Carb help pls
 

Have a 540 na motor with a 850 cfm carb. Motor has patriot perfect heads, 10/1 compression, custom rmbuilder cam, Vic jr intake, sm exhaust. Power is falling off at about 5200.

Here's the question: which dominator is going to work best ( least tuning) for my application? Also thoughts on using 4150manifold with dominator and adapter plate.

I'd think a 1050 would be a decent fit. Regardless, you're going to want to do some tuning with whichever model you buy.

Also, are you sure the cam has nothing to do with the power falling off?

Dito, What are the cam specs? Outdrive ratio, prop, boat weight, alot of varibles..

Hook a long piece of vac tubing with a vacuum gage and look at WOT vacuum. If it is not 0 vacuum you may need another carb. What do your plugs look like are you lean???

I would check for sufficient fuel flow, as in fuel pump, fuel line size, etc. Also, make sure your jetting is fat enough. If you are having to run really large jets, going to a smaller sized air bleed will help get you the fuel you need.

A 850 properly setup should be enough carb for you imo.

Are you sure your heads will support 540 cu/in?
Did you dyno? And are you sure you have enough power to turn the specific prop you have on the boat.

Fixx
 

NO OFFENCE,i gave you good advise before with the 496 and your boat rocked :)


As i said on donzi.net,,you need to up grade your fuel system first,the 3/8 fuel line wont be enough to feed a 850 let alone a 1050 dom..you will need to go from the tank's pick up back with a 1/2 '' line..Call teague marine and have them make you a 1/2'' pick up tube..is the anti siphen ball still intact?? that will restrict you ..

also if it is to rich it will be killed on the top end..a lot of people think it's the other way..only lean will cause this...NOT true...rich will hurt way more than you think..quick ck if everything else is good..drop 6-8 jets #'s and run..you will know quick...make sure you use a GPS as well and run the way it is before as well..Rob

Just curious, can't this be verified with fuel pressure or something before he tears out all his 3/8" line and spends the money for 1/2" line. I only ask because I know plenty of 540's using stock gas line with no problems. Not saying 1/2" isn't better.

Fixx
 

The gas tank is mounted in the front of the boat so the fuel pump has to suck the fuel a good 12-15 feet before it gets to the motor,,he already ran the boat with the carb he has on it now,when he removed the rear fuel bowl to up the jet size he noticed their were no jets in the metering block and his spark plugs were still white (lein).. All the guys with 540's over at donzi.net run a bigger fuel line,with all the porposeing that the 22' classics do believe they need the extra fuel delivery..

I already saw pics of his fuel system and believe me it needs to be upgraded..
The last time he ask for hels i gave him some advise and he picked up 10 mph...

Just trying to help FT :)..