4.3 L automotive engine

[AlfaRs]

My 91' bayliner has an engine with a cracked block (bought it that way). I've pretty much decided that I will use an automotive engine as the base for the replacement. I plan to replace the cam with a marine cam and I'll put brass freeze plugs in it. I also know that I will need an electric fuel pump if I go with a 92' or later engine. The current cam and crank are damaged from being run with water in the oil so there's not much left worth working with. <br /><br />My question is what years of engine can I get away with using most of my externals including exhaust?<br /><br />I know that I will need a different intake manifold if I go with the vortec's.<br /><br />I'm looking at a 2003 engine with 20K miles on it. Will my current exhaust bolt up? Can I use my distributor? I'll probably run the current 2bbl carb so I know I'd need an appropriate manifold. What about the accessories? This engine is stripped of all externals. Can I use the old brackets and accessories if I change the crank pulley to a V-belt? <br /><br />I know these engines changed quite a bit around 2002-2004 but I'm not very sure about the specifics.<br /><br />Thanks for any help.

 

[Bondo]

Re: 4.3 L automotive engine

To the Best of My Knowledge,.....<br /><br />Other than the Changes in the Intake Manifolds,.....<br /><br />All of Everything else,...... Should bolt right up.....<br /><br />I Know the Exhaust Manifolds Are the Same.......

 

[Silvertip]

Re: 4.3 L automotive engine

Have you contemplated keeping the injection setup? Use the truck computer and you could even add a hypertec power chip and run it on the highest power setting. The truck engine would have close to a marine cam. You would need to add a fuel return line to the tank but that wouldn't be a problem. I've not seen this done but if it were mine, I'd certainly give it some thought.

 

[AlfaRs]

Re: 4.3 L automotive engine

Bondo,<br /><br />Thanks for the info. If it's that easy than I'll probably go for it. The price is great.<br /><br />Upinsmoke,<br /><br />The long term plan would be to put an aftermarket injection system on it. The problem with using the current computer would be the OBD II. I think it would run in limp home mode without either O2 sensor in the system.<br /><br />If you don't know about OBD II, around 2002 they had to incorporate a second O2 sensor after the catalytic converter. This measured the efficiency of the cat and adjusted the injection system to optimize emissions.<br /><br />I'd shoot for the aftermarket system now but I don't know how to get an O2 system into the exhaust system. Any suggestions?

 

[Silvertip]

Re: 4.3 L automotive engine

I would think you could us an ECM from a '92 Astro. Had only one O2 sensor located before the cat. Hadn't thought about the exhaust manifold situation but when any GM engine intially starts, the O2 sensor is out of the loop and the engine doesn't limp. The ECM keeps the converter clutch from engaging until the engine temp gets to about 100 degrees or so and it then cuts in the O2 sensor. Like any electronics, they can generally be "fooled". Anyway, it was just a thought.

 

[AlfaRs]

Re: 4.3 L automotive engine

Upinsmoke,<br /><br />You are correct that the ECM cuts the O2 sensor out of the loop (open loop) during warm-up. The problem is that it runs a little rich and has to run a pre-programed map with no dynamic adjustment. Throw in a different cam and the engine will probably run ok but will never run it's best. That's why I want to go with an aftermarket programable system. Of course I'll never be able to tune it worth a damn without an O2 sensor. <br /><br />Do the MPI engines use an O2 sensor? Are the manifolds different?<br /><br />Thanks,<br />Dave

 

[seahorse5]

Re: 4.3 L automotive engine

Be aware that there are Federal Laws regulating what kind of fuel systems and ignition systems can be used in gasoline powered boats. Most automotive components are not safe in a boat.<br /><br />In a nutshell, fuel systems have to withstand a 2.5 minute direct flame and cannot vent into the atmosphere. <br /><br />Electrical items have to be spark proof or able to contain a vapor explosion internally at least 50 times without igniting a surrounding explosive vapor.<br /><br />Ignition parts also have to meet certain specs.<br /><br />You can view these regulations under Title 33, Part 183 of the Code of Federal Regulations.