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Manimum and Cruizing RPM for Ford 50 and Stringer 800

T

texun

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"All,
I have a '76 24&#3

"All,
I have a '76 24' Fiberform Flybridge model with a 5.0/302 and a Stringer 800 outdrive. Recently purchased and repowered. As I am new to the I/O setup, I have no idea what is the correct RPM for this configuration.
I took it for its "maiden voyage", and top end was 3800 RPM, and cruized comfortably at 3100. The mechanic that put it in said this is low, and should operate betwee 4200 and 4600. Is this correct? I know this is high rev for my truck, and just going on that principle.
All help deeply appreciated,
Texun"
 
"Sounds like the mechanic is r

"Sounds like the mechanic is right, but don't know if you want to chase that extra rpm. What was the speed like at 3100 and 3800. Some times people put props on to get certin performance. And they don't care about top rpms."
 
"Thanks for the reply capt.

"Thanks for the reply capt.

Have no speedometer, and no gps at this early stage, and kinda hard to judge. My guess, as I ran next a cattle boat on the way back in and outran it at the 3100 RPMs, so I am estimating a little above 15 mph,,, maybe 18."
 
"Also, would like to have a fe

"Also, would like to have a few mph out of it. If the engine is designed to handle a cruizing RPM of 4200, I would think that would add another 5 mph or more. Is that a good estimate?"
 
"At first look I'd say you

"At first look I'd say you should be able to run 24-28 mph at around 3200rpm to 3600 rpm with the right prop. Kinda looks like it may have been prop'ed down for fishing slow. Check around a little, talk to a prop shop, or Try Michigan Wheel Props, web site might be able to get info on what to use. Also as a starting place see if you can find the markings on the prop you have now as to its pitch."
 
"Just What Prop is on it Now,.

"Just What Prop is on it Now,..??...

If you keep Lugging that motor like That,......

Detonation will burn Holes in those Brand New Pistons......

Listen to your Mechanic,........"
 
"Been lurking around thisdiscu

"Been lurking around thisdiscussion, and feel for a small comment.
The engine is BIA rated at a max rpm to be used max 6 min in one hour! That means max 4200-4600 for 6 minutes.
Max allowed cruising rpm is max rpm -10% of max rpm. In other words the cruising rpm should not be above ca 3900. What speed You obtain is not relevant as for the engine, that depends on the boat.
Stay within the above, and You have a hope that the engine may last.
However, be sure You get Your engine to reach the max rated rpm range first!"
 
"Thanks for all the input folk

"Thanks for all the input folks. Some really good information here.
Looks like, at the least, I should replace the prop to get the recommended RPMs out of the engine no matter the desired speed. At least when I cruize at 15 - 20 mph, it will be at the proper RPM and will get the maximum logevity and performance out of the engine.

Thanks again,
Texun"
 
"Your mechanic is quoting wot

"Your mechanic is quoting wot specs for newer chev v8`s. The older 305 and 327 chevys and all the ford 302 and 351 are rated at 3800 to 4200.
I also have a 24 foot fibreform (pic at left)only with the 351 instead. It`s wot is 4000 on the button at 37-38 mph. Your motor is rated at 215 hp and mine at 233 so there shouldn`t be that much difference in performance.
I find that the boat seems to cruise well at 3200, and gets me anywhere between 25 and 32 mph depending how I trim it out for existing water conditions.
All wot rpms I quoted are straight out of the seloc manual."
 
"Hi all:
I'm new to this

"Hi all:
I'm new to this website but it sure looks like a useful onme with lots of helpful info available. I too have an older 23 ft Fiberform with a 351windsor and electric shift stringer model outdrive (not sure of the model number at this time). I cruise comfortably at 3200rpm and my gps says anywhere from 24 to 30 mph depending on the number of people on board and how the trim tabs are set. These drives seem to work well if treated gently (no pulling skiiers out of the hole etc) 15-20mph at 3200 rpm sounds slow to me, you may want to re-prop.
Happy boating!"
 
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