Questions about OMC 3.0 to OMC 5.0/5.7

[TwoBallScrewBall]

Hi all,<br /><br />Just got back from the maiden voyage on my 1988 Bayliner 1950. Good news is it floats. Bad news is it had a rod knock which turned itself into a hole in the side of the block before I could putt back to the dock so my boating season started and ended in 1 day. <br /><br />I got the boat for peanuts so I want to replace the engine since I got the boat and trailer so cheap (now I know why!). Looking for a used or rebuild engine. Where should I start looking and what should I expect to pay. I will do the install myself, just need the motor. <br /><br />What would also be involved in swapping the 3.0 for a 5.0 or 5.7 V8 since I'll be pulling the engine anyway? The outdrive is an OMC Cobra. <br /><br />Thanks all.

 

[TwoBallScrewBall]

Re: Questions about OMC 3.0 to OMC 5.0/5.7

Nobody??

 

[TwoBallScrewBall]

Re: Questions about OMC 3.0 to OMC 5.0/5.7

I did some investigation and also have the OMC manual. The removal of the 3.0 seems simple. I'm used to pulling car engines, this looks a lot less involved. Basically disconnect wiring, fuel, water, and there are three mounting bolts. Hoist it out and that's it. If I can get my hands on a complete 5.0 or 5.7 OMC engine, maifolds, ocupler, mounts, etc, is it a big project to drop it in if it originally had the 3.0? Also, my dad had a robalo with a version of the 3.0 that was rated at 190hp. He said it was the same engine with a hotter cam and aluminum heads. Is this available anywhere? Lots of questions, first boat! What I can get for a reasonable price will dictate what I replace my newly religious engine with (get it?).

 

[CCrew]

Re: Questions about OMC 3.0 to OMC 5.0/5.7

You do realize that you technically should be replacing the outdrive also, correct? 1988 3.0 is pretty different mechanically from a 5.0/5.7 or even a V-6. 5.0 uses a 21:17 top gear case, a 5.7 uses the 21:16. Most 3.0's use 21:19's. End result is that the final drive ratios are totally different. <br /><br />That said, the 5.7 certainly fits in the boat. Mine had a 5.0 originally and is repowered to a 5.7. If you need dimensional info as to whether the mount placement, etc is the same feel free to contact me. There were a couple of full powerplant setups recently on eBay so they're out there.<br /><br />Regards,<br />Roger

 

[Skinsk]

Re: Questions about OMC 3.0 to OMC 5.0/5.7

If the OMC 3.0 is anything like the mercuiser 3.0, then you will have to build two new motor mounts for the 5.0l.. <br /><br />The 3l uses one singe front motor mount in the center, while the 5l has two front motor mounts on each side..<br /><br />Plus the V8 is a lot wider, so make sure you have room back there..<br /><br />Scott..

 

[tylerin]

Re: Questions about OMC 3.0 to OMC 5.0/5.7

I have a 4.3 chevy v-6 and it has the 21:19 gear ratio, more than likely same as yours. CCrew is right on w/ what he says about the change w/ ratios.I've had the 4.3 for the last 16 years and it has performed fine. 18ft boat, top end, 46mph on glass, not a struggle to get on plane. Just another option to the V-8. Times I wished I had the V-8 but am happy I don't have the 4 banger

 

[Northern Eclipse]

Re: Questions about OMC 3.0 to OMC 5.0/5.7

Going from a 4 banger to a v-8 is going to be alot of work in 1988 bayliner, asides from outdrive gear ratio, that bayliner will need to have the proper engine stringers glassed in,that not such a big issue as long has the exsisting stringer/floor/ transom are good ...

 

[TwoBallScrewBall]

Re: Questions about OMC 3.0 to OMC 5.0/5.7

Yeah I have decided to keep it simple and drop in a new 3.0. I spent the evening last night draining the antifreeze, rainwater, oil, gas, and any oher mystery liquid that accumulated in the bilge in the last 3 days. Filled a 55 gallon garbage can. Sprayed down the engine compartment and engine with degreaser and got it looking pretty good, just wanted to minimize the mess when I do pull this thing out of there, hopefully this weekend. This will be my first boat engine pull-out, I've done cars before but this looks easy in comparison. The hardest part for me will be disconnecting the wiring and labeling it up so I can put it all back together. Once that's done it looks like 2 nuts and 2 lag bolts and it's time to hoist it out. <br /><br />I just want this thing ready for april, and in addition to the engine I also have a bit of vinyl/upholstery to replace. If I end up getting involved in the V8 swap I know I will go beyond schedule. <br /><br />Anyone have a 3.0 long block, preferrably low hours (haha) that they want to sell. I'm in NJ and could drive a reasonable distance to get it.