General Category > Quadrajet Carb Talk and Tips

Performance Rebuild/mods for Olds Gbody EM4 Qjet

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royalbobcat:
Hello, couldn't help but notice the good information rolling around this forum.... good stuff...   My general question is... I have an 84 Hurst Olds with an electronic quadrajet(EM4). I have been looking for someone who suggests/performs performance mods for these carbs. I have messed around with older Qjets but want to leave this one to a professional who has performance rebuild experience with these carbs...Thanks for the help.

omaha:
If I remember correctly from various replies on this forum, the electronic functioning of these carbs only affects the primary side. Mostly  cruise and low speed accelleration. The carb still has removable jets, accellerator pump and secondary rods. It does not have  primary side rods. The solenoid in the carb determines the fuel curve on the primary side. It really is just a q jet with electronic controlled
primary. All the same building teqniques apply except of course, the electronic functioning components. This would be the part that would make me nervous but, I guess all the electronic parts are available (I have seen them somewhere but cant recall exactly) Supposedly there are some cars like yours that are running very fast with the electronic functions still intact. The secondary side of the carb is just as "tunable" as the old Q-jets.  Not all of the mods in cliff's book would apply but alot of them would!
As far as tuning them for large cammed engines, it would seem like that would be the hard part. I would not know where to start. I know you can "sh#t can the electronic and just run them on the jets alone if thats what you want to do. Cliff has experience with them.

Cliff Ruggles:
The computer controlled units are excellent.  Same end result as with any other q-jet.  We've even set a few up to run straight off the jets for high HP applications in "stealth" mode.

The only thing the computer does is control part throttle A/F.  Idle and full throttle fuel are same as the older units.  They have a really nice adj upper idle airbleed deal, and one can adjust the "range" of the primary curcuit that is controlled by the ECM.

We've set up a LOT of them for later model cars where the owners have installed high performance engines into them, but want the stock look and all emission control devices in place and operational.....Cliff

royalbobcat:
That is helpful info regarding what ECM actually controls.... not too much. I have to admit when I recently rebuilt much of the H/O (engine, trans, front end) that I spent only $225 for a rebuilt carb. The car does not perform fantastic (what do you expect from approx 8.0 compression) and I know it will not ever pull like my 428 Pontiac but I am suspicious of my cheapo carb.  CLiff, what would be included in a performance rebuild of my original carb? I can call during business hours if you prefer.

As far as checking the functioning of my current carb, what are the easiest things for me to check? I have rebuilt engines but I have not delved into the world of carbs as of yet. Thanks very much for your input!

Cliff Ruggles:
What is the carburetor number?

Rebuilt by who or from what source?.....Cliff

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