View Single Post
  #34 (permalink)  
Old 10-09-2012, 04:56 PM
Tomcobra17 Tomcobra17 is offline
CC Member
Visit my Photo Gallery

 
Join Date: May 2011
Location: Freeland, MD
Cobra Make, Engine: Backdraft #188, Roush 342R
Posts: 26
Not Ranked     
Default

Dennis,

Mine are about 1 turn out, but my carb is different than yours and is probably setup differently from quickfuel as its a q-series 650. I have also changed the ifr's (and many other things as well) as it was too rich in certain areas when i received it. The q series is more of a race carb and your hr-650 is more street oriented. Im sure the metering blocks are different as well.

I was hoping that you had a card included from quickfuel that listed the specs of your carb so I could see how it's setup.

The best way to tune a carb for best performance is with a wideband. The hardest
Part of installing a wideband is having the o2 sensor bung welded into the collector of one of the stainless side pipes. I had a local welder do it for 40 bucks. Tuning takes time as well to make sure everything is right under all conditions. Going to a tuning shop would have cost a lot.......been there and done that years ago.

If you're willing to take a drive one day (where in Jersey are you located?) I'd be willing to make sure the carb is setup correctly and can show you how it works. If you had an o2 sensor bung welded into your exhaust, we could hook up the wideband and check the tune.

The basic way to setup a carb is to make sure the primary throttle blades are set such that the transfer slot opening viewed from underneath is square. Install the carb and set the throttle mixture screws to 1 turn out on all four. Start the car and adjust the idle speed using the secondary idle speed ajustment screw. Then adjust the floats so the fuel level is in the middle of the sight glass. Now fine tune the idle with the 4 idle mixture screws. Most people say to achieve highest vacuum, but performance engines with single plane intakes like a richer mixture in my opinion. Once the mixture screws are set, then you may need to go back and adjust the idle speed again with the secondary idle speed screw. The primary idle speed screw should not be adjusted once the tranfer slot is set correctly because it will negatively affect cruise and transition to the main jets if set incorrectly (too much of the slot uncovered at idle). It will also make the primary idle mixture screws insensitive to adjustment.

I know this is probably confusing ( it was to me in the beginning), but this needs to be done to make sure the basic settings are correct before the bulk of the tuning begins.

The link below is a very good article that does a great job of explaining "carb tuning":

Http://members.tccoa.com/392bird/tuning.htm

Tom
Reply With Quote