How much fuel..?

[Ted Stryker]

I have a heavily cut 200 Merc will all 260 injection and electronics, The engine is through with a new break-in and ready to be turned up... My dilemma is that at 6,000 rpm My egt's begin to climb toward 1200 so I back off... My fuel is set on 101 with an a48 box, and I though sure that it would be enough.. I have a Bosch pump with the 39 lbs regulator and low hour injectors... For what it's worth, the egt's are pretty equal in temp...

[Jay Smith]

Your compression is what ? Timing is at 25* ( total ) And I assume your at sea level ? Make sure your not reading flame instead of EGT. If an ECU is too rich a pyrp will read the unburned fuel going down the exhaust and give you a false lean signal. I read piston crowns the ONLY way NOT to be fooled about jetting IMO.... 101 with an A-48 should be REAL rich at sea level with 140 compression with 25 degrees total timing.

Good luck,
Jay

[patchesII]

i'll answer for kevin since i know the motor well.thanks jay, this is a motor that you cut for me in 2003 before i sold everything to my brother. you cut the motor to as closely resemble a drag as possible. elevation is 200ft, timing is 25*, comp is 130,15 inch drag mid. break-in started with the fuel at 105 with relatively high egt's and i assumed they were flame fronts. we were kinda thinking we could get away from the flames at 101 but i guess not. i know its kinda hard to say since you aren't looking at this motor but do similar motors usually end up with their fuel around 99. i know he really wants to play safe and not burn this thing down. is a high rpm throttle chop the only way to check plugs. i know his boat would take alot of water in the boat and on top of the cowl(drag cowl with louvers on top) if he just killed it. thanks jay for the help, erik kiser

[Jay Smith]

Eric,
You could as quick and as safe as possib;e shut down and read #5 at BDC . Look at the intake side of the crown and look for a dampness about the width of a dime from the intake ports outward toward crown center this is jetting dead on correct. A distant of a quarter a little too rich and chaulky dry of coarse too lean most of the time if a piston is building carbon its jetted either safe of a little rich. 130 lbs cranking compression at sea level with 25* timing is super safe at pump gas super unleaded , I'm not versed in your A-48 chip it being a "pirate" or OEM vintage BUT if its OEM it should be fine at a "high" 97 or "low" 99 with your low compression and muggy air in La... BUT I would read the plugs to make sure and be safe..

Good luck,
Jay

[Ted Stryker]

I'm back... I plan on upping the compression and using mixed fuel to at least 175 lbs. at times due to the nature of the port work but for lake riding I will cut My 130 lbs. heads to about 140-145 lbs. and use premium pump... I reckon I will start pulling the heads again, I was doing it about every 1 hour of run time during break in but slacked off to not fatigue the threads in the block.. Every time the pistons were rich and wet, I haven't checked them after the fuel setting was dropped to 101... Thanks again, Jay...