[103Control]

Hello,
Just thought I'ld ask for some direction here on the 1977 55 hp Evinrude on my sons 14' McKee craft. I had put a new 17" pitch prop on it when it first hit the water a few weeks ago and it rauns good up to 33 mph at 3/4 WOT but try and push it to wide open and it boggs down and you have to pull the throttle back to where you were. So I put the 15" pitch prop back on it that came with it and the same thing happens, only the speedo was reading about 27-28 MPH at the same RPMs.
Now the RPMs could be off since we are using the old Tach that was on the boat which used to have a Suziki 40. I was told here that it would work if I swithed it to 6 pole on the back of the Tach and some one else said that these old engines need a ten pole Tach ?
Any ways the Tach was reading 4300 RPMs although it sounded to me like it was cranking 5500 RPMs and trying to push more throttle would bog it down as if it was not getting enough gas to go any faster. I just replased the coils today and cleaned the plugs and fuel filter, checked fuel lines etc.
I'm going to throw it back in the bay at high tide and see what happens now but maybe some one here could tell me if the is a REV limiter or some timing adjustment I should try Etc. ?
Thanks Again, AL

[fireman57]

Sounds like a fuel delivery problem. When was the last time you cleaned and rebuilt the carbs. Might have some crud in a high speed jet. Make sure you soak them and blow them out good. While you are in there put a rebuild kit in them. Cheap ($20) and sure can't hurt.

[103Control]

Thanks for the tip fireman57, make sence to me.
I just bought a pair of good used carbs on ebay so I can rebuild these and let it run as is for now.
This motor was sitting pickled as he said for 13 years but the compression is at 150 x2 and it sounds pretty peppy up to the 4300 point so that makes sence. It seems at the point where the thottle plates would open wide is were it would choke, not enough gas.
I did adjust the throttle plates to open at the same time in harmony and now boy wonder says it is running better but the after the new coils, the tach stopped working?
I'll get the rebuild kits and try that next.
Alawys something,
Cheers,
AL

[papasage]

your carbs have to work with the timming . a link and sink will probabley help that . when you git a book it will show you how to do that . your timming nees to be set with carbs . it might be advancing to far or not far enough .

[fireman57]

Let us know what happens.

[103Control]

I'll look the timing thing up too papsage, I'll have to go over the whole thing if I can get the kid out of it a few days to put in the driveway.
I did get the big OMC book but that was kind of vague descriptions of a lot of OMCs.

I just got a service manual to really get me started to learn how to tune it the right way.

I'll post back when I rebuild the carbs and set the timing.

Much appreiciated,

AL

[Rancherlee]

your engine needs a tach with a 10 pole setting, big twin OMC's are 10 pole, 3cyl+ 12pole.