, ran great all the way out, i changed the fuel filters once i came back to the dock after about 30 minutes of runtime on sunday, but it has a stalling issue, it will reach between 2500-3500 rpms and then just die like the key was turned off, i checked the fuel filter again after running it again tuesday and its nowhere near as dirty as it was and had maybe a drop of water in it, but the stalling issue remains
any suggestions?

 

[Geojojo]

http://i.imgur.com/q8FywsX.jpg

 

[achris]

Post this up in the Mercruiser forum as a new question. You should get lots of help...

 

[Watermann]

She's a looker for the age. Nice upgrade! Post a pic of the new power install

 

[Geojojo]

im having problems uploading pictures, any tips? im trying to upload from an iphone 4s

 

[achris]

Load to a photo hosting site, and post the link here.

 

[Geojojo]

http://i.imgur.com/8plPfHo.jpg
http://i.imgur.com/jct6Yzi.jpg
http://i.imgur.com/mWM8RT5.jpg
http://i.imgur.com/sCj9XRz.jpg
http://i.imgur.com/AAZaluu.jpg
http://i.imgur.com/iT25XNd.jpg
http://i.imgur.com/pDHw94o.jpg
http://i.imgur.com/Ke5At0T.jpg

 

[JaCrispy]

Cool swap.

I have a 22'er with a 5.7 Alpha One. I bought it last year and had a HELUVA time chasing down a fuel issue. The boat would run fine up to ~3000 rpm then stall out. I did everything from drain the fuel tank, replaced the fuel check valve, fuel line, fuel pump, filter (3-4 times), rebuilt the carb and blew out the steel lines, replaced and rerouted the vent. Basically, replaced/inspected the whole system.

Finally figured out the problem. One time it stalled out, I went to remove the filter and heard a "hiss". Ever since I got the boat I just used Napa filters since I have a business account there. For some reason the Napa was creating a vacuum. I replaced the Napa with a Sierra which finally fixed it. I have no idea why the Napa filter doesn't work, but it doesn't. Never had a problem since.

 

[Geojojo]

Turned out It had a load of trash crammed in the pickup tube, cleared that out and she runs great!!! After trimming it out on some flat calm water I got 47 mph out of it with a 23 pitch prop which is way too much for it because it only puts out 4000 rpms, then I tried a 4 bladed 21 pitch stainless steel prop which put me at 41 mph at 4400 rpms, but it sounds like it's under a lot of load at that speed with the 4 blade so next I'll try a 3 blade 21 pitch stainless steel and let you guys know how it goes

 

[redlinj]

I'm in the middle of the same engine swap and am about to start the new engine mount fabrication. Your angle brackets appear to be thru bolted to the original stringers. Seems like a relatively simple setup! How are they holding up?

 

[Geojojo]

No Title

 

[Geojojo]

The best speed I managed was 47 mph, and even with a v8 I still get over 3 miles to the gallon when I throttle back and cruise, I'm very happy with this swap and recommend this to others, feel free to ask any questions if you're curious