On the carb thing. The two big screws on the front of the carb are nothing more then the idle mixture adjustment. On this type of carb to adjust primary or secondary you have to change rods and rod holders to adjust the mixture while running. If you are making more power now you need more fuel. Turning the idle mixture screws wont do it. Find someone who knows the AFB carb and have them tune it. Your engine is giving you signs that somethings not right. Dont ignore them.

Ron

ok then

i use a home made pump ans a industrial GE motor...takes about 40-100 secs to pump it completly out...this thing will shooot cold oil acrossed the room!....i just got sick of time involved to change oil....everyother weekend is about max life for the oil....i got it down under 5min to do both engines....


check out a place the rebuilds electric motors...they got what ya need

"If you are making more power now you need more fuel"

unless the efficiency of the engine has gone up???

or how about if velocity has increased....thus more fuel threw the same orifice.

I thought you could add more fuel to it via set screws on the carb
I have alot of engine knowledge but minor carb knowledge
I thought the CFM was cubic feet per minute of air right?
the 750-850-950-980-1050 was all cubic feet per minute of air NOT denoting fuel delivery
what does a just under 500 HP engine require?
I thought 750 cfm of AIR was enough to feed a 500 HP ish engine.
Now rather foul plugs than detonate engine but really rather it just run and I can be done with all this horse **** to be honest with you
If it needs metering rods that is fine but have to let someone that knows this stuff do it.
I can attempt anything that is not the problem, I can probably figure out just about anything as well BUT when it can wipe out my engine I think it would be wise to let someone do it so I dont have to go through this hell again.
Jason

real fast can someone please explain if you have fuel starvation (lean condition) why that generates more heat in the engine?
Thanks
Jason

I installed a fitting/drain hose on my oil pan...run oil drain hose out transom plug, warm engine on the muffs to heat up/thin oil, drain into a pan while I work on other things...

Juat a suggestion...probably can't install now with engines in boat, oil mess to clean up. Just keep in mind if you ever pull engines again.

Zack

those drain hoses are fine if you have a single
good luck with twins being able to get that hose though the tiny hole in the stringer and out the back drain hole
Never happen with twins, cant get down there
Believe me I thought of that prior to dropping engines back in boat.
I wished that would have worked but no way no how can you get your arm down that far
thanks though
Jason

Jason,

A lean condition generates MAJOR heat...you have less fuel to burn with the same volume of air in the cylinder. Perfect ratio is 14.7:1. However, this is way too lean, especially for a boat and all things being imperfect. Max power is usually in the neighborhood of 12.6:1. Additionally, the fuel acts as a coolant on the variuos engine parts - valves, pistons, plugs, etc.

many factors...cid??...what is your max rpm??..what is the volumetric efficiency of the engine???...now factor in what it's going in??? how about cam selection???intake selection???


you oil is trying to cool the underside of the piston....which has an outragious serface tmp....exhaust tmp will range from 1200-1700 in a boat....from stuck pig rich to burn it down lean....so what do you think the the surface tmp of the source would be???HOT lol

Audacity is right about the efficieny. However its a general rule of thumb that to make more power you need more fuel.

The carb you have is basicaly a Cater AFB. Weber makes the marine version so its called the WFB. I think that if they came stock on 330 horse motors that they are only 600cfm. The two large screws on the front of the carb are for the idle mixture adjustment. These screws do nothing for the fuel mixture off idle. The carb is adjusted by changing the height of the metering rods in their holders. I think that you can change the length of the rods also. The Holleys use jets the AFB uses metering rods. If you suspect that you are having a lean condition at speed then you need to change the rod setting. Get someone who is familiar with the AFB to help you. They can be tuned to work properly. Most people will tell you to change to a Holley carb because thats what they know. More people will know how to tune a Holley than a AFB.

I know that you dont want to spend more money but you have got to understand that a carb for a 330 horse motor is not right for a 500 horse motor. At 600 cfm you are slightly under carbed for a 454 running 5000rpm. However the smaller carb will have better throttle response than a larger one and if drivability is more important than top speed the smaller carb can be tuned and run fine. If it were me I would buy two Holley marine 750's and start with the universal calibration that they come with. This universal calibration is usually too rich to make full power but safe for all but the most radical engines. Then you will have Holleys and every backyard hot rodder will know how to tune them. Once again you should spend the bucks to get a marine carb, ITS IMPORTANT!

Ron