2.5 efi 260 computer on big boats...
 

I know this is more of a Scream and Fly question, but I forgot my password over there, and there are plenty of high performance outboard guys here.

I have 260s on my 30' Spectre. My mechanic has lots of experience with these but not on big boats. I have the 56psi computers. He put the DDT (whatever that is) on them and they are set on 99 which he says is very rich. I like rich, because rich is safe and I break plenty of sh!t anyway. He says he thinks that it would be safe to change them to 95, and I would get better performance and less fouling of the plugs (which hasn't been much of a problem). On the otherhand, He didn't want to do it, because he wanted to get some input from people that have run 260s on bigger cats like this one.

The questions are :
1) Is he correct.
2) what the hell do these 99 and 95 numbers mean?

Thanks in advance...:cool:

how hard do you spin them. 95 is probably to lean. kept mine at 98 and went 8100 rpm

Are they stock 260's? Do you know what number box you are running, i.e. A-63, A-6, A-13? (These are some of the more common 56 lb. boxes.)

Anyway, if they are stock 260's, 99% is probably a little rich. Also, depends on your compression. However, I would NOT drop it down to 95 for everyday running. If they're completely stock, including compression (135 +/-) 97 is probably as low as I would go. Only because the 56 lb. boxes are for the champ and drag motors, you can get away with less percentage with stock 260's.

From the factory the 260's came with 39 lb. (gold) regulators and they set the boxes at 99 %. The 56lb regulators are black.

The numbers are a percentage and affect the entire fuel curve throughout the rpm ranges.

Another note on the 56lb. ECU's, most of them have a lean spot around 5000 rpms, so try to avoid cruising in that range. ;)

We think it is an older box (a17 or a13), but reprogramed with the a63 fuel curve.

Do you see any danger in lowering them to 97???

thx.

What Is Your Goal. Fouling Plugs While Ideling Around The Docks? You Can Cut The Purple Wire I Think That Makes It Run Rich At Idle. Check The Manual.

260 Settings
 

Question for you. Why does the size of the boat alter the tuning? The motors don't know what boat their on.

A Motor Knows When Its Laboring Too Hard