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New to me BIII

o2batsea

o2batsea

Outstanding Contributor
OK you all will probably hate me but I just picked up a complete 7.4 MPI Bravo III for cheap that I'm going to install in my Allmand. 215 hours on it.
Looks like it will def need anodes. Along with belts, hoses,plugs, wires cap rotor, fluids and filters, what else should I be doing to tune this up before installation?
 
Elbow grease,rags, patience,and bandaids, o2batsea you seem to be one of the seasoned veterans here on this site, I think you have it covered, Maybe check basic timing and valve lash? Is it injected or does it have a carburetor ?
 
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What's the X dimension? If it means ripping out the old motor mount pads and epoxying in new ones, well, that's not a ting really. It will add about 200 lbs to the stern, so it might be a little bit lower in the water at rest. Yes it is fuel injected.
Current drive is an OMC Cobra with a Ford 302 V8
 
The "X" dimension is the height of the transom assembly/Crankshaft line when it is installed in the hull.

Easiest way to check is to measure the omc drive and compare it to the Bravo 3. Measure the distance from the center of the input shaft to the center of the output.

I am going to say that your OMC drive X dimension is going to be different from the Bravo3. A Bravo one or two will work better.

Here is a link....This will tell you everything you need to know.

http://www.boatfix.com/merc/install/gas/86017211.pdf
 
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Oh that, well as you know all OMC, volvo and mercruiser use the same hole and bolt pattern as well as input shaft splines ( one could, in thoery, mount a mercruiser outdrive to an OMC or Volvo inner transom). The height of the hole up down the transom depends on a variety of factors, and is more art than science. I think I'm good.
Also that guide is for the small block 4.3-5.7. Mine's a big block. That shouldn't really matter tho except for the added heft
Worst case is that I have to redo the transom cutout.
 
The Bravo hole is slightly different i believe than the Alpha. Some slight modification is needed so to be sure make sure you test fit the transom assembly first.

Therefore it would most definitely be different than OMC
Just test first.

If the whole needs any modifications I would go upward.......................more top speed!!! 1/4 inch will make a lot of difference from What I have been told.
 
OK I went yesterday and helped cut this monster out of the (POS) Chapparal hull that it was living in. Oh gawd, the engine was held in place with 4 3 1/2 inch lags into a thin skin of glass over wood. Good thing this was a trailer queen else the engine probably would have come loose from its moorings at the first big wave...anyway it's out and at my barn.
Problem #1. The exhaust manifolds are so rotten there are no discernable bolt heads showing. One side is holed thru from rust. Other than this, there doesn't appear to be any other real problems, at least externally. If anyone has any brilliant ideas about getting the old manifolds out, I'm open to suggestions. Not relishing drilling 16 bolts out.
That may be what killed this boat. The hole in the mani surely deadlined the boat and if a mechanic took a look in there, they'd be quoting huge money to replace them in place. There's no way the engine could easily be removed for such a job. Clearly the deck was bolted on after the engine was put in.
OK any way, moving on...
Will do the usual...cap wires plugs filters belts hoses. Have to get a manual.
Also the engine mounts are quite toasty...need new.
I think I will take the drive to a place near me and have them go thru it. It will def need new anodes, and the one on the bearing carrier is beyond what I feel like fooling with.
One other thing I will be converting to hydraulic steering so I assume I don't need the power steering pump and the associated plumbing, right?
 
Get a die grinder and take what is left of the bolt heads off. Then slide the manifold off. Check the cylinder head bolts after you get the manifold off.

Post the serial number. I may have some stuff for that engine if needed.
 
x 2 for grinding bolt heads off, use heat, penetrating oil, and a pipe wrench on what's left of the bolt. That's worked well on old car exhaust for me in the past. Left hand drill bit if the bolt snaps at the head.
 
Dieter said:
x 2 for grinding bolt heads off, use heat, penetrating oil, and a pipe wrench on what's left of the bolt. That's worked well on old car exhaust for me in the past. Left hand drill bit if the bolt snaps at the head.
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Ditto.... Left hand drill a.k.a. broken bolt extractor Sears has? (had) a reasonably priced kit @ one time. If that fails.. I had a bolt break in an aluminum block (O/B) once (corrosion on the bolt @ first thread on bolt in the block). Did not want to use an extractor for fear of it walking and ruining block. Spent HOURS with a Dremel and a magnifying head mounted lens ( and a high intensity work light) and a small conical stone grinding enough of bolt out so I could peel the remaining bolt out of the thread roots in the block. This resulted in some damage to the threads, so I installed a helicoil insert as added security.
 
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o2batsea said:
vst on top yes
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ok now for the not so good news. This fuel injection setup is subject to boiling the fuel inside the vst, hence the giant fuel cooler. If you engine room is restricted in size this may be a problem.

I am in the middle of rebuilding(will be done today) the same engine and did away with the VST, the cooler and the fuel pump driver/water pump.
 
Well, first things first Chris. I'm going to get it installed and running, After that I may take you up on your VST fix if it proves troublesome.
Engine room is not a room really. More like wide open to the world at the moment. I have a cover but not sure if it will fit the bigger engine. I'm guessing that a hot engine room will not be a friendly place, but in my case it will get plenty of fresh air.
If you want to get rid of those take off parts, let me know I'll pay shipping!
 
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Well at a minimum pull the VST and service it. The filter inside will need to be cleaned. Also, don't wig out over the price of the filter from Mercruiser. PN 808504 1

The Yamaha filter will replace it for less than $40.00

I would try and find the Mercruiser Gen 2 fuel cooler and install it before you drop that engine in because There is a good chance that your fuel pump driver has never been serviced and is wrecked internally.
 
Yeh we will see. The engine was really just a gimme as I was really only paying for the drive. If it runs, great. If it needs to come apart, well, it's worth doing since it was basically zero money. Hour meter shows 221.
 
Yup it's froze. Will do the unstuck thing over the next few weeks and see what we have once I get it loose. Prolly one or more cylinders bad.
 
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