86 18' dixie, 4.3 21p prop...35 mph?

[mwe-maxxowner]

I'm looking at a nice clean '86 dixie hustler 188 ski boat with a 4.3 mercury v6. In good shape and has a wake tower.

My question is, with the 4.3 and a 21 pitch prop, shouldn't I get more than 35 mph? I get up to about 3800 rpms. This is while playing with the trim. I trim up and it speeds up, until I hit about 35, then the prop starts to cavitate. The motor cranks easily and idles nice and smooth. Doesn't sound to be missing or stuttering, and takes off strong.

I have a friend with a '99 bayliner capri 1750 18' that has a 3.0 4 cylinder with an unknown prop ( we can't find anything stamped on the prop). I'm assuming it's whatever was stock though, the bayliner was bought with almost no hours completely stock from an 80 year old man. We have hit 43 mph in his with the 3.0, and it takes off nice and strong as well.

My prop has 1918p21 stamped on it. If 35 is all it should run, I can live with that, but if there is more to get I want it! The boat is nice and solid, no rot, no waterlogging, and we had 2 180 lb guys on board with nothing else.

I had a similar boat with a 150 two stroke on it that was a rocket, I think it spoiled me lol. I didn't, however, expect a similar boat with a 3.0 to outrun me. I don't think my rpms indicate I can go up any more on the prop. Is this just 13 years more innovation at work?

 

[emoney]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

Hull design definitely comes into play, but I'd ask to have this thread moved to either the "Prop" forum or the Mercruiser I/O forum. Sometimes the "experts" don't leave those forums and may not see your question. Just a thought.

 

[kenmyfam]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

3,800 rpm at WOT seems low. You may be over propped at 21" pitch.

 

[jestor68]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

A 26 year old motor can be pretty worn out and still run smooth. Do a compression test to see just how worn out it is.

In the mean time look for a 17" pitch prop to put on it get your rpm up where it belongs( 4400-4800 rpm ).

A Solas Rubex 17 pitch would be the best bang for the buck. That would put you at about 4600 rpm and pick up several mph as well.

After you put in a new long block, you'll be able to run that 21 pitch and rip past your buddy's Bayliner doing 50+.

 

[spoilsofwar]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

As has already been stated, you are coming up well short of recommended WOT RPM range. Could be too much prop pitch, or could be something more serious. Is the outdrive original to the boat?

 

[Howard Sterndrive]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

http://forums.iboats.com/showthread.php?t=295070

your issue will be on that list

 

[mwe-maxxowner]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

As far as i know, outdrive is original. Think a 19 degree prop would do better? Might have access to one of them cheap. There is a little growth of some sort on the outdrive, but not the hull from sitting in the water. If timing was off, it wouldn't idle well, right? How can I check for throttle opening all the way?

 

[Howard Sterndrive]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

If timing was off, it wouldn't idle well, right?

no. Not much makes a 4.3 idle smoother than retarding the timing. Timing also needs to advance as engine rpm increases. Flyweights in the distributor make this occur at higher rpm. Those weights love to get gummed up with 25 year old oil residue and stick in the idle position.

How can I check for throttle opening all the way?

look down the carb while someone works the throttle

you can change props if you want. waste of time in my opinion...clean the flame arrester at least first... get out the elbow grease

An 18' boat with a 4.3 should be able to muscle it's way around the wrong prop (by 2"P) to better than 35mph.
you need to diagnose it.
You don't put smaller wheels on a car that needs a tune-up. You tune it up.

compression test it
weigh the boat or look for waterlogged floatation foam - or even squatting trailer tires can be a clue that you have a water retention issue
fuel pressure

I'm just reading that list now...

 

[mwe-maxxowner]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

if over propped' i wouldnt have a good holeshot, would i? i have a friend with an 07 4.3 21 prop that runs 55. i just want 45 lol! can someone move this thread?

 

[mwe-maxxowner]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

so try a new distributor?

 

[Bondo]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

so try a new distributor?

Naw,... Just do a Full Tune Up, 'n Service, along with a Compression test, to see what's up...

 

[Howard Sterndrive]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

so try a new distributor?

check the advance weights.. unless you see broken parts- brake clean, a toothbrush and spray lube all you'll need there

 

[mwe-maxxowner]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

Ok. To see if it's purchase able I'll check compression and check the foam. Won't do anything else unless it's mine.

 

[mwe-maxxowner]

Re: 86 18' dixie, 4.3 21p prop...35 mph?

It feels light behind the truck, as much or lighter than my friends bay liner. How much should I expect it to weigh? Has two swivel seats, a bench in the rear, tower, and tower speakers. I have a local scrap yard where I can weigh it, but on the trailer, of course.

What should compression be?

I know I should be able to get more, I just want to be sure it's not a dying motor or rot/waterlogged foam before I buy. I have two months to pay.

Timing, carb, prop, etc I can handle. Even if it needs a new carb, but I don't think that's the case. Doesn't miss a beat seems to run nice. I would guess throttle not opening fully or water logging if I had to guess. Though it doesn't seem heavy, no other choices seem likely. Is there a way to manually open throttle by hand on the water?

Very similar to my old Dixie but it had a 150 outboard with 19 pitch. Half rotten and it would fly lol

I read the list, but I know nothing about the flame arrestor. How much is a fuel pump for this thing? What pressure should I look for if I test for that?