SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: 76 Southwind on August 08, 2008, 11:33:32 PM
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:banghead: I've got a fresh (cam break-in plus maybe 4 hours) 460 bored .30 over keith black forged pistons, weiand tunnelram, dual holley 850's, roller rockers, cam (specs @ home,I'm at the boat show in Tahoe now), problem is the motor fires up idles and runs great on the trailer, but put the boat in water and 3,500 rpm and the motor runs like crap poppin and spittin, etc. With my previous motor I got mid 80's- 429 Cobra Jet @ 5,500rpm. I'm thinkin' of taking my buddy's advice and take my boat to a reputable shop in Havasu, but that's a helluva drive to the shop. Is it possible for this motor to run good on the trailer if two push rods had bent and weren't working properly, cause that happened when the motor was brand new. Any help would be great, even if it's just to recommend a mechanic near say Elsinore or another body of water where we can take it out and figure this out. Thanks-Steve
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What compression and what octane fuel are you running , and what is the timing???
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Did you ever determine the cause of the two bent push rods?
What ignition system are you running?
Have you checked for vacuum leaks?
On the trailer with no load you will get a totally different response than you will under load.
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if you need some body to look at it, i would call jim brock at cyclone speed and marine he is in pacoima i think that is close to you.
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if you need some body to look at it, i would call jim brock at cyclone speed and marine he is in pacoima i think that is close to you.
x2
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Did you pull the plugs to see if you can find a or the bad cylinder s?
Check compression from there. Maybe a bad plug or wire. That would be wishing for the best.
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:banghead: I've got a fresh (cam break-in plus maybe 4 hours) 460 bored .30 over keith black forged pistons, weiand tunnelram, dual holley 850's, roller rockers, cam (specs @ home,I'm at the boat show in Tahoe now), problem is the motor fires up idles and runs great on the trailer, but put the boat in water and 3,500 rpm and the motor runs like crap poppin and spittin, etc. With my previous motor I got mid 80's- 429 Cobra Jet @ 5,500rpm. I'm thinkin' of taking my buddy's advice and take my boat to a reputable shop in Havasu, but that's a helluva drive to the shop. Is it possible for this motor to run good on the trailer if two push rods had bent and weren't working properly, cause that happened when the motor was brand new. Any help would be great, even if it's just to recommend a mechanic near say Elsinore or another body of water where we can take it out and figure this out. Thanks-Steve
Sometimes carburetor and ignition system gremlins have damn-near identical symptoms. Therefore if you are not sure whee the problem is, then it's always best to first diagnose/repair the ignition system and affirm that it is working perfectly. Only after you are certain that your ignition is fine should you diagnose carburetor symptoms. (Imagine trying to figure out what seems to be a flat spot or upper rpm miss by playing with your carbs when the culprit is actually a bad condensor in your distributor!) If you don't have the proper equipment and experience for diagnosis, then I suppose you can take a few stabs in the dark but remember there is nothing wrong with taking it to an experienced reputable mechanic or service facility.
LO
p.s.: +3 on Jim Brock if he's near you and has the time.
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Thanks for all the help, I'm going to give Mr. Brock a call and go from there. I really appreciate all the responses. Thanks Again Guys! I'll keep ya posted on how things go now that I've got somewhere to go.
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I think Brad can tell you how to take care of that problem. He had the same thing happen to him!
Sorry Brad! ;D