81 with comp controlled carb
Thread Starter
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
81 with comp controlled carb
Is there an on line source/primmer on what doed the computer do in a computer controlled carb like on the 81? My understanding is that it controls fuel mixture, is this correct? So that after mods like heads, intake, headers, rejeting/needles wuold get it working in the correct range ?
Any advise would help
Thanks
Any advise would help
Thanks
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
Safety Car
Joined: Jul 2001
Posts: 3,921
Likes: 2
From: York PA
There is very little information available for tuning the '81. Although the carb was used in other vehicle the ECM was a one year only thing. If you search the forum there is alot of info available. Try searching for E4ME, there are a handful of members that have dealt with this system quite extensively. I know it's not 'online', but the 1981 Corvette Shop manual and Doug Roe's book - Rochester Carburators, have a lot of information about the system.
The biggest problem with tuning this system is you can't change the timing curve. You can change the base timing, but not the actually curve. As long as you don't change the vacuum levels too much the system will work great.
The biggest problem with tuning this system is you can't change the timing curve. You can change the base timing, but not the actually curve. As long as you don't change the vacuum levels too much the system will work great.
Safety Car
Joined: Oct 1999
Posts: 4,101
Likes: 10
From: NorCal
Pretty basic..
The Quadrajet on you car uses a solenoid (upper RH passenger side of the carb - blue plug) to control fuel flow. Its an on/off style solenoid that controls the main fuel delivery by varying the pulse rate of the main jet needles. It uses sensor input (throttle position, manifold pressure, O2 (oxygen sensor) to adjust the mixture.
Your on the right track, and you may be alright with the stock needle/jet combo, but bigger ones would work if needed. Good luck.
Hans
Your on the right track, and you may be alright with the stock needle/jet combo, but bigger ones would work if needed. Good luck.
Hans
Safety Car
Joined: Dec 2004
Posts: 4,071
Likes: 0
From: San Diego CA
The E4ME isn't what you'd call a high performance friendly carburetor due to the computer not being very tweak friendly. However, hypertech sells ECMs for it that are tweaked for different thermostats and such. You can get a hypertech ecm from Kragen but they're like over $100. The complexity of the E4ME is what drives people away from it and many, like me, end up just yanking the damn thing out and going with the M4ME and a vacuum advance HEI, which is the step before the E4ME and doesn't use a computer.
The system is pretty cool for like a daily driver or maybe a cruiser, but if you want to crank out a lot of horsepower it limits you.
The system is pretty cool for like a daily driver or maybe a cruiser, but if you want to crank out a lot of horsepower it limits you.
