need a load to run smooth?

danthern

Petty Officer 1st Class
Joined
May 28, 2003
Messages
217
Hey guys....I need some expert advice. I have a 1977 24 ft.omc stern drive cruiser that was given to me by my father in law who said "it just needs a little cleaning up".Turns out it had a busted block because the water wasn't drained. To make a long story short, I've installed another rebuilt omc 351W 235 hp. I've yet to have it in the water. Right now, it idles beautifully at 600-700 rps and will take fuel up to about 1000 rpms where it begins to bog and miss terribly. new ignition componets,(cap, coil, plugs, wires, rotor button, points and condenser). Timing is set @ 4 btdc, point gap at .019. Carb was supposedly recently rebuilt(Holley 4 bbl. 4160 cfm), I've taken it apart basically, changed the power valve. The Holley guy said that if it was the accelerator pump, the motor would bog but then catch up, it does not do that, continues to stay very rough. Here is my big question....A mechanic friend told me that the boat needs to be in the water under a load in order for the timing to advance or something akin to that. The way that he explained it made sense, but I need another opinion or two....anyone got any thoughts??<br />Thanks,<br />Dan
 

blderman

Cadet
Joined
Jun 10, 2003
Messages
14
Re: need a load to run smooth?

Well I just bought a 92 blue water with a 4.3L and was trying to give it a tune up on land and was having the exact same problem as you. So I took it out on the river yesterday and in about 20 minutes I had it running beautifully. The exhaust needs the back pressure of the water in order for the engine to run correctly and I hadn't thought of that when I first started to try and tune it. Good Luck<br /><br />Jason
 

Juancho

Seaman
Joined
May 18, 2003
Messages
50
Re: need a load to run smooth?

bamaboater,<br /><br />I would definitely try to tune it up out on the water, however I am skeptical that will fix your problem. Sounds like either you accelerator pump/jet in your carbs are not working right, or your distributor is not advancing correctly. If I were you, I would start with the distributor, since you have already rebuilt your carb.
 

danthern

Petty Officer 1st Class
Joined
May 28, 2003
Messages
217
Re: need a load to run smooth?

Thanks guys....will be taking it on the water this weekend, weather permitting. I'll let you know what happens.<br />Thanks!<br />Dan
 

rogerwa

Commander
Joined
Nov 29, 2000
Messages
2,339
Re: need a load to run smooth?

How about restriction in the fuel supply.. Boats been sitting, maybe junk in the tank. Clogged pickup.. Fuel Pump New or existing? Inline filters or water separators checked?? Sucking air a leaky connection? Just a thought.
 

danthern

Petty Officer 1st Class
Joined
May 28, 2003
Messages
217
Re: need a load to run smooth?

Thanks for the ideas...I actually took the fuel line and put it into a bucket of new gas to rule out what you're talking about a few days ago. Took it out today, continued to skip and sputter after 2000 rpms. Gonna rebuild the carb(it has been sitting for a while since last rebuild) and see what happens then. The struggle continues...
 
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