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1987 Mercruiser 5.7 I/O

bowtie

bowtie

Member
Experts, I am considering a Checkmate purchase that is powered by a 5.7 I/O Merc. The boat I am considering is (I guess from the 87 brochure)an Ambasadore and it is powered by a Merc I have never seen before. It is a 5.7 chevy fuel injected (from 1987) and it is not a throttle body type injection, but what appears to be a tuned port multi point fuel injection similar to what was used on the Vettes and Camaros of that era. According to the guy brokkering the boat Mercruiser only offered this engine for 2 years (1987 and 1988) before discontinuing it. Allegedly stock it was a 320 hp 5.7. Even to this day the highest output 5.7 Mercruiser is 300 hp, you have to go with the 6.2 (383) to get 320hp. Are any of you familiar with this power plant. Coincidentally this power plant is mated to a lower unit I am not familiar with (I admit to being relatively new to I/O power plants). It is allegedly mated to a Alpha One SS. The broker also claims these are no longer available, but they were the best Alpha ever made. This one does have a much sleeker profile (almost like a #6 race drive), and is allegedly equipped with a 1.36 drive ratio gear set. The motor in this boat was rebuilt in 1995 and it comes with the alleged build sheet and accompanying dyno sheets. The dyno sheets show 425 hp and 445 tq (corrected) and the broer claims the boat has a top speed of 80 (yet the speedo does not work). Anyway, any feedback I can get on this combo would be much appreciated.
 
Experts, I am considering a Checkmate purchase that is powered by a 5.7 I/O Merc. The boat I am considering is (I guess from the 87 brochure)an Ambasadore and it is powered by a Merc I have never seen before. It is a 5.7 chevy fuel injected (from 1987) and it is not a throttle body type injection, but what appears to be a tuned port multi point fuel injection similar to what was used on the Vettes and Camaros of that era. According to the guy brokkering the boat Mercruiser only offered this engine for 2 years (1987 and 1988) before discontinuing it. Allegedly stock it was a 320 hp 5.7. Even to this day the highest output 5.7 Mercruiser is 300 hp, you have to go with the 6.2 (383) to get 320hp. Are any of you familiar with this power plant. Coincidentally this power plant is mated to a lower unit I am not familiar with (I admit to being relatively new to I/O power plants). It is allegedly mated to a Alpha One SS. The broker also claims these are no longer available, but they were the best Alpha ever made. This one does have a much sleeker profile (almost like a #6 race drive), and is allegedly equipped with a 1.36 drive ratio gear set. The motor in this boat was rebuilt in 1995 and it comes with the alleged build sheet and accompanying dyno sheets. The dyno sheets show 425 hp and 445 tq (corrected) and the broer claims the boat has a top speed of 80 (yet the speedo does not work). Anyway, any feedback I can get on this combo would be much appreciated.
 
maybe try calling the factory- or merc?? as far as the 425 hp anything is possible- but thats a pretty hi powered small block- personally I would worry about the reliability of an engine that tweaked!! A car can easily be towed a boat may be another story!! let us know what you find out!!
 
Well, I took the boat for a demo last week and was fairly impressed. It was a little sluggish getting up on plane, but ran extremely well after that. We cam across a 25 ft Howard and decided to try our luck running against him. He crept away from us a little, but for the most part we were side by side. After we both shut down we pulled over and were talking to the guy (he was extremely friendly and claimed he had a similar boat years before). Anyway he said his Howard had a Teague 509 with a Bravo XR drive, stainless headers, etc. He said he was just out testing a new prop which he did not like very much, said he turned his motor about 6,000 while running us (we turned about 5600-5800). We asked him how fast he was going and he said he was running about 86mph (said he could run 90 with his old prop at 5800 rpm's). He had a hard time believing the Checkmate had a small block and was for the most part keeping up with him. It pretty much sealed the deal for me, now I just have to make the offer to the broker. I just wish someone some where had some knowledge or experience with this combination.
 
I have seen that motor and drive combo at a NYC Boat show several years ago. I dont know why Merc discontinued them, but I would be leary about getting involved with it soley from the stand point of parts availability. I seriously doubt you were running 86 mph. What prop, gear ratio and rpm were you at?
 
straight up - efi parts are nla - we have one here that is getting a carb coversion. kind of a goofy set up - the ecm is actually an outboard ecm. the engine was a 320hp. Alpha ss drives were an inch or so shorter than the standard drive - alot of the parts are standard old alpha stuff, except for the driveshaft which is nla i believe. Just keep in mind, with parts getting scarce, reliabilty should be a great concern.
 
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by vinny p.:
I have seen that motor and drive combo at a NYC Boat show several years ago. I dont know why Merc discontinued them, but I would be leary about getting involved with it soley from the stand point of parts availability. I seriously doubt you were running 86 mph. What prop, gear ratio and rpm were you at? </div></BLOCKQUOTE>
I agree that we were not going 86, that is what the guy in the Howard claimed he was running, but he was just barely walking away from us. They claim the boat will run 80 and from that one experience it seems pretty close. I have no idea what pitch the prop is being as I have not even taken possesion of the boat yet, all I do know is that it is a 3 blade stainless and appears to be lab finished. I do know it has the Alpha SS drive with a 1.32 ratio and the guy driving it at the time claimed he turned it about 5800 rpms (the motor supposedly dyno'd 424 HP and 445 TQ). Later when I drove it and opened it up I turned it about 5500-5600, but most likely did not have it trimmed up as much as he did.
 
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Chris E:
straight up - efi parts are nla - we have one here that is getting a carb coversion. kind of a goofy set up - the ecm is actually an outboard ecm. the engine was a 320hp. Alpha ss drives were an inch or so shorter than the standard drive - alot of the parts are standard old alpha stuff, except for the driveshaft which is nla i believe. Just keep in mind, with parts getting scarce, reliabilty should be a great concern. </div></BLOCKQUOTE>
Greattt... I sort of wish I had heard this sooner. I just sealed the deal this morning on buying the boat. I had already decided the drive was the weak link in this boat so I will try to take it easy with it. I will need to find out more about this EFI setup. Allegedly when the motor was refreshed and hopped up (forged pistons, Dart heads, Crane cam, roller rockers, etc.) back in 1995 they dyno'd it once with the stock ECM, then replaced the ECM and it picked up about 10 hp and 10 ft/lbs. I am not sure if they just replaced it with another stock ECM, or an aftermarket replacement. I quess I will have to find out.
 
That would be a good boat for a 496 H O and a bravo xr
Then you could sell me the combo in the boat for a couple of hundred since it is out of production and all!!!!
 
wow an Ambassador going 80+ Where is that 2nd mortgage paperwork I had filled out? like i get to run it flat out now....yeah right wife and kids say they are scared!
 
Im looking for one of these KOOL (odd) 1987 320 HP 350 MPI Mercruiser, injection set ups for a Hot Rod, I drive when I can get to my boat. Just the Injection, NOT FOR MY BOAT
Thanks TUSHMAN
"NO FEAR" Is a LACK of HP
 
straight up - efi parts are nla - we have one here that is getting a carb coversion. kind of a goofy set up - the ecm is actually an outboard ecm. the engine was a 320hp. Alpha ss drives were an inch or so shorter than the standard drive - alot of the parts are the mind, with parts getting scarce, reliabilty should be a great concern.

Do you still have the injection you replaced with a carb??? TUSHMAN
 
MPI

Chris E said:
straight up - efi parts are nla - we have one here that is getting a carb coversion. kind of a goofy set up - the ecm is actually an outboard ecm. the engine was a 320hp. Alpha ss drives were an inch or so shorter than the standard drive - alot of the parts are standard old alpha stuff, except for the driveshaft which is nla i believe. Just keep in mind, with parts getting scarce, reliabilty should be a great concern.
Click to expand...

Do you still have that MPI set up ?
Thanks Tushman
 
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