Just trying to get some thoughts on where to look....
If any of you have followed the Microboats forum, you know that I'm at the end of installing one of RMBuilder's cam combos. This has nothing to really do with the installation, just falls in the middle.
Back in April I got the boat fired up from being put away for the season. It fired up nicely on the hose and sounded pretty good. I decided I was going to retard the timing just a bit (older fuel precaution)... just a couple ticks via the eyeball from where the housing was gouged from the clamp (new MSD RTR distributor). I noticed that the engine's tone went south badly and put it right back. From then on, the throttle was sluggish. I thought that maybe old fuel was to blame and decided to go to the ramp.
At the ramp, got the boat started (took a bit) and had some hesistation/stalling. Took off and had a hard time getting on plane with two adults and my 4-year old. Boat was seriously digging a whole and took forever to plane but did. Attempting to run wide open would get you 4K RPM or so (engine was running to 52-5300 at the end of the summer).
As the trip went on the boat just started to feel less and less powerful. Finally, we got back to the ramp and she just refused to really cooperate (though we were able to get it up on the trailer under power). Got her home, flushed and put away. Figured that the problems might have been related to timing or bad fuel.
After all this, my cam came in along with my single plane Team G intake, etc. I tore everything down to do the cam install, found that my cam button/cover were messed up (but the cam was not walking... got it just in time really). Installed the new cam, replaced the cam drive, and buttoned everything back up. Went to start her up and ended up with a dead miss. Tried a couple of methods to locate the problem and really couldn't. Ended up replacing the plugs with new and also threw on my other wires (I couldn't get a good resistance test on the Mallory wires and I had a set of MSD wires already made). Fired her up on the hose and she came right to life. Throttle response was a little hesitant off idle, but it had always been that way when cold so no biggie. Cleaned everything up, put the flame arrestor back on, changed the fuel/water separator, and got her ready to go.
At the dock, the engine ran like absolute crap. I mean bad! It would not idle and would surge like crazy. Almost like a vacuum leak (there wasn't one). I finally got her to idle some and we left. Performance was less than stellar. Worse than the April trip. I went down from the 23P prop that was on the boat before to a 21P just so we could be easy on the new set up. The boat would barely get on plane. BARELY! And again, same load, two adults one small child. I only ran it for a short amount of time... just enough to get to a little beach so that we could hang out and my son could play. The trip back was pretty much the same.
So, I have three things that I can think of that might be causing this issue:
1. Poor fuel or water in the fuel. That would actually make sense with the whole hard starting/surging thing at the dock. If water was suspended in the fuel during pumping/pressure, then it would have had time to settle at the bottom (right at jet level) and cause all sorts of trouble.
2. Dirty/gummed up carb. I don't know what Ethanol (E10) does sitting in a carb for five months, but I bet it isn't good. I took off the carb last night and really didn't find anything... just some grit in the bottom of the carb. I cleaned everything and I'll reassemble tonight.
3. Bad coil. This is an observation based on just trying to figure out what the heck is going on. The fact that the plugs needed to be replaced though they didn't look it... I was surprised that replacing them actually worked. Just seems odd. Maybe the coil is too weak to fire a season-old spark plug? The old plugs came out, pre-cam change, looking like they're supposes to... tan and clean. I have another coil to try so that isn't a big deal.
The engine is a 385 small block Chevy... Eagle/SRP Competition Series bottom end, very stout and built by Jeff Riddle out of Chesapeake VA, Trick Flow heads, Felpro marine gaskets, etc.
Anyone have any thoughts one way or another?
Thanks,
Tom
If any of you have followed the Microboats forum, you know that I'm at the end of installing one of RMBuilder's cam combos. This has nothing to really do with the installation, just falls in the middle.
Back in April I got the boat fired up from being put away for the season. It fired up nicely on the hose and sounded pretty good. I decided I was going to retard the timing just a bit (older fuel precaution)... just a couple ticks via the eyeball from where the housing was gouged from the clamp (new MSD RTR distributor). I noticed that the engine's tone went south badly and put it right back. From then on, the throttle was sluggish. I thought that maybe old fuel was to blame and decided to go to the ramp.
At the ramp, got the boat started (took a bit) and had some hesistation/stalling. Took off and had a hard time getting on plane with two adults and my 4-year old. Boat was seriously digging a whole and took forever to plane but did. Attempting to run wide open would get you 4K RPM or so (engine was running to 52-5300 at the end of the summer).
As the trip went on the boat just started to feel less and less powerful. Finally, we got back to the ramp and she just refused to really cooperate (though we were able to get it up on the trailer under power). Got her home, flushed and put away. Figured that the problems might have been related to timing or bad fuel.
After all this, my cam came in along with my single plane Team G intake, etc. I tore everything down to do the cam install, found that my cam button/cover were messed up (but the cam was not walking... got it just in time really). Installed the new cam, replaced the cam drive, and buttoned everything back up. Went to start her up and ended up with a dead miss. Tried a couple of methods to locate the problem and really couldn't. Ended up replacing the plugs with new and also threw on my other wires (I couldn't get a good resistance test on the Mallory wires and I had a set of MSD wires already made). Fired her up on the hose and she came right to life. Throttle response was a little hesitant off idle, but it had always been that way when cold so no biggie. Cleaned everything up, put the flame arrestor back on, changed the fuel/water separator, and got her ready to go.
At the dock, the engine ran like absolute crap. I mean bad! It would not idle and would surge like crazy. Almost like a vacuum leak (there wasn't one). I finally got her to idle some and we left. Performance was less than stellar. Worse than the April trip. I went down from the 23P prop that was on the boat before to a 21P just so we could be easy on the new set up. The boat would barely get on plane. BARELY! And again, same load, two adults one small child. I only ran it for a short amount of time... just enough to get to a little beach so that we could hang out and my son could play. The trip back was pretty much the same.
So, I have three things that I can think of that might be causing this issue:
1. Poor fuel or water in the fuel. That would actually make sense with the whole hard starting/surging thing at the dock. If water was suspended in the fuel during pumping/pressure, then it would have had time to settle at the bottom (right at jet level) and cause all sorts of trouble.
2. Dirty/gummed up carb. I don't know what Ethanol (E10) does sitting in a carb for five months, but I bet it isn't good. I took off the carb last night and really didn't find anything... just some grit in the bottom of the carb. I cleaned everything and I'll reassemble tonight.
3. Bad coil. This is an observation based on just trying to figure out what the heck is going on. The fact that the plugs needed to be replaced though they didn't look it... I was surprised that replacing them actually worked. Just seems odd. Maybe the coil is too weak to fire a season-old spark plug? The old plugs came out, pre-cam change, looking like they're supposes to... tan and clean. I have another coil to try so that isn't a big deal.
The engine is a 385 small block Chevy... Eagle/SRP Competition Series bottom end, very stout and built by Jeff Riddle out of Chesapeake VA, Trick Flow heads, Felpro marine gaskets, etc.
Anyone have any thoughts one way or another?
Thanks,
Tom
