The “DRAMA” continues! I just had a ton of money put towards upgrades on my boat, (Hydraulic steering rams Powerflows, new tips, oil cooler, all new throttle and shift linkage, out drive serviced, coupler, u-joints, and assorted miscellaneous items, hoses etc.). After paying a hefty bill, I took it to Havasu. First day, the MSD coil shorted out, the impeller came apart, and last the starter broke off. Back it went into the shop! Next trip out, (Test and Tune), three minutes in the water, the primary bowl float sticks, no problem, I carry enough parts to rebuild most holleys, minutes later the secondary does the same. I cruise around the lake and notice a bad vibration coming from the rear of the motor, ( 468 cu in.). The vibration gets so bad the hose from the water pump wiggles it’s way off flooding the engine compartment, resulting in shorting out the MSD box. I took it home removed the out drive along with the drive shaft. Ran the motor alone and the wicked vibration is still there. So my question is, what next? Buy a new coupler, flywheel or pressure plate, new motor, where does it end. I’m far from rich and can’t buy high dollar parts just for testing purposes. I’m embarrassed to say, I’m into the repairs almost 20 grand on a 16 thousand dollar boat. Any ideas what I should check next? Can the pressure plate go out of balance, can the coupler be factory defective? Flat cam, cracked crank, someone tell me it’s a vacuum leak or something stupid. Anyone?
It sounds like one or two cylinders are not fireing. Do an "engine balance" test. Set a high idle (2000 RPM is fine) and pull and replace the wires on all the plugs in turn. The idle should drop by the same ammount on all plugs. You may find one or two plugs don't drop at all. That means no fire in those cylinders.
Originally posted by BOFH:
It sounds like one or two cylinders are not fireing. Do an "engine balance" test. Set a high idle (2000 RPM is fine) and pull and replace the wires on all the plugs in turn. The idle should drop by the same ammount on all plugs. You may find one or two plugs don't drop at all. That means no fire in those cylinders.
I followed your test recomendation....no.4 and 8 plugs not firing correctly. Got a new MSD cap and rotor, somewhat of an improvement. pulled the plugs out, same cylinders show lean condition.
What crank shaft are you running???? If it is a 454 crank then they are externally balanced, unless you had it internelly balanced. I would check to see if the weight is still on there if not then you need a new flywheel, or if you had the flywheel off recently make sure that you lined it up correctly...sometimes the dowel pin in not in the crank and you can get it out of phase. Good luck
Bernie
Please tell me that you replaced all the plug wires......
78Elim(Justin)
OK. If thje Balance Test show issues with 4 and 8, this is a good thing, in that we have a problem we can see. (Easier to chace those than ghosts!)
Lets start with the lean condition... What is your induction? (Carb or EFI) Also, (and this is a problem that stumped us for a month) get a dial gage and check the valve lift. (Also a compression test) We want to see what is different about those two cylinders. If the intake on those two flattened a little bit, it would give you less of a charge, and could lean it out a bit...
I changed the cap, rotor and wires, somewhat of an improvement on vibration. 4 and 8 are firing now. compression on "all" cylinders is 150 or better. As for your question it has a tunnel ram with 2 holleys.
Next I changed the intake gaskets and carb base gaskets, to eliminate possible vacumme leaks. put everything back together....still vibrates just as bad. Sprayed carb cleaner while running, looking for any other leaks.....nothing.
So the balance test now shows 4 and 8 to be fine? Hmmm... How about fuel pressure accross the carbs? Both getting the same ammount? Do both carbs show the same vacume readings? This one is a real reach, but if you can get ahold of a Flowscan Twinscan gage, see if both carbs are flowing the same ammount of fuel...
And keep the faith! It's getting better!
So, I pulled the motor today, coupler showed no damage, flex plate was 180 degrees off, the key has been grounded off so I assumed, for lack of a better reason, that it was put back in wrong. I clocked it to where it should be. Tomorrow I will finish complete instalation and fire it. I'm confident that will be the answer to my vibration problem. I will post the findings tomorrow.
All you guys that have contributed to the trouble shooting, to you I am greatful. Lets keep our fingers crossed.
Thanks again,
No Drama
Any update
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