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351 pleasure craft

paul3

New member
"26 foot Shamrock with a 351 f

"26 foot Shamrock with a 351 fresh water cooled 1988, velvet drive, 700 hours. Replaced original carburetor with new do to gas leaking by. Engine starts and idles fine. Fuel filter has been changed, and new gas. Increase RPMs under way and engine loses power. I plan on changing spark plugs, wires, points and con- dancer and adjust timing. Anything else I should look for if this doesn't work, thanks"
 
In addition to what you plan o

In addition to what you plan on doing I would get rid of the points and install an electronic ignition kit they are cheep and well worth it. I would also change the impeller on the raw water pump. I had the same problem with my 23' correct craft fish with a 351 and finally found a small piece of silicone in the check valve at the gas tank. When I was in nutral I got plenty of rpm's but once I put a load on it it would loose rpm's and it would sputter and fart like crazy. I even changed the fuel pump. But it all came down to a restriction in the check valve. good luck!!!
 
"If Dons extra ideas don't

"If Dons extra ideas don't do the trick try replacing all the fuel lines and be sure to use marine grade. there could be a place ANYWHERE that colapses under pressure when your RPMs go up.... (because the lines are old) and the stuff you get at the auto parts store is too supple as well ;-) High Output electric fuel pump may help too.... and make sure the carb you put on is for a marine motor ... after putting on a Holly and and Eldebrock from the parts stores around here, we ended up with the original having to be rebuilt because it was the only marine one we could easily get our hands on! Hope you figure the prob out, and be sure to post when you do =) we are still having a prob with ours at 30 mph! ~Amy"
 
Make sure if you do the electr

Make sure if you do the electric fuel pump that it's adjustable and the highest output you can get ;-) speaking from experience! Amy
 
"Replaced the spark plugs, wir

"Replaced the spark plugs, wires, points, condenser, cap and rotor started boat up ran fine at all RPMs under a load. The plugs were covered with carbon deposits it seems that the old carburetor had a malfunctioning choke and the boat was running rich last year. Thanks all for your help, safe boating."
 
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