View Full Version : 30 4 cylinder lacks power
05-05-2004, 10:12 AM
" I have two 3.0 4 bangers in my chris craft 25. One will run up to 4200 rpm and the other only 3000 rpm. I Checked timing and corect firing order on both engines to be to spec "6 btdc" "1432 order". Checked each clyinder compresion. The good engine clyinders range 100-145 psi, the lacking engine is all 150 psi on all four. Electronic ign on both engines, good sparks. Both idle well. Both run the same temp. These are raw water cooled, running in saltwater.
Both throttle plates open all the way, chokes off at temp. Same gas. All new fuel filters and pumps.
Any Ideas?, I will try swapping the carbs tommorow and see if the problem goes to the good engine "
05-05-2004, 11:34 AM
Have the props been changed lately ~ Any chance of a mismached set & you are beening prop governed on low RPM engine?
05-06-2004, 11:47 PM
" props are the same, 12X10s Swaped carbs and the problem is still there. I think the exhaust hose or muffler is restricted. There is a lot of cooling water in with that exhaust at crusing speed. If you look at the exhust comming out of the transom its like a sold stream of water 2 1/2 inches in diameter. "
05-08-2004, 12:06 PM
Another thought. Have you checked the timing advance when at speed? You didn`t mention what Ign.system is installed But have seen advance curve modules crater & cause all sorts of wierd problems
Back pressure is a good thought also
11-25-2005, 11:14 AM
"I had 2x 360 HP gasoline engines, one was left, and other was right turn, connected to the Borg Wagner hidraulic gear box. I've replaced engines with the two turbo diesel 270 hp that turns in same direction, can i keep my old borg wagner and just ad a gear to reverse turn direction?"
11-25-2005, 11:43 AM
"It depends on what model gears you have. The 5000 series gears are bi-directional and will work with no modifications, some of the older gears can have the pump direction changed. It's a simple process and is explained in the B/W service manual. Some of the gears are not going to work at all. I would find out what model you have, then get a hold of the proper service manual and read through it.
P.S. In the future you should start a new string for a new topic or question. It will yield more results as many readers pay no attention to replies that appear under very old posts."
03-06-2006, 08:08 PM
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03-06-2006, 08:09 PM
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