Re-Building a 3.0 140 hp

[johcar2]

I know there is nothing major wrong with this engine as it does run, but only on three cylinders. So I'm assuming I'll be pulling the head and going from there.

So, for those who have re-built the 3.0, is there anything you would have done different; mill the head, port and polish the head, change the cam grind, change the carb, etc. Installing larger valves is out of the question, too costly, as I plan to use most, if not all, of the existing valves.

I know a couple of mechanics (you know, the ones who cannot leave anything stock) and also a machine shop that can do just about anything I need.

tia
John

 

[third times the charm]

Re: Re-Building a 3.0 140 hp

I know this is a dumb question, but did you check the basic stuff, plugs, wires, coil , etc, etc. it could be something simple as a bad plug or wire.
but if you have the same luck as most guys on here then well........ lol

 

[alilley]

Re: Re-Building a 3.0 140 hp

yes i have rebuilt one. Would i worrie about going through it and trying to make a hot rod out of it????? NO. this is a 4 cyl we are talking about here. Yes there are some extreamly hot rodded 4cyl out here (some guy in kansas city area is getting over 500 hp out of the iron dukes) but the cost to do it really is not worth the return. As i was advised to do wehn i was thinking the same thing........if you a hot rod boat then get a v8........one thing to always remember (this is something a couple old hot rodders told me) "IT TAKES FUEL TO MAKE HORSE POWER" so if you want to spend the money on souping up a 4 banger then go for it but even after you wallet cools off from that then you will still be paying for it at the pump

 

[johcar2]

Re: Re-Building a 3.0 140 hp

I know this is a dumb question, but did you check the basic stuff, plugs, wires, coil , etc, etc. it could be something simple as a bad plug or wire.
but if you have the same luck as most guys on here then well........ lol

Yes, I've been through the easy items. Got new plugs, wires, points, etc. and even did a compression check. #3 is at best 45 lbs, rest are around 130. Also know there is water coming out from under the manifold. So the top of the engine has to come apart to find our more.

 

[kd7isf]

Re: Re-Building a 3.0 140 hp

So,

you are probably missing a drain plug in your manifold (thus the water coming out from underside of your mainfold).

Running on 3 cylinders IS a major problem. How does your oil look?

Need to figure out where the compression in the bad cylinder is going.
Bad / burnt / warped / pitted / bent valve, worn rings, crack in cylinder face, cracked or burnt piston, etc........

Hopefully your oil looks like oil and not a milkshake. If it looks like a milkshake, you have water getting into your oil somehow....

Remember the old saying, marine engines do not wear out -- they rot out

I would remove the manifold, then pressurize the bad cylinder with compressed air and see where the air leaks out. Intake port = bad intake valve, exhaust port = bad exhaust valve, vent on valve cover = leaking or bad piston rings.....

Then pull the head and have a look. Could be as simple as a blown head gasket.....

Adding performance mods to the 3.0 to gain excessive hp is not a good idea.
Remember that most of these gains are PEAK gains -- yes, you can mod a 3.0 to give you 500hp -- but it will only last for about 5 min in a boat....
An engine in a boat is ALWAYS doing the equivilant of driving up a steep hill with your foot on the floor -- much different than an engine in a car that only gives peak horse power on hard accellaration and spends most of its time cruising at 1/8 - 1/4 power...

 

[johcar2]

Re: Re-Building a 3.0 140 hp

The oil is oil, no water in it, so it is somewhere in that top end. Will start the tear down process soon. I'll let you know what I find. Thanks