Question about Long (20") vs XL (25") shafts...

[pjbrownva]

I have an old 1992 ProCraft 180 combo (the fish and ski) with a 150 HP merc and
a CMC PL-65 Electro Hydraulic Jack Plate. The hull is a bit heavy, and doesn't lift up out of the water
the way many of the true bass boats do.

I've been thinking of upgrading my motor to a Direct injection, and going up to 175 HP as well.

I currently have a 20" shaft, but I see lots of used motors with 25" shafts.

My question is this... can I use a 25" shaft engine with my setup?

If so, what are the trade-offs? Would it be better or worse?

My jack plate has a 5 1/2" set back, and allows for a total of 8" of vertical adjustment (It gives 5" of vertical travel with 1-1/2" of adjustment on the motor bracket and 1-1/2" of adjustment on the transom bracket, for a total of 8” of possible adjustment.)

So I should be able to adjust for the 5" longer shaft, and still have 3" more play.

Once I make these adjustments, I know that would mean that a 25" shaft engine, would (essentially) have the motor and the weight of the motor 5" higher than with the 20" shaft, but what does that REALLY mean? Would it give me more bow lift, and if so, couldn't that be a good thing?

I'm curious for any insights that people can share.

-Philip

[pjbrownva]

(Removed duplicate post)

[pjbrownva]

Here are some photos.

[pmgoffjr]

NO NO NO NO NO
Let me try to be perfectly clear. NO

From personal experience it won't work. No jack plate or other mods will make it run right. Even stacking plates and getting what you think is the right height still won't work.

[cajunrgfm]

IMHO,you can easily just update that old 2.0 liter powerhead,and get a 2.5 150 xr6 or an efi,that would give you the punch to get on pad,,all you need is a powerhead and a tuner adapter,then you can keep your mid and lower unit,much cheaper than a new motor. plus there is still a market for a good running used 2.0 liter 150.

[pjbrownva]

NO NO NO NO NO
Let me try to be perfectly clear. NO

From personal experience it won't work. No jack plate or other mods will make it run right. Even stacking plates and getting what you think is the right height still won't work.

Thank you. I'll consider the issue dead.

IMHO,you can easily just update that old 2.0 liter powerhead,and get a 2.5 150 xr6 or an efi,that would give you the punch to get on pad,,all you need is a powerhead and a tuner adapter,then you can keep your mid and lower unit,much cheaper than a new motor. plus there is still a market for a good running used 2.0 liter 150.

I like your thinking... but I am a newbie at this... that's not to say that I'm not mechanically inclined, it's more to say that I don't know enough about what can be put together and how.

Is there a good resource for me to learn about some of these different options?

Truth be told, I blew the 2.0 L mariner in the photos. One of the cylinders is bad, and the prop shaft was bent.

So, I bought a 1989 Mercury 150 that has electrical problems, and I'm in the process of rebuilding it. The motor has good compression on all Cylinders,
and I am slowly rebuilding it by replacing all of the electrics from my (newer) 2.0 L mariner.

None-the-less, I would love to soup-up an engine to get more power out of it. Is it possible to increase power AND get better fuel economy,
or are the two really incompatible goals?

Any advice or references to where and how i can learn more would be appreciated.

Regarding the 20" to 25" replacement.... message heard loudly and clearly... I won't try it.

Thank you for saving me the head ache and wasted time of heading down a fool-hearted path.

-Phil

[cajunrgfm]

No unless you have a machine shop dont consider messing with the old 2 liter.you really would be best suited finding a mercury 2.5 liter instead of hot rodding anything,150/175 powerheads are still plentiful and will bolt right up to your existing mariner framework and bucket cowling.

[cajunrgfm]

Too bad you werent closer i have a complete 2l 150 running mariner and a couple 2l 150 powerheads with broken blocks but have the late style electrics, and some good pistons and rods left in them.