junkyarddog

basically,the car has been malfuntioning. at first the tach would "flicker" a little,and the engine would jitter and lack power. then it got so bad that the car would run,but once it started jittering,it was all F--ked up! it would seem to "oscillate violently" shutting off,then turning right back on on the highway!! then it just died.
I knew it was a computer problem,most likely having to do with the ESC (electronic spark control) on the HEI distributer.
earlier in the day I had adjusted the timing to get it to start,now I needed a more logical plan. I remembered the proceedure to correctly time the engine requiers the "4-wire harness" at the distributer (which is the ESC )to be disconnected. I disconnected that,got back in the car and started it right up!! idling perfectly smooth,with uncertainty,I put her in gear and drove away! WTF?! I guess the computer really does do jack **** for the engine!
enough of my rambling,I would like this post to be a tutorial for anyone in here with an L69.
my questions are: what does the ESC do besides use the knock sensor signal to retard timing as neccessary?
is the ESC part of the ECM?
what do those 4 wires do?
does anyone here have real schematics of the engine wiring?not like the crap in haynes & chiltons.

last question: since I'm converting to a holley 650 dp,mallory hyfire module & unilight vac distributer,accel super coil and no ECM,o2,knock sensor, ect. how good can I expect the engine to run? it is a brand new 305 HO long block,is the funtion of the knock sensor & ESC critical to the welfare of this engine as a daily driver? or is it just junk like everyone says it is?
does any one here have the real GM service manuals for this engine? (I'm all set with spending $90 on a book and waiting 6 weeks,when I already spent $600 on carb & ignition!!) I am determined to get to the bottom of this technical dilema,even though I'm taking the easy way out!.thanks

84TransAm

I put a 600 CFM Holley and a vacuum advance distributor on my 17 year old LG4 and noticed that the throttle response was much crisper, just incredible over what the Quadrajunk did for it.

ImportEater

Although I have no doubt that your car ran better with the Holley, it's not because the Quadrajet is junk. In fact when tuned right, the Quadrajet can be a fantastic carb. It has small primaries which is great for gas mileage, and large secondaries which are necessary for performance. The problem is that the factory never tuned the Quadrajet properly for performance applications, and that most aftermarket rebuild kits don't include the necessary hi-po mods to make the Q-jet shine. If this is your daily driver, go right ahead and remove all of the compu-junk, but grab a book and read up on the Q-jet. It will save you some money up front by not having to buy the new Holley; and your wallet will love you as you make that trek to work and back everyday

------------------
1985 Trans Am - rough and ready
1976 Corvette Stingray - not so rough, but always ready

junkyarddog

thanks '84TA and Importeater! I know the Q-jet has potential as long as it's in good shape and the ECM & friends are working right. I will run my car with the holley and aftermarket ignition for now,I'm keeping all of the stock stuff. the Q-jet runs but it has been on the car since 1984,the engine is new,so I think it should have a new carb with crisp ignition. in the mean time I will work with the Q-jet and HEI for performance(or just keep it in a box at my moms house!),the electronic spark control is malfunctioning,doing the engine more harm than good.that erratic ignition cut-off is sure to destroy the driveline. I'd really like to know more about the electronics involved in this system,because I don't trust that stuff,there's the TPS M/C soleniod,o2 sensor,knock sensor...I would use it if I knew what was going on,and had PROM burning capabilities.
I already took the q-jet off,and mounted the holley. I haven't hooked up everything,nor did the ignition,it should run with the stock ignition,but it would make more sense to do it all at once.
Importeater is right,the q-jet looks exactly like the holley underneath,the holly actuall has slightly smaller primaries and slightly larger secondaries,but thats only the throttle plates underneath,they are both 650cfm carbs.
I'd like to take the challenge and get the q-jet to perform,but I need my car to drive and I need lots of time and patience to overhaul that q-jet. espesially since I've never dealt with carbs before!
I know the holley won't be the most fuel efficient. I just like the look of the double pumper compared with the q-jet!! the intake is nasty looking inside too,so I'll replace that later. I'll let everyone know how it turns out,my car should be running tomorrow night or thursday night.