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Questions carb or prop size

A

Anonymous

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Questions carb or propeller size
13 ft cottonmouth with poly 3 seater.
Motor small block Chevy 400 30 over 202 fuelies 1.5 roller rocker. 10 to 1 compression cam rpm1800 to 4800
Sorry don’t remember the specs
Builder est. 350 to 375 horse.

The prop is a 72 34 paddle.

What size carb do you think this motor should have.

Is this the right prop?

The reason I ask is it not producing the rpms. The motor feels to my like it wants more fuel. The motor has a 500 cfm carb. Its what was on the old 350? I think it needs a 600 to a 650
 
What rpms are you hitting with that prop and setup. I have a friend with a worn out 400 and a 300 2bbl swinging a 74x30 wideblade at 2800 rpm, with a good motor you should st least be able to hit that rpm or higher. I know some people that have had problems with the 2.02 heads on dd 350, seems the big valves killed the intake velocity on the smaller motors. One guy changed to 1.72in. 1.50 ex. heads and loved the performance gain. Waterthunder could probably help you in more detail, hes definatly the sb chevy guy around here, I have just toyed with them in the past.

Larry
 
had me a direct drive 400 out of a 72 wagon, bone stock with a 72x34 prop would push a 15x7 aig hull with polymere all over the hill at 2800 rpm
, your engine may be losing low end torque with the cam you have
 
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