SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: sandeggo on June 14, 2010, 09:38:19 AM
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ok so the second trip with my tunnel ram is done.
the carbs are pretty dialed, idles clean and fires right up. no bogs off the line, not a single backfire.
Mmorial i put new plugs in and it fired right up and ran great all over. sounded more throaty and cammy.
plugs are autolites (all they had in parker), gapped at .045.
on Memorial when I'd stab it while cruising, it would bog a little and then if i stayed in it, it would clean up, burn it, and GO!
now when i was running saturday, starting got a little harder (had to use the gas pedal) and when i try to run full pedal, it bogs and loses about 400 rpm. never cleans it up.
I didn't pull a plug but i guarantee at least one is fouled. it just doesn't have the same power that it initially had. up to 3/4 pedal is great. I was thinking about changing the cams on the carbs and opening the gaps a little more. what are your opinions.
the carbs have 6.5 power valves, but i cant remember the jet sizes. i want to say 76?
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I will be watching to see what the others say. Initially I was going to say you probably need more lik a 4.5 pv.....but that wouldn't explain why it ran ok at first with those(6.5's) in it.
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It's as if the initial hit of the secondaries is too much fuel
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the cams on the secondaries, put the screws in the number 2 holes! the fuel will come on a little later, and the butterflies will be a little more open...they recommend this with higher idling engines anyway!
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that makes total sense, considering i'm idling around 11-1200 rpm.
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What ign are you running? I would look at the plugs to be sure one isn't closed up. Again depending on ign to satisfy bigger plug gap .045 should be ok.
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pertronix with msd coil. decided not to hook up the box.
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Th box is what produces the increased spark needed to fire large gaps
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i just thought of something that may or may not be related to this issue
the first time out with the setup boat ran great, gas was purchased at chevron 91 octane
the last 2 times, its had this problem and gas was purchased at parker oil. 91 octane
like i said i dont know if it is related but ill try chevron next weekend and see if it helps.
i put the pump cams in the #2 position and dont notice a difference at all.
I also got all new plugs and opened the gaps to .045'' and dont notice a difference either.
when i pulled the plugs, the 2 inside ones were wet on both heads, the outside ones were dryer, but had been wet at one point.
this was just removing the plugs after the boat set for 4 days, not running it and pulling the plug
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Sandeggo,
You are way over jetted....Step it down a couple numbers and try it again...76's are a lot of fuel for that mouse IMO.
Try some 74's and get more info. The accelerator pumps only work while the throttle blades are being moved.
The best tuning aid in the world is a good vacuum gauge and a working tach.
Also gap the plugs at .042" until you get the fuel issue straightened out.
Good luck, boat came out bitchen BTW :thumbup:
GT
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should i try to hook up the vacuum?