1998 wellcraft 240 SE 5.7 issues Prop Or engine?

[jws123]

I have a 1998 wellcraft 240 SE with a 5.7 merc 2 barrel and alpha 1 gen 2 with a 17 pitch prop. I got this boat last year was a pain to get it running but now it runs good but i seem to have a have a issue not sure if its prop related or engine related.

OK so its hard to get it up on plane i have trim tabs it helps but to get it to flop over and go i have to hit 3200-3500 rpms and then it will kick in and go my top speed is like 25mph at 3900rpms seams a bit sluggish to me. Next time i take it out i am going to see if i can hit WOT probably cant but il try dont want to blow it up.. I dont know if this is a prop issue or engine issue it runs/idles good doesnt stall or anything i know for a fact that the timing was messed with but it runs good? could timing have anything to do with this issue? if not what prop should i try?

Any suggestions appreciated.

 

[porscheguy]

FWIW, you can go to the owners section at the Wellcraft site and see info on your boat. They list performance data for ‘98. With the 5.7 EFI, running a 15P aluminum prop, they topped out at 43mph @ 4450 RPM.

so they’ve got an extra 50HP and they’re running 2” less prop pitch. And they’re barely propped right. with your 17, you’re severly overpropped. At a minimum, you need to come down to a 15p, and probably a 13 would be best.

as far as accelerating goes, it’s normal to give it full throttle and then pull it back to cruise speed rpm as it climbs out of the hole. One thing you need to do is play with your trim tab adjustment. If you run the tabs in the full down position to take off, you’ll need to back them off some when you climb out or else they’ll cause excess drag. Right now you’ve got somewhere between 35 and 40% prop slip which is way high even on a boat like yours.

1. You can get a Quicksilver Black diamond prop in a 16X14P for $90. They also make 16X13P and I think 16X15P. All priced the same. I’d try a 14P. (I assume you’re using aluminum and prefer to stick with it?)

2. When you accelerate, start out with tabs all the way down/bow down (it takes 5 seconds for tabs to go from all the way up to all the way down if they’re working properly.). Outdrive should be trimmed all the way in/down. FULL throttle.

3. As you climb out of the hole, pull your throttle back to cruise rpm. Trim your drive out and raise your tabs (bow up) gradually until you find the sweet spot.

4. Buy an edelbrock 1409 and 4 barrel intake to find an extra 40-50HP.

 

[Scott Danforth]

something doesnt sound right power wise. most 5.7's are running 19p or higher. heck my 5.0 ran a 19p and pushed 4200# worth of boat around at just shy of 50

first and fore most, get the timing within spec

check to make sure your running on all 8 cylinders, pull a plug wire one at a time to make sure all cylinders are firing.
visually check your flappers
make sure your throttle cable is adjusted correctly

also look at the stickies for other reasons of low WOT.

 

[jws123]

FWIW, you can go to the owners section at the Wellcraft site and see info on your boat. They list performance data for ‘98. With the 5.7 EFI, running a 15P aluminum prop, they topped out at 43mph @ 4450 RPM.

so they’ve got an extra 50HP and they’re running 2” less prop pitch. And they’re barely propped right. with your 17, you’re severly overpropped. At a minimum, you need to come down to a 15p, and probably a 13 would be best.

as far as accelerating goes, it’s normal to give it full throttle and then pull it back to cruise speed rpm as it climbs out of the hole. One thing you need to do is play with your trim tab adjustment. If you run the tabs in the full down position to take off, you’ll need to back them off some when you climb out or else they’ll cause excess drag. Right now you’ve got somewhere between 35 and 40% prop slip which is way high even on a boat like yours.

1. You can get a Quicksilver Black diamond prop in a 16X14P for $90. They also make 16X13P and I think 16X15P. All priced the same. I’d try a 14P. (I assume you’re using aluminum and prefer to stick with it?)

2. When you accelerate, start out with tabs all the way down/bow down (it takes 5 seconds for tabs to go from all the way up to all the way down if they’re working properly.). Outdrive should be trimmed all the way in/down. FULL throttle.

3. As you climb out of the hole, pull your throttle back to cruise rpm. Trim your drive out and raise your tabs (bow up) gradually until you find the sweet spot.

4. Buy an edelbrock 1409 and 4 barrel intake to find an extra 40-50HP.

I was going to try a 15 pitch prop first will see if i can borrow one and right now mine has a 15 DIA prop 16 dia would be better?. And yea i put trim tabs bow down then back up once i take off but still hard to get it up especially with people on it 5 people forget it no way i can get it up. As far as 4barrel setup i was goin to switch last year but dont have the $$ atm but i have heard alot of people say its not worth switching to a 4barrel because they didnt notice a real difference.

 

[jws123]

something doesnt sound right power wise. most 5.7's are running 19p or higher. heck my 5.0 ran a 19p and pushed 4200# worth of boat around at just shy of 50

first and fore most, get the timing within spec

check to make sure your running on all 8 cylinders, pull a plug wire one at a time to make sure all cylinders are firing.
visually check your flappers
make sure your throttle cable is adjusted correctly

also look at the stickies for other reasons of low WOT.

I noticed that some 5.7s are running higher pitch but i guess it depends on the boat?

what do you mean by visually check your flappers?

I just ordered a timing gun and will make sure its 100% i only had the old style gun.

and yes its running on all cylinders idles/runs smooth

I will double check throttle cable to make sure.

 

[Scott Danforth]

the exhaust flappers are in the y-pipe. if there was any over-heat, they tend to drop the flapper leaves down the exhaust effectively plugging the exhaust and the motor only makes about half the power.

 

[jws123]

the exhaust flappers are in the y-pipe. if there was any over-heat, they tend to drop the flapper leaves down the exhaust effectively plugging the exhaust and the motor only makes about half the power.

had outdrive off when i did bellows before it went into the slip this year didn't see anything but if all else fails its worth a check i guess..

 

[Scott Danforth]

have you done a compression test?

 

[jws123]

have you done a compression test?

when i got it last year i did don't remember the exact numbers but they where all pretty close didnt find 1 cylinder that was drastically lower or anything any idea what compression is suppose to be for a 5.7 i lost my book? i can re check again.

 

[Scott Danforth]

Mercruiser manual has cranking compression numbers in the 150psi range

 

[porscheguy]

Scott, go reread his first post.
1. He’s got a boat that weighs 4500lbs.
2. It has a 5.7 w/2 barrel carb. These are rated at around 210-220HP. Not much to push 2+ tons of cast iron and fiberglass through the water.
3. His prop slip numbers are sky high and he’s overpropped.

even when Wellcraft did their in house performance testing on the boat, they used one with fuel injection and a numerically lower pitch. Even with that, they still barely got the boat into the proper rpm range, but they did get much higher speeds.

 

[slag]

I can't find on the wellcraft site where it gives information on 1998 boats. Looking under owners section there are 4 sections, none of which are for a 1998. I'm asking because I also have a 98 wellcraft 5.7 with the VP outdrive and wanted to get more info on it. Owners manuals skip from 1996 to 2000, no 1998 info there, model year catalogs are for the last 4 years, and product info guides are not about 1998 models at all. Help please??

 

[jws123]

Scott, go reread his first post.
1. He’s got a boat that weighs 4500lbs.
2. It has a 5.7 w/2 barrel carb. These are rated at around 210-220HP. Not much to push 2+ tons of cast iron and fiberglass through the water.
3. His prop slip numbers are sky high and he’s overpropped.

even when Wellcraft did their in house performance testing on the boat, they used one with fuel injection and a numerically lower pitch. Even with that, they still barely got the boat into the proper rpm range, but they did get much higher speeds.

Found a few lower pitch props i am going to test it but of course my trim motor just burnt out half way up this weekend :mad-new: so gotta fix that first boats in the water so i would need to get outdrive back up so i can change prop.

Next year i am going to drop a 4 barrel setup on it but its already killing me in gas with the 2 barrel lol.

 

[porscheguy]

Remember, the 4 barrel is only a 4 barrel when the secondaries open.

 

[porscheguy]

I can't find on the wellcraft site where it gives information on 1998 boats. Looking under owners section there are 4 sections, none of which are for a 1998. I'm asking because I also have a 98 wellcraft 5.7 with the VP outdrive and wanted to get more info on it. Owners manuals skip from 1996 to 2000, no 1998 info there, model year catalogs are for the last 4 years, and product info guides are not about 1998 models at all. Help please??

Check the product information guides. I found your boat info with the merc 5.7 in about 2 minutes.

 

[slag]

Well crud.. The browser I used at work didn't show that there was a drop down box to select the year. I did this with another browser (chrome)and can see the drop down arrow. Thanks!

 

[jws123]

Check the product information guides. I found your boat info with the merc 5.7 in about 2 minutes.

wasnt able to find a 15 pitch prop to borrow ..,. just guna order one or try to pick one up locally so far i have the option of
15 - 1/4 x15 prop or 15 - 1/2x 15 prop what size should i get? i looked up what my boat had stock and it was 15 - 1/4 would it make a big difference if i went to 15 - 1/2 dia?

 

[porscheguy]

It doesn’t much matter.

 

[jws123]

It doesn’t much matter.

ok thanks managed to pick up a 15 - 1/4 x15 prop i mean thats what it had stock any ways according to the website no one had the 1/2 available. hopefully this helps will find out tomorrow

 

[porscheguy]

Let us know what happens.