lookin for some suggestions...

[quig]

hey guys !!!! long time no post but I got a question maby someone here can help me with...
the Q-jet has a real "flat spot" comming out of the hole ... I'm not sure if that is the best way to describe it but its not a motor issue, the motor will turn up hard and quick then settle in and the hole shot will occur( the boat will begin to move hard) I would like to take that hesitation out ... any comments or suggestions?????
background: glastron CVX-20 berk 12JF A Agressor impeller all new this past spring 429 BBF dyno'ed @431 hp around 5600 rpm HELP PLEASE :D
http://free.***boat.net/gallery/Reader_Rides/Jet_Boats/Im000315.JPG

[Rexone]

the motor will turn up hard and quick then settle in and the hole shot will occur( the boat will begin to move hard) I would like to take that hesitation out
It sounds as though you may have a pump cavitation or loading problem and not a carb problem if the motor actually revs up but doesn't move the boat. 2 things I know of that can cause a Quadrajet to have a flat spot (which doesn't sound like you have) is a bad accelerator pump plunger seal or an improperly adjusted secondary air valve spring.

[quig]

sorry I was not clear ... the motor runs fine but the boat has the dead spot when the throttle is activated ... the motor revs but the boat doesnt react until a few seconds later... is that cavation? if so how do I stop it... short of not hammering the throttle is there something I can buy to correct this ?

[1HOTGMCJET]

quig:
is that cavation? if so how do I stop it... short of not hammering the throttle is there something I can buy to correct this ?Sounds like it, Quig - you may want to give Don's Pump Service www.donspumpservice.com (http://www.donspumpservice.com) a call - his "cavitation reducer" may be just what you need - I believe Duane Oblander www.hi-techperformance.com (http://www.hi-techperformance.com) installs them as well - Good Luck! :D

[Rexone]

quig, The cavitation reducer may or may not be the answer. My suggestion would be to PM me your phone number and I'll have one of our jet techs call you on Monday to try to get to the bottom of it. Here's a link to the cav reducer.
http://www.rexmar.com/page116.html

[Froggystyle]

I would definitely take Mike up on his tech line.
That being said, I too am running a large-ish jet boat and had cavitation issues. I am now running a DPS inducer (reducer.... whatever!) and have no more cavitation issues. I seem to have picked up a few mph too with the Agressor "B" impeller.
Who knew?

[ChetCapoli]

Froggystyle:
I seem to have picked up a few mph too with the Agressor "B" impeller.
Who knew?Who knew?...hmmmm..if i had to guess it was HBJet. No offense frog but if you were me i think that would get ya going a little bit dont ya think? :) Glad to hear someone else with aggressor results for once besides me. Hey quig, i would double check your clearances on your pump seeming you just put it together, i cant even spin that rpm with 700hp with a B impeller. Still working on it though.
CHET

[wsuwrhr]

Check your accelerator pump. It should squirt gas the instant you touch the accelerator. I'm sure this is it.
Brian

[quig]

thanks for all the input guys !!! I have just sent Mike a PM maby one of his guys can help but forsure its in the pump as the motor turns on instantly and the boat just wont move with the RPM of the engine and thanks Chet for the heads up on the engine rpm thing it turns out my tach was reading "off" by around 850 rpm in a comparison with a Snap-on digital, the true rpm was more like 4750 at WTO sorry for the mis information but glad to have got the one problem fixed now if I can get the damn thing to hook and go forward I would be a happy camper :D :D