A buddy of mine has an 87 firebird formula with a 305. The engine is carburated and has a computer. I told him to use the engine harness and just unplug the sensors and stuff. He wants to put a whole new top end in it and change the carb to a holley or edelbrock and not use the computer. Was I right, or is there more to it than that. Someone help me out here so he will shut up. He also wants to know if he has to change his gauges or not.

 

The computer also controls the ignition and converter lock up (if auto) so these things will have to be swapped out as well. Do a search and you'll find numerous threads that advise keeping the ccc-qjet and ecm. Whole lot of work for little or no additional performance.

If his car is an LG4 he'll need to tackle the exhaust before any other mod makes a diff.

 

I have a 1984 Z28 and I just dropped in a 355. I unplugged all the sensors for the computer and the car started and ran fine and then I took out the computer . All I had to do is put in a tc lockupswitch in and nothing else.As for the guages you should be fine there not hooked to the computer either. I would chage them there usally not accurate.

 

If your fbod has a ccc-qjet and the ecm/sensors are not connected it will start up and run but it's not going to run right. The ECM controls ignition advance on the distributor so you won't get full advance. The ccc-qjet will run full rich, all the time, if disconnected. Does the exhaust smell bad? Does it hesitate/stumble at part throttle transitions? Is it getting around 12-15 mpg? Does the glow of the service engine light get annoying or did it finally burn out?

Imagine how it would run with everything working right...

 

Whether that is a smart thing to do depends completely upon the use and other equipment of the car. If it is primarily a daily driver, the Holley doesn't make much sense (in my opinion, the Edelbrock doesn't make any sense under any circumstance - and that's a technical opinion, not a personal bias).

First, we'll assume this is a daily driver with an automatic transmission. He's already got the ideal carburetor, and any change would have the same effect on performance as flushing 6 $100 bills down the toilet. The effect on economy would be on top of that. The effect on driveability will be mostly the tweaking required to get an aftermarket carb to operate properly.

If the above assumption isn't correct, we'll modify it to daily driver with a manual transmission. In this case, the q-jet isn't ideal from a performance standpoint, but it is still the better carb from the economy standpoint. You could argue for a Holley/Demon mechanical secondary carb, but the Edelbrock or a vacuum secondary Holley/Demon is definately no improvement over the q-jet.

Finally, if neither of the above assumptions are correct, and this is a weekend warrior/strip/track car, then for the sake of consisency (ET racing) or autox, the Holley/Demon mechanical secondary is again the choice.

The carb is the absolute very last thing to change on these cars to improve performance. Until you get that into your head, you are chasing your tail and flushing $'s.

 

If he is getting a bran new top end with nothing computer controlled then there is no need to for the ecm or any sensors but temp. I have a 650 mighty demon and a mechanical hei distributor with a tc lock up switch and the car runs very well.

 

Again, getting a whole new top end with nothing computer controlled may not be money well spent. Depends upon more than just replacing things to be replacing things.