Russell Bear
Well-Known Member
- Joined
- Aug 31, 2002
- Messages
- 1,703
Here's what I have. Scratch built scale wood hydro that weighs 15.2 lbs. 2005 MAC 67 (Big bore carb) with head clearance of .008” with the AB black pipe @ 11 1/2". Running 45/18 Byron's fuel and a Mark Sholund X460/2. The engine has close to a gallon through it so it's fairly new.
What we are seeing is that the engine doesn't like to rev all that much when on the table or underway. When starting the easiest way to get it started is to pinch the fuel line, and when it does run it is sloppy rich. Have to keep the engine at least half throttle or better to keep it running. When on the water it will run pretty good for a couple laps and then starts to fall off the pipe in the corners and then wakes up again until the next corner. It’s hard to keep on the pipe. We tried a number of different props. The ones that did get up on plane did the same thing.
After the run we looked at the plug. Some plugs were slightly pulled and in better shape than others, but there were a few that were burnt black and the coil was pitted badly. I can only get one or two runs on a plug.
I am attaching a couple pictures of the head button and the top of the piston. I am seeing quite a bit of pitting on both, but the bowl looks good, just pitting around the perimeter of the button.
So anyone out there know what I should try to get this MAC running?
What we are seeing is that the engine doesn't like to rev all that much when on the table or underway. When starting the easiest way to get it started is to pinch the fuel line, and when it does run it is sloppy rich. Have to keep the engine at least half throttle or better to keep it running. When on the water it will run pretty good for a couple laps and then starts to fall off the pipe in the corners and then wakes up again until the next corner. It’s hard to keep on the pipe. We tried a number of different props. The ones that did get up on plane did the same thing.
After the run we looked at the plug. Some plugs were slightly pulled and in better shape than others, but there were a few that were burnt black and the coil was pitted badly. I can only get one or two runs on a plug.
I am attaching a couple pictures of the head button and the top of the piston. I am seeing quite a bit of pitting on both, but the bowl looks good, just pitting around the perimeter of the button.
So anyone out there know what I should try to get this MAC running?