2004 250 Project Thread

[slideruleracer]

Curious on gxi tune.. was it just for rev limiter? ( yes I'm looking for a couple more)

I sent a merc ecu to whipple (496HO) years ago to help on idle richness as they would leave a ton of soot on the transom.

Have you done a map overlay in the two tunes? And or what was your goal..

Geeze now I'm gonna want new cams.. when does it end??

I haven't done a field by field compare yet, but it's definitely more than just rev limiter. Idle speed looks different and from what I understand the timing is a little different. When I actually get time to peel back the layers of the tune files I'll let you know what I find.

If anybody else is daring enough to take this on, I'll reprogram your ECUs for cheap.

[slideruleracer]

Can you get any shots of what you ported on the throttle body. I wonder how much it helps with the factory tune or does it let too much air in with the factory tune to control it?
That would be a easy thing to do for 20hp. Not sure it's That much though. Are the injectors the same between the gi and gxi? I haven't looked in awhile.

I should have taken more pictures before I put the throttle body back on. It's not your typical intake manifold porting job.. Basically, the botom of the casting is cut off to gain access to the major restriction in the path, then everything is smoothed out and the bottom is welded back on. I'm expecting to have to richen up the tune in the upper RPM region, though others have suggested that adjusting the fuel pressure regulator could accommodate it. I'm not to fond of richening the mixture across the band though.

Here's a thread on OSO that talks about it:
https://www.offshoreonly.com/forums/gen ... 496-a.html

And another on Performance Trucks:
https://www.performancetrucks.net/forum ... 372/page3/

The fuel injectors are the same between the Gi and Gxi. As part of my rebuild, I sent my injectors out to be overhauled, cleaned and tested. As it turned out, according to their test reports, they weren't flowing that poorly before, but at least I know they're good now.

Here's a photo looking down past the throttle body butterfly.

[slideruleracer]

The last few days I've continued to disassemble the transom components, then bead blasted them as best I could in my tiny cabinet. I was able to disassemble everything except for the trim hoses, unfortunately. And to get the forward cylinder pin out, I needed a lot of heat AND my 20 ton press. So, I have a lot of concerns that the hydraulic lines are no longer reliable and had to drop a few C notes to get some new and used lines on their way to me.

I may also rebuild the cylinders themselves.. the heat may have compromised the internal seals.

But, it's apart and the parts are mostly cleaned up from that horrendous salt corrosion. The aluminum around the water intake O-ring on the pivot housing is unbelievable!

My suggestion to all of you salt water folks is to make sure you take those pins out and grease them up at least every year, if possible. Not being able to remove that pin was a MAJOR headache in this disassembly. That and the lines... Volvo didn't leave enough space around the heads to get a good flare wrench on them and being stainless, they're very soft..

[slideruleracer]

Tonight, I recruited my 9 year old to help me build the engine testing dashboard. I've scrounged up some old gauges off ebay over the last couple of months and threw them together on an old piece of sheetmetal. Since I was teaching the youngest, I skipped the CNC and used the drill press and jig saw. I think he enjoyed it.

[cmattj]

Nice work slide!! Love the dragster dash and your boy into what dad is doing! Awesome!

Looking forward to your results and I may take you up on the flash. No wonder outboards seem to be the choice for saltwater.. eeeek

[Big Block Power]

Very cool rebuild. Always fun to watch someone rebuild things.
On that program it would be hard to just dump a gxi tune in and not having the cam. It does idle lower. I guess if you can tune the fuel map to it then yes. Not sure how much playing around that would be. I'm not a tune pro by any means I never did one other than factory stuff.

[slideruleracer]

Today I finished prepping and painting all the transom pieces except for the cylinders. I also took a crack at modifying the old riser to fit a wideband O2 sensor, but the weld filler that I added ended up being harder than my tap.. So I need to work on that process a little more.

[slideruleracer]

Sone more pics.. The zinc chromate is very green..

[slideruleracer]

All of the new bits for reassembly.

[Driller]

Really nice work Slide, I’m impressed.

[Big Block Power]

Very cool lots of pieces. Not a cheap project. Do it right once so you don't have to do it twice.

[slideruleracer]

So, I took another crack at the riser. I machined off the weld material with a carbide end mill and pressed in an insert that I made with the M18x1.5 threaded ID. We'll see how good it holds. I also finished the test dash. Looking to start the engine next weekend....

[The La Salts]

Nice rebuild! Any tips on maintenance. I trailer my boat for every trip and spray CRC 6-56 on everything including the trailer.

[slideruleracer]

Rinse off the salt. Seriously.

Inside and out.

None of the work I've done so far on the outdrive or engine would have been necessary if the previous owners had rinsed off the salt water regularly. And at the end of the season, pull the trim pistons stainless pins out and grease them out (and rinse out the salt). Maybe things like the lines would be more than normal for average folks who aren't comfortable tearing things apart, but even just rinsing off the outside of the engine every now and again would have prevented all of the corrosion to the head and exhaust bolts.

Honestly, other than that, the boat is in great shape for a 14 year old craft. I'm changing a lot because it's what I enjoy, but otherwise, they did try to keep it in good shape... But that damn salt!

[AsLan7]

So cool watching this come together!