Logo
FULL SITE MENU

Prop numbers and speed with a 3.0L

C

changetires

New member
I cant decipher these prop numbers at all. 1985 3.0L 140. Boat runs 32 mph with this prop at 4100rpms. 1.98 outdrive ratio.

tks,

ed
 

Attachments

  • IMG_0706.JPG
    IMG_0706.JPG
    79.8 KB · Views: 31
Those look hand stamped like what a prop shop would put on when it's repaired. Nothing wrong with a repaired prop , just doesn't look like manufacturers numbers . Look on the hub behind the prop nut, usually part number with last two being the pitch

what size boat is it in ? And is the tach accurate? I assume your trying to get a replacement prop or get wot rpms up ?
 
Dieter said:
Those look hand stamped like what a prop shop would put on when it's repaired. Nothing wrong with a repaired prop , just doesn't look like manufacturers numbers . Look on the hub behind the prop nut, usually part number with last two being the pitch

what size boat is it in ? And is the tach accurate? I assume your trying to get a replacement prop or get wot rpms up ?
Click to expand...

......since 4100 max wot rpm is too low for this engine and running that prop, if that is your actual rpm, will eventually damage the engine.
 
Found the numbers Dieter tks. I is currently 15x17 prop.
It is a 1985 Wellcraft 17 foot American. Yes I was looking at getting the RPMs up at WOT.
 
Last edited:
I would verify your tach first as on a 17 ft boat with 17" prop you should be able to get up to 4600-4800 rpm. Is the engine in a good state maintenance wise? Ignition components, carb and fuel filter delivery ok? I would run through some maintenance checks first, is hull clean, do you have water under the floor, or loose exhaust flapper in down pipe.
 
Dieter said:
I would verify your tach first as on a 17 ft boat with 17" prop you should be able to get up to 4600-4800 rpm. Is the engine in a good state maintenance wise? Ignition components, carb and fuel filter delivery ok? I would run through some maintenance checks first, is hull clean, do you have water under the floor, or loose exhaust flapper in down pipe.
Click to expand...

Yes w/Dieter. At a glance your prop seems in the ball park. And extra drag and low power seem likely suspects. Besides the above, make sure your flame arrester screen is clean. They can really restrict air flow if neglected. Do you have experience with this boat? It this a recent problem?
 
Not much experience since I saved it from the landfill. Hull still has barnacle residue from where it sat in salt water for 8 months. This has been a project for the last couple of months. I was trying to get an idea of what to expect.
 
changetires said:
Not much experience since I saved it from the landfill. Hull still has barnacle residue from where it sat in salt water for 8 months. This has been a project for the last couple of months. I was trying to get an idea of what to expect.
Click to expand...

If you got a barnacle encrusted landfill boat to float and run at 32 mph, I'd say you've made a helluva good start.:) Muratic acid won't affect gel coat, and will clean your hull well. Dilute it in a spray bottle 50/50, use rubber gloves, safety goggles and at least a particle respirator. Start on the keel and work up to avoid getting drips on you. If it doesn't dissolve the crud (or fast enough) up the acid %. Keep the acid off any boat metal, and especially the out drive.

Is your engine/outdrive from the salvaged boat? If so you need to be sure you're running with fresh engine oil, and more importantly, fresh out drive lube.
 
I cleaned off the large barnacles with a plastic scraper. Cleaned the flame arrestor with brake cleaner and carb cleaner. New bellows, gimbal bearing, shift cable, shift shoe, shift bellow. Had to rebuild front motor mount box and glass it back in. Put new starter on and ezoutted a broken starter bolt. Changed points to Pertronix and reset timing from 40degrees adv. back to 8 BTDC. I don’t know how it got that far adv.
 
changetires said:
I cleaned off the large barnacles with a plastic scraper. Cleaned the flame arrestor with brake cleaner and carb cleaner. New bellows, gimbal bearing, shift cable, shift shoe, shift bellow. Had to rebuild front motor mount box and glass it back in. Put new starter on and ezoutted a broken starter bolt. Changed points to Pertronix and reset timing from 40degrees adv. back to 8 BTDC. I don’t know how it got that far adv. I have been using muriatic acid on some spots and it does real good. I didn’t want to spend a lot of time on cleaning if I could not get it to run but now we can get to cleaning. Upholstery was in great condition for a 85 model. No rips or tears but a little mildew.
Click to expand...
 
Update on project saltwater recovery...WOT today was 4400 to 4500 trimmed up...speed 35..still using the same prop 15x17..rechecked timing after running at 75% throttle for 30 mins and was at 6 BTDC while sitting at the dock idling at 700 rpms. This was just me in the boat and about 1/4 tank on a 15 gallon tank. Looks like I can get to waxing and finish with the barnacle residue. Cleaned about 60% off.
 
Back
Top