1997 215 ec. Can’t get up to speed

Ok another update, I hooked up a digital tach and my wot is 4000 rpm’s at 30 mph couldn’t get passed that. I also confirmed the 14.5 x 19 prop .So it seams I’m 400 to 800 rpm’s shy. So what’s my next move.
 
Mtr727 said:
Ok another update, I hooked up a digital tach and my wot is 4000 rpm’s at 30 mph couldn’t get passed that. I also confirmed the 14.5 x 19 prop .So it seams I’m 400 to 800 rpm’s shy. So what’s my next move.
Click to expand...
You said you're trimming correctly and the hull/running gear is clean and in good shape. So... back to the mechanical issues - see the various posts that have already been made about this (we'd really just be repeating ourselves by stating those things again), focusing first on tune-up items.

BUT... I don't think this was yet mentioned... check your fuel quality. Dump the fuel/water sep into a clear glass jar and let it set for an hour. Take a pic and post it.
 
Was top speed still 26
 
Guys,

He’s got a ton of prop slip. At 4,000 RPM (clean bottom, propeller in good shape, trimmed and etc.) he should be running around 35 MPH +/-, assuming he has the stock set of 1.62 gears.

Theoretical Speed = 4000/1.62 = 2469 RPM at the prop shaft. 2469 (19”) = 46,914”/12 = 3909’/5280 = .74(60) = 44 MPH w/o slip. So, roughly 32 percent slip @ 30 MPH.

For reference, my 230 BR runs somewhere around 40 MPH @ 4000 RPM (not WOT) w/a 1.47:1 gearset and a 19” High Five Propeller.
 
I was hitting 30 on flat water , half tank of fuel also changed plugs . I am smelling seams like a lot of fuel during idle. Could be too rich? How do I check geat ratio?
 
Saw a video on you tube today exact setup guy was doing 47mph.
 
SeaRide said:
Guys,

He’s got a ton of prop slip. At 4,000 RPM (clean bottom, propeller in good shape, trimmed and etc.) he should be running around 35 MPH +/-, assuming he has the stock set of 1.62 gears.

Theoretical Speed = 4000/1.62 = 2469 RPM at the prop shaft. 2469 (19”) = 46,914”/12 = 3909’/5280 = .74(60) = 44 MPH w/o slip. So, roughly 32 percent slip @ 30 MPH.

For reference, my 230 BR runs somewhere around 40 MPH @ 4000 RPM (not WOT) w/a 1.47:1 gearset and a 19” High Five Propeller.
Click to expand...
I like math... but how does this help solve the problem? :) Especially since his prop seems to be about right. And this doesn't take into account the more likely scenario of a mechanical problem, correct?
 
I'll check the fuel tomorrow.
 
MTR. If your outdrive still has the original MerCruiser decal on the upper gear case, have a look at the port side of the drive and it will have the gear ratio labeled as well. Who knows it could have been changed over the years. The only other way is to physically inspect the gears. I really don’t think it’s practical to spin the shaft 1.62 times to see of the propeller makes a full revolution. Typically speaking, small blocks were delivered with either 1.62, 1.5 or 1.47 gears. Also, I assume you are running at an altitude close to sea level????

As far as how does math solve his problem??? Nope it doesn’t :). I simply thought 4000 RPM = 30 MPH is way off. So, I clearly had too much time on my hands and did a little math. Based on the math, you would think, dirty bottom/drive, bent prop improperly trimmed or he’s pushing too much weight, but he’s already stated that’s not it. Wish I had the answer. Wouldn’t 4000 RPM still = a speed of more than 30 MPH even on a weak engine?? Maybe???
 
When was the distributor, rotor, and wires replaced? At ten years the rest of the ignition components should have been replaced. What about the compression numbers. These are not difficult mechanical work and would cost maybe $500-$600 for a shop to do.
 
Mtr727 said:
I was hitting 30 on flat water , half tank of fuel also changed plugs . I am smelling seams like a lot of fuel during idle. Could be too rich? How do I check geat ratio?
Click to expand...
What did the plugs look like? Did you take pictures?
 
I cruise at 28 29 mph at 3200 rpm with a17 pitch stiletto three blade stainless steel prop. Works for me. Prop could be messed up
 
SeaRide said:
Another idea: Have a propeller shop check to see if yours is within spec.
Click to expand...
This. Plus do a compression and leakdown test to rule out the big mechanical things before you start chucking money at it. I had this problem on my old boat. Engine ran “fine” but turned out it had a cracked head.
 
Mtr727 said:
Yup with smaller engine
Click to expand...
But likely same HP as mine was injected (possibly more depending on your rebuild).

Even with the "smaller" engine, I got more speed than whatever you found online :)

BUT... big or small, it's all close enough as makes no difference for this purpose.
 
You must log in or register to reply here.

Forum statistics

Threads
113,190
Messages
1,428,252
Members
61,100
Latest member
Raneyd85
Back
Top