Hesitation problem under load 454 Magnum, I need some idea's
 

Hi,

I have 21' Eliminator with a 454 Magnum carb, with CMI headers turning a 28" bravo.

The problem I'm having is while getting on plane it hesitates, coughs/sputters and once going runs fine.

It did "pop" once at half throttle 3500 RPM while going around 50 MPH

I DID change the fuel filer/water seperater (no change, in previous years that got rid of the problem)

I DID try another coil, no change.

Look forward to hearing some helfull idea's.

Thanks in advance

Accelerator pump in carb maybe

Check(lower) your float level and fuel pressure.

How would I check accelerator pump? And no fuel pressure gauge on the motor, how is that checked?

TO lower float, can that be done on the motor, or does carb have to be removed?

Thanks for the help!

To check accelerator pump, remove flame arrestor to where you can see in to the carb. Disconnect the throttle cable so you can operate it or have someone at the helm. Activate the throttle arm on the carb while looking in the carb. You should see a lot of fuel squirt down through the air intakes. This fuel helps the initial acceleration when throttle is mashed. Backfiring through the carb can blow the accelerator pump. It's a very easy replacement if it's a Holley carb, so you may want to change it anyway. Somewhere on the outside of the carb, you will see an arm that plunges down with a spring arm when the throttle is mashed. That is the accelerator pump. If you continue to have carb problems, take it to a good shop and have it rebuilt - it will cost a little but well worth it.

What kind of carb comes on these engines?

What about the filter in the carb where the metal fuel line comes in? Just an idea since you said changing the fuel filter would fix it in prevous years.
Jr.

I think it is a Rochester (it is NOT a holley)

It is the factory carb, but have heard the holley is nice upgrade.

Its either a Quadrajet or a Weber.

It does sound like you have a carb issue and if it were a Holley, I would say accelerator pump as well. I don't know enough about either of the others to give good advice.

If it's the Weber carb like came on my old 92 454 the acceleration characteristics can be easily calibrated by changing the step-up rods and springs. This carb is the same as the Eldebrock (Carter AFB) and a calibration kit can be ordered from Eldebrock with the exact same color-coded rods, various weight springs and jets. Much easier to tune than a Holley IMO.