SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: NORDIC454 on July 12, 2010, 05:31:13 PM
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ok, so before the motor went bye-bye, i was running a 650,or 700 vacuum secondary Holly. jetted @ 68/70. carb wise, it ran good, fired immediately, no throttle. setup with a chevy hi-perf aluminum intake. now with the new motor, i have a Weiand team G single plane, with Nordie's 850 that was setup on his old 460 with the tunnel ram. it runs great, rich but great. no stumbbling, clean all the way through the RPM range. my problem is that it wont start for shit. have to floor it while cranking it untill it fires. usually 5-10 seconds. it was jetted @ 80 all around. i brought it down to 78/76, not running as rich, no more smoke when it starts, but the hard starting is the same. i am running MSD7AL ignition with pro-billet dizzy. delco plugs gapped @ around .045. any thoughts? is itstill way to big in the jets? pease help
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also, what should my fuel pressure reg. be set at for this app? thanks
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try .035 on the plugs and your original jet size
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it sounds to me like you are either boiling the fuel in the bowl causing it to overflow out the vent tube and into the carb, or your float level is too high causing flooding. just somthing to check
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try .035 on the plugs and your original jet size
terry, he is running an msd witch takes a wider gap on the plugs. no?
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I dunno Ralph, do they? I run .0180- .020 to get the mag to start. Used to run small gaps on bikes to get em to start. Thot it was worth a try. Baybe lean it out or close throttle blades so they're on the transfer slots. Close primaries by opening secondaries.
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What would be original jet sizes? The size on the 700? I don't know what was original on the 850 I'm messin with now
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Depending on the List # it could have been either 80/80 or 80/78
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NORDIC 454
More information is needed about your setup if you don't mind....
Your fuel pressure should be somewhere in the neighborhood of 6-7 psi......
You say you have to open the throttle to get it to start, is this every time? or just cold....If every time, it sounds like a couple of problems are possible...Next time it's running and you shut her down, pop back there to see if the squirters are dribbling fuel....There may be a problem in the accelerator pump circuit..
Also, does it idle clean when it starts, or does it need cleaned out by clearing it with a few revs?, I have seen blown power valves do what you describe, they normally refire and need to be "cleared" before they will idle....It could be the idle has been adjusted with a bad Power valve and you never knew it was bad...pick up a 4.5 and maybe a 6.5 to throw in the toolbox and experiment.....
I have also seen the wrong metering plate gasket hand out an ass or two.. :thumbdown:
Good luck, no guarantee it will be carburetion, but I think you are on the right track... ;)
What would be original jet sizes? The size on the 700? I don't know what was original on the 850 I'm messin with now
Gimme the list number off the carb, I have the OEM info for virtually every carb ever built since the early '50's
GT
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I dunno Ralph, do they? I run .0180- .020 to get the mag to start. Used to run small gaps on bikes to get em to start. Thot it was worth a try. Baybe lean it out or close throttle blades so they're on the transfer slots. Close primaries by opening secondaries.
Pretty common on a mag ignition system with a gear reduced starter, they don't turn fast enough for a good spark, do you have a separate ignition switch to get the motor turning good before adding fire? Sorry for the jack....
BTW I like .040" to start with as far as gap on a naturally aspirated dealio... :sly:
GT
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Pretty common on a mag ignition system with a gear reduced starter, they don't turn fast enough for a good spark, do you have a separate ignition switch to get the motor turning good before adding fire? Sorry for the jack....
BTW I like .040" to start with as far as gap on a naturally aspirated dealio... :sly:
GT
short jack:
Yea, gotta have a ground switch, only way to shut it off. MSD says it wants around 240 RPMs to fire. Batt was pow last week and I told ray to just pull me out in the lake and I'll just float. So jay askes this dude if he had a jump box and He flips my an Optima and a set of cables and goes, " just get 'em back to me later heres my number"!
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it only happens when its been ran and warm, and it idles, but is a little rough for a second or two. when its cold it starts nice. i would love to get this figured out by this weekend. the list number on the carb is 4780 0954
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it only happens when its been ran and warm, and it idles, but is a little rough for a second or two. when its cold it starts nice. i would love to get this figured out by this weekend. the list number on the carb is 4780 0954
Take a peek down it's throat after shut down....Text book fuel overflow... ;)
GT
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there is no fuel dripping when i shut it down. but i only fired it for a minute. right now its firing up immediately like it used to do at all times. but as soon as i run the boat and it get warm , it is hard to start
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there is no fuel dripping when i shut it down. but i only fired it for a minute. right now its firing up immediately like it used to do at all times. but as soon as i run the boat and it get warm , it is hard to start
Does the fuel line run anywhere near a heat source?
GT
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here is from the pump to the carb. from the tanks into a T, down the passanger side bildge to the pump
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So just a little update. Got the starting issue figured out. Pilot error, my dumb ass was flooding it by pumping the go pedal. Now it fires up beautifly the first time, every time. Still running too rich, I can smell fuel every time I shut it down,(no leaks),but running strong
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Be sure the floats are adjusted it is critical on Holleys. If you smell rich or it burns youe eyes when running its rich. Check timing advance to burn off excessive fuel, and plug gap,etc Also be sure the air bleeds are clear, spray with wd 40 every so often.