Operating at 4200ft..could I be running too RICH?

[MattP51]

J 150 2stk o/b 1990 v6 going through 6 gals in an hour operating at 1/2 to 3/4 throttle.......If this engine originally was calibrated for sea level, could I be overly rich?

The boat is only a 16' tri hull.

 

[guywithboat]

Re: Operating at 4200ft..could I be running too RICH?

It is possible with the thinner air. I would contact the manufacturer.

 

[MattP51]

Re: Operating at 4200ft..could I be running too RICH?

Good idea. Anyone know if leaning the carbs is as easy as turning a screw or are we talking re jetting?

 

[wilde1j]

Re: Operating at 4200ft..could I be running too RICH?

No question at all if your motor has sea level jets. No srcrews, just jet change. If your not sure about what to do either get an OEM shop manual, or have a dealer do the change.

 

[h_lankford]

Re: Operating at 4200ft..could I be running too RICH?


Are your spark plugs telling you that your are rich? My 16 ft with 60 hp at 3/4 throttle burns 4 ga/hr with just driver, so your 150 hp burning 6 ga/hr doesn't sound so bad. At 1/2 throttle you may be plowing and actually need to speed up for best economy.

Here is a purely mathematical way to look at it ( not proven by me on the lake) : Atmospheric pressure at sea level is 760 mmHg, at 4200 it is 656 or a reduction of 14%. So if you have sea level jets and running 14 % too rich, and then change to leaner jets, then you may theoretically save 6 ga/hr X 14% = 0.84 ga/hr. Your actual saving will likely be less than this as the 14 % doesn't apply to the whole 6 ga figure ( there is a certain minimum consumption no matter what).

 

[Texasmark]

Re: Operating at 4200ft..could I be running too RICH?

Man, sorry I can't help you. I am a sea level guy.

Mark

 

[Texasmark]

Re: Operating at 4200ft..could I be running too RICH?

Mr. Lankford. I don't know you, but I already like you. You deal in facts and facts are what make things happen. I try to answer the post inquiries with facts if I don't have true life event encounters (experiences) to supoport my jabbering.

Welcome aboard dude, er ah sir. 8)

Mark

 

[MattP51]

Re: Operating at 4200ft..could I be running too RICH?

An average car can drive an hour and use only 2 gals.....why do these small boat engines use so much gas?

 

[VADER8674]

Re: Operating at 4200ft..could I be running too RICH?

no transmision t aid with take off one gear thats go

 

[h_lankford]

Re: Operating at 4200ft..could I be running too RICH?

Mark, thanks for the welcome.

MAttP51 why do boats get poor mileage? they are plowing through water, not rolling on smooth asphalt for one thing. ANd boats propellers are churning and wasting energy, not directly putting it to use without slippage. Kinda like a P51 in the air. You like Mustangs?

Had fun with my 60 hp this weekend. Only minor glitches ( at sea level)

Harvey

 

[MattP51]

Re: Operating at 4200ft..could I be running too RICH?

I have a 68 fastback big block and a aviation nut