running out of gas on top end

[chaparral2350sx]

I currently have a chaparral 2350sx and a new 454 with +.040 overs with a 9.5 to 1 compression, cam is a .500 lift on intake .510 on exhaust running a 750 quadrajet orginal carb.I know that it is running out of fuel on top end (4900/5300). As of now I can only get 4900rpm out of it. should I change needles in the carb or switch to a marine Holley.Oh yea the motor was a 454mag before I got a hold of it.Please help with this problem.forgot to say fuel presure is fine 5 and a half to 6 psi.

[Fiat48]

Check your fuel pressure at wide open throttle. Move the gauge if necessary so that you can read it at maximum RPM. If you have fuel pressure of at least 3 lbs, then you are not running out of fuel and larger needles and seats or fuel pump is not the problem.

[Hotcrusader76]

Originally posted by chaparral2350sx:
I currently have a chaparral 2350sx and a new 454 with +.040 overs with a 9.5 to 1 compression, cam is a .500 lift on intake .510 on exhaust running a 750 quadrajet orginal carb.I know that it is running out of fuel on top end (4900/5300). As of now I can only get 4900rpm out of it. should I change needles in the carb or switch to a marine Holley.Oh yea the motor was a 454mag before I got a hold of it.Please help with this problem.forgot to say fuel presure is fine 5 and a half to 6 psi.
Switch to a Holley bro! They're easier to tune and modify! I can get you set-up with a custom model when your ready.
Hahaaa....not a biased a opinion at all!
Thanks
Ty Lofstrom
TPC Racing
sales@tpcracing.com

[Infomaniac]

Try taking the fuel filter out of the inlet. If the pressure is good this is probably dirty or too restrictive. Raise the float level also.
Buy a Holley when you get a chance.
I have seen many times the fuel supply line or the tank fitting is not large enough. Make sure the anti siphon valve in the tank is not holding you up.

[chaparral2350sx]

Yea Guys:
you have the same idea I do about the Quadrajunk.The idea about the anti siphon valve would be vaildated if the fuel presure drops off at 4900 rpm if the fuel presure is good and I am still running out of gas we all know what to do. Sell the Quadrajunk on Ebay and buy a Holley. which is what I want to do in the first place.Thanks for the ideas and I will find out this weekend if the fuel presure drops off on top end as soon as my budy gets in the boat and watches the fuel presure gauge while I drive.
2350sx

[Infomaniac]

Don't forget about the fuel filter. It is after the fuel press gage !!!!!!!!

[Hotcrusader76]

Originally posted by chaparral2350sx:
. Sell the Quadrajunk on Ebay and buy a Holley. which is what I want to do in the first place.
Hey! When your ready drop me a line or email me, and I can get you set-up with a carburetor.
I will send you a form that you can fill out for the engine specification questions.
Thanks
Ty Lofstrom
TPC Racing
sales@tpcracing.com

[chaparral2350sx]

HI Hotcrusader
I did find out that fuel delivery is not the issue it most likely is in the jetting. You said you could help with jetting a carb to my boat. I will give you my email address and you can give me a ballpark figure on how much it is going to set me back.Thanks guys for all the help and I will keep a eye the forum for good info.
Thanks
burn4602@bellsouth.net

[CV-23]

If you go with a Holley, make sure its a 800cfm. The 750cfm Q-Jet is good to 600hp according to Dennis Moore so don't count it short. I'm a Holley Fan but the Q-Jets work fine and are easy to tune with less fuel mess. They are sensitive to vacuum changes, something the Holley Double Pumper is not....Mike.