SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: Duke on August 18, 2011, 06:52:56 PM
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your thoughts please :o
vacuum pressure blah (http://www.youtube.com/watch?v=HftkPUEMg9I#)
at idle, then i pulled on the throttle cable a little bringing the rpms up,
this is with the air bleeds (i think) on the metering plates turned out about 4-5 turns, thats where i get the highest amount of vacuum pressure. its bounching around between 16 - 18, revved up it goes to about 18-20
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motor has some use on it but not terible, i have seen worse. maybe a toon up but ... does it run bad??? are you having a prob???
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its been sitting for 5 years, and iv been trying to get it running, i rebuilt the carb myself, iv also changed out the points, condenser, rotor, cap, ignition coil, ballast resistor, all the wires, idle timing is at 18* and total is at 32* changed out the alternator, which is feeding the system 14.5volts at idle and increases with the rpms, had the starter rebuilt twice and is cranking over really well now, last year i swapped out the mechanical fuel pump for an electric one (5-7 psi), put spark plugs and spark plug wires. and now im trying to tune it so i could get a day at the lake out of it. basically trying to get the right air/fuel ratio
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Sitting for so long with your springs putting pressure on your cam lobes may have flattened out the cam. Your valves aren't opening at the same time which is giving you jumpy vacuum pressure, could also be caused by a valve not seating all the way. option A, option B is going to be a vacuum leak. You said you already rebuilt the carb so I ruled that out. Just an opinion. O0
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Sitting for so long with your springs putting pressure on your cam lobes may have flattened out the cam. Your valves aren't opening at the same time which is giving you jumpy vacuum pressure, could also be caused by a valve not seating all the way. option A, option B is going to be a vacuum leak. You said you already rebuilt the carb so I ruled that out. Just an opinion. O0
sounds like a valve adjustment is in order.
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ok how does it run??? cant tell by the sound??? that vacuum gauge needle to oppion is not moving that much. if its running on all 8 and its running good leave it alone. go have a good day.
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i dont think it was really that bad :-\ i do feel that your air bleeds are adjustad way to far out and hiding a different problem. I always start at the factory settings and go from there, my bleeds are 1to 1.5 out.
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i dont think it was really that bad :-\ i do feel that your air bleeds are adjustad way to far out and hiding a different problem. I always start at the factory settings and go from there, my bleeds are 1to 1.5 out.
it doesnt want to run if the bleeds are turned less than two full turns out. at which the vacuum pressure is closer to about... 14-15hg
i think holley said to turn the bleeds out 'till i have the most amount of pressure.
i agree, i was scared the bleeds were gonna fall out they were turned out so far!
its running like crap right now in my opinion
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ok. any lifter noise???? is it missing or not running on all 8???
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not sure about the lifter noise. yes its running on all 8 cylinders, my number 4 spark plug has a bunch of detonation on it already so im thinking i need to change the spark plugs again. otherwise the spark plugs look a tan color, some of them have a little bit of black collecting on them.
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ok first the spark plugs!!!! the ones that have black on that. is it oil or soot????? big difference.secondneed to know about lifter noise. when it was running did it have a tick noise or was it more of just a rumble????
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i dont think it was really that bad :-\ i do feel that your air bleeds are adjustad way to far out and hiding a different problem. I always start at the factory settings and go from there, my bleeds are 1to 1.5 out.
Kinda where I was at. Generally, 1/2 turn to 1.5 turns out is all you need on the air bleeds. Hows the float level? How big a carb? what size engine? Hows the fuel pressure at speed? Almost seems like way too small a carb for the engine maybe?
The lifter noise you're describing could be detonation. Lots going on there and need more info. , but with THAT much vacuum, vacuum advance dizzy maybe causing issues? severe timing issues? Could really be anything at this point.
If one is detonating regularly, so are/have the rest, just not ID'd yet, or the valves/pushrods are all bent, holes in pistons, etc, IMO.
Ray
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im leaning tword carb or timing, if there was a hole in a piston that needle would be bouncing really bad!!!!
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Kinda where I was at. Generally, 1/2 turn to 1.5 turns out is all you need on the air bleeds. Hows the float level? How big a carb? what size engine? Hows the fuel pressure at speed? Almost seems like way too small a carb for the engine maybe?
The lifter noise you're describing could be detonation. Lots going on there and need more info. , but with THAT much vacuum, vacuum advance dizzy maybe causing issues? severe timing issues? Could really be anything at this point.
If one is detonating regularly, so are/have the rest, just not ID'd yet, or the valves/pushrods are all bent, holes in pistons, etc, IMO.
Ray
after the video was shot i took out the spark plugs, my number 6 spark plug wire wasnt completly on the spark plug, the metel clip inside the boot was bent and had white around it. (im going to run it again tomorrow and see what its like, i'll post a video for everyones entertainment)
ok im going to bring the air bleeds back down and see what happens. float levels seem fine, they're just below the sight and if i rock the boat a tiny bit of fuel will spill out. (running or not) dont have a fuel pressure guage, the measurements i gave earlier are just what the fuel pump is supposed to produce. 5-7psi. carb is a 750cfm vac sec, engine is a 454, unsure if theres anything done to make it bigger but i REALLy doubt it, as the heads are small oval's, and the bumbstick is an RV cam. dizzy is a mechanical advance. im going to have to double check the timing, maybe the new ignition coil and larger spark threw the timing off. (gotta borrow a timing light again)
the sound it makes is more of a rumble, and the black on the spark plugs..... i'll take some pictures tomorrow but its more on the soot side, and i want to say like theres a tiny bit of fuel still on them. wow im having an idea, that must mean its running rich.
thanks again everyone!!!
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i hope your pump is not connected to the engine during all this testing
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The needle on your vacuum gage looks like it is made out of rubber. I'm guessing it looks that way because of your video cameras low resolution.
When on the water, I take an angle gage on a flat surface to give me a reference point for tuning out of the water.
See how much the angle changes while the boat is stationary and when you are on plane.
With this information you can raise or lower the trailer tongue to achieve the same angle when out of the water.
I hope this all makes sense.
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not sure about the lifter noise. yes its running on all 8 cylinders, my number 4 spark plug has a bunch of detonation on it already so im thinking i need to change the spark plugs again. otherwise the spark plugs look a tan color, some of them have a little bit of black collecting on them.
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If it looks like peper, it's your piston
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took it over to jim at cyclone, apperently my spark plugs were gapped wrong (i gapped them the way the box told me too) and i need to get plugs that run a bit hotter, my primary point gap was off, and the timing was down to about 29, he regapped everything, raised my timing to 35-36, and adjusted the air bleeds, sounds and runs MUCH better. gonna hit the lake soon hopefully everything works out
thanks to everyone that helped out i appreciate it!!