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Author Topic:   Re-power I/O GTX-18
ScottsGTX posted 04-29-2004 01:28 AM ET (US)   Profile for ScottsGTX   Send Email to ScottsGTX  
I have a 1982 18 GTX that came with a MerCruiser 260-HP I/O that needs to be replaced from helm to prop. I am in NH, any advice is welcome.
Curtis Johnson posted 04-29-2004 05:48 AM ET (US)     Profile for Curtis Johnson  Send Email to Curtis Johnson     
I just repowered mine with a 260. I kept checking ebay and found one almost new that a dealer had. He did not get his reserve, but took an offer later. He was willing to install, warrant, and do a water test. Runs great. In retrospect I regret not installing the newer style, smaller starter motor. It's very difficult to get the full sized starter out without lifting the motor, but small was $300 more, so I passed.
Also, I probably should have had the gas hoses replaced, but he wanted $500, and I was feeling nickled and dimed by that point. That may be something I can do, but it won't be easy. You will love the GTX. Fast, smooth, good wake, take six adults in Whaler style.
jimh posted 04-29-2004 08:56 AM ET (US)     Profile for jimh  Send Email to jimh     
[Moved the thread from another forum.]

The easiest re-power is to replace the I/O with a similar MerCruiser, as suggested above. If you are going to be using the boat primarily in freshwater, inboard/outboard drives are very popular. For a given horsepower they are less expensive than an outboard, although their power-to-weight ratio is not as good. But their horsepower-to-dollar ratio is higher.

If you were really motivated and wanted to change to outboard power, you could remove the outdrive, repair the transom, and add an engine setback bracket. This would probably be a minimum of $4,000 in expenses just to repair the boat, buy a bracket, and install it. After that you would be in a position to buy a $12,000 outboard motor, install it, and re-rig the entire boat.

The advantage to the outboard powering would probably be better performance, but it would come at quite a cost.

Probably for less than half of the cost of re-fitting with an outboard you will be able to re-power with a replacement inboard/outboard system. If you are staying in freshwater, especially seasonal fresh water as I'd expect in New Hampshire, the I/O re-powering seems like the best option.

brisboats posted 04-30-2004 11:21 AM ET (US)     Profile for brisboats  Send Email to brisboats     
That motor had a cross over year in 1986/1987, most notable , the rear main seal/ coupler/ valve covers/ and dipstick are different. If you find a sweet deal on a later motor you will need to make a few changes in fitting it out. Good news is the 5.7 small block was/is a popular motor and you should have little trouble finding one.


brisboats posted 04-30-2004 11:35 AM ET (US)     Profile for brisboats  Send Email to brisboats     
Forgot to add there is a second crossover that came with the introduction of the vortec heads, these motors are great motors but have no parts interchange with the earlier versions. I think these came out in 1996.


Bigshot posted 04-30-2004 02:47 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
I would install a new 300 or 320hp Vortec 5.7L roller engine. It will still "bolt up". If you are looking to buy just a short block or a long block, then you will have to stay with whatever generation engine you have being what Bris said. If you are doing a COMPLETE repower sans drive, get the new Vortec with or w/o EFI.

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