enemic mercruiser 5.0L 2V

[monterey242]

Hey all,

I've got a monterey 242 cruiser w/ an enemic chebby 305 2v. I'm not one for going fast when on the water (i've got my cobra for that), but if I have 4 or more adults on her, then she is a real dog off the line... and i mean a REAL dog. I need advice on two trains of thought here on how I can improve the performance just a bit:

PS: some more facts: Bravo 3 dual stainless props. And if memory serves me correctly, at WOT, she clocks about 4100rpm at 40mph (with only two on board and 1/2 tank gas).

I'm thinking of:

OPTION 1: Upgrading to a 4V edelbrock intake and carb. I know its not major power enhancement (guessing 20bhp), but I'd hope the 4V should improve 'off idle' response (as well as a couple of MPH on the high end)

OPTION 2: A prop 'pitch' change. Like gearing a car, i'm thinking it would improve the holeshot a bit (but at the expence of revvs & MPH on the high end)

OPTION 3: Do both...

In theory, these seem reasonable upgrades, but my real world experience in this area is lacking...

Advice please....

 

[monterey242]

Re: enemic mercruiser 5.0L 2V

11 views and no opinions? Come on now, this is 1st grade stuff for you pros. I know i'm a noobie on these forums...so help a brother out...

 

[skeat]

Re: enemic mercruiser 5.0L 2V

It sounds like you are over propped. I would find out what the operating range is for your engine, which I would think would be somewhere around 4800+ rpm. If that's the case a lesser pitch would definitely improve your "out of the hole" performance and might even give you more top end because you won't be boggin down the engine while spinning more rpms. If you opt for the 4bbl carb manifold upgrade I wouldn't do anything with the prop until after the modification because all numbers change regarding prop selection. I think for every inch of pitch your rpm changes by 200. So if you know what your running now, you can use that as a gauge. Anyone (reputable) you buy the prop from should be able to guide you through the process.

Of course this applies only if your engine is running well. If it's not performing right because of an engine malfunction that would have to be taken care of first.

 

[Haut Medoc]

Re: enemic mercruiser 5.0L 2V

Hard to say if you are over propped when ya don't say what you are running......
4100 is low WOT.......
24 feet is a lot of boat for a 305.....
But, I'd say you are over propped & under powered....
The extra hp a new 4 bbl & a new intake will provide won't hurt a bit in this case......​

 

[QC]

Re: enemic mercruiser 5.0L 2V

I agree with skeat and Haut Medoc, but we need to back up a little first . . .

1) Need to confirm that your wide open throttle (WOT) numbers are accurate. Tach must be right and GPS for speed.

2) History of the boat. Has it ever had better hole shot with these same props? Faster? Did you own her new?

3) Last tune-up?

4) Condition of the bottom? Is she trailered or slipped?

Your WOT spec is probably 4400 - 4800. Need model year, but that should be close. If you pitched to get toward 4800 you will improve your hole shot, and if your 4100 is correct your top speed as well. 40 MPH though indicates a pretty decent running 5.0 in that boat, so I think we should work on getting the numbers right first . . .

 

[thrasher]

Re: enemic mercruiser 5.0L 2V

There is also no point in tuning an engine that is in poor condition. Not saying your is, but you should run some basic tests (compression, etc) just to check that you are starting with a healthy motor, otherwise you are just throwing good money after bad.

It also sounds like you need less pitch on your prop. Have you checked the ignition timing and valve clearances?

Gary

 

[monterey242]

Re: enemic mercruiser 5.0L 2V

Thanks alot for the responses guys. I'll attempt to provide a little more background on myself and my boat:

I'm a decent backyard mechanic and run a 2001 mustang Cobra at Open Track events. I'm pretty technical with cars but boats are new to me. I run my cobra hard to 7k on a regular basis. The point is that i'm generally all over driveline specs /temps/revs/oil pressure and the like:

The boat: The car is about me, but the boat is about my family. I'm a new/first time boat owner and I love it. I live off of Lake St. Clair in MI. I wanted a cruiser for family fun, but wanted a smaller one so I could trailer to inland lakes and to Lake Superior (which I visit twice a year).

I bought a 1998 Monterey 242 crusier with 130hrs on her. she was a trailer queen before I bought her and looks brand new. She has never sat in a slip. I got a great deal on her and the former owner cut me a large check to take it...

The only bummer was that it was a 305 and not a 350 (like the other one I was looking at), but the boat is in perfect working order (compared to the others) and since speed was not originally on the 'docket' I went ahead w/ the purchase. I currently store her in an "In & Out" rack storage (at a very nice marina). The plans for her include family fun, and maybe just a little more kick down low (but i always hate to sacrifice top end)...

More Info:
* she weighs 4500lbs (I dont know if that's wet or dry)
* I dont know the 'pitch' angle as of yet.
* On a smooth day, with a light load, she'll hit about 43mph...tops.
* I checked the WOT & RPM's before, but I dont believe it could have been over 4200rpm's... (i wont be able to check that again until the spring since she's already in winter storage mode)...

more:

* I havent' personally tuned the engine yet because the original owner paid $300 for a full tuneup the season I bought her (even though the boat hadn't been legally stickered since 06'), but with that said, she runs great. But every once in a while, if I hit the throttle hard from almost a dead stop, I'll get a bit of a pop from the bilge (which i had taken as a small backfire thru the carb). I could be wrong, and its only happened twice.
* I've owned her since July of this year and have had her out about 20 times. She generally runs very well...
* The bottom of the boat is like new. And the lower unit manufacturers stickers are still present believe it or not. I would have thought they'd have washed off a long time ago...

thanks for all the responses... keep em' coming...!

 

[QC]

Re: enemic mercruiser 5.0L 2V

Well, if she is truly getting the 40+ MPH, she is pretty close if not excellent on power. Again, if your RPM is right you stand to gain both hole shot AND top speed with the correct pitch.

Define "real dog". How long to get on plane?

 

[Haut Medoc]

Re: enemic mercruiser 5.0L 2V

Sounds good to me, too.....
Again, 24 feet is alot of boat for a 305......
I think you are expecting too much from it.....
You may need to sacrifice top end for the hole shot by propping differently.....
There is no substitute for CI.....​

 

[monterey242]

Re: enemic mercruiser 5.0L 2V

Define "real dog". How long to get on plane?

Well a few weeks ago, I took my wife and I (as well as another couple) out to dinner on the water. Once or twice I tried to get on it (from almost a dead stop) and its almost like there is nothing... but once she finally gets going, its almost like some vacuum secondaries kick in and the boat starts moving out pretty good... and yes i know its only a 2V. lol. But there is NO bogging whatsoever. I just think (like you guys) that its alot of boat for a 220hp 305.

I did 'sea trial' the boat before buying, but with just me, the old man, & no gas in her, she hauled arse. So I couldn't really see the lack of performance until the whole family and > 1/2 tank of gas were all part of the daily equation if you know what i mean...

So consensus is a definite pitch change if I can verify the RPM's are below say 4500? If they are above 4500, I'll assume there is no room for change?

And are we in consensus that the 4v + intake is a good bet? Or am I wasting $ on something that will make little if any impact?
And on the note of the 4v setup, are there desired setups to go with? is a treated AL intake an option? Weight reduction is always a good thing...

Chris

 

[QC]

Re: enemic mercruiser 5.0L 2V

So consensus is a definite pitch change if I can verify the RPM's are below say 4500?s

Yes, emphasis on verify.

 

[alaska_av8r]

Re: enemic mercruiser 5.0L 2V

If you find that your WOT rpm's are close to the recommended max then changing pitch will probably be out of the question, one thing you may want to check into which helped me a bit was "porting" the prop. Helps get the prop up to a higher rpm for the hole shot and keep the same top end. Just do a search about it on here, but keep in mind it doesn't work in all situations.

 

[thrasher]

Re: enemic mercruiser 5.0L 2V

I would also look at fitting smart tabs. They will help keep the bow down and will let the boat get on plane quicker.

Gary

 

[QC]

Re: enemic mercruiser 5.0L 2V

Good suggestion Gary. Most cruiser actually have helm adjustable tabs as standard equipment. Does she have tabs Monterey? If so, do you use them?

 

[monterey242]

Re: enemic mercruiser 5.0L 2V

Good suggestion Gary. Most cruiser actually have helm adjustable tabs as standard equipment. Does she have tabs Monterey? If so, do you use them?

Trim Tabs? yes. I use them to stop the boat from listing port or starboard. But I have heard that if both tabs are full 'out', it may help holeshot a bit. But regardless, that's not a solid solution IMHO. Its takes a minute to move the tabs and I shouldn't have to use them in that manner...

 

[QC]

Re: enemic mercruiser 5.0L 2V

Dude . . . Hmmmmmmmm. How do I say this gently? THAT'S EXACTLY WHAT THEY ARE FOR!!!!!!!!!

Full down when you take off, as soon as she starts getting up pull them up a little, use them as far down as you need to to keep her on plane at low speeds too. Yes, they are good to correct for listing, but they are also for anything else good you can do with them . . .

 

[monterey242]

Re: enemic mercruiser 5.0L 2V

Dude . . . Hmmmmmmmm. How do I say this gently? THAT'S EXACTLY WHAT THEY ARE FOR!!!!!!!!!

Full down when you take off, as soon as she starts getting up pull them up a little, use them as far down as you need to to keep her on plane at low speeds too. Yes, they are good to correct for listing, but they are also for anything else good you can do with them . . .

HA! sounds good. See... my noobie colors are flying high... haha. I will take this advice literally.

I've had some of the guys working at the marina tell me to stay out of the tabs whenever possible... that they use up gas and whatnot. I'm not too worried about gas however...

You have all been great help. So now I wait for winter to end up here...

 

[Dakota47]

Re: enemic mercruiser 5.0L 2V

Winter to end?? it has not even began yet..

 

[monterey242]

Re: enemic mercruiser 5.0L 2V

Winter to end?? it has not even began yet..

Unfortunately it is for me (and all at my marina in the 'In & Out'). Our boats have to be in storage mode on 10/1. We are allowed 2 weeks on the maintenance rack and that's it until April 1st... It sux, but I like everything else about the "In & Out"