89 Caprice Issue

89 caprice 350 5.7hp.

Im pretty well mechanically recline, but I dont know the procedure on how to set the timing. I let a friend under my hood and he messed with the timing and now it wont run right.

I can can do the setting at longs I have a procedure to follow with.Thanks

there is a harness located near your heater core,on the passenger side,around the hood hinges.It is a single wire,circular male/female adapter that unplugs like any of the other computer harnesses,you lift up *gently* on the plastic clip and pull it apart.The plastic,circular shaped adapter is brown in my car.I belive it serves a brown wire with a white stripe.The purpose of the circuit it is conneted to is computer control of ignition timing.Obviously,its pretty futile to try to time the engine manually if the computer can override you.So disconnect it.Doing this will set a check engine light,so start the motor,get it warmed up to normal operating temp,THAN disconnect that adapter.Dont be alarmed when the computer stops controlling the timing and your motor sounds different.As you described,you already tried timing the motor without performing this procedure,so I guess your probably retarded by 6-8 degrees below TDC.Now time the motor with your induction light,being careful to follow your emmissions lable and set your timing to spec.The spec on my 305 is 0 degrees TDC.I am assuming yours is as well,but make sure you set to the specs on your VECI label.(the label should be on your fan shroud).Observe the correct timing under your light as someone secures your distributor.Dont set yourself too hot,as ping/detonation WILL result in the 89 models.When youre done performing the manual timing procedure,re-connect the computers' timing control harness.You will notice the computer kick back into control,however,your timing is now set correctly.Any concerns about playing with computer harnesses while the engine/power is on is mute,as this particular circuit was designed to be serviced this way.No other computer circuits on the car are,so remember that.The check engine light should cancel out as soon as you reconnect the harness,but if it doesnt,just leave the harness connected and turn off the motor,disconnect the negative side of the battery,and leave it disconnected for a few minutes to reset the computer.
Youre done. Now how about getting the most out of your ignition-HEI is one of the most powerful ignition systems around to this day,and with the right parts,can DRAMATICALLY increase your combustion efficency,giving you better power AND fuel economy.Shell out around 200 bones and get a MSD ignition coil,high end borg-warner ignition control module,a performance cap and rotor set,and a set of Accel 8.8mm plug wires.Use the OEM ACDelco plug,as they are good enuf for corvettes.Dont let anyone try to sell you a more expensive plug. Also,get a K&N air filter to feed more air into your chambers-now you have a 50%to70% more efficient combustion process.Hotter spark,better airflow.Time to use the high grade octane.You will get a dramatic increase in fuel efficency,but not so dramatic on low octane as high.The reason is that high octane gas ignites less readily than lower juice,burns hotter and longer,and produces more energy.Running high octane with an unmodified combustion system is a waste,as your stock junk cant ignite it nearly as well as the good shit. If you decide to upgrade,or if you have any questions,feel free to email me at [email protected].
As a note,its interesting that neither the chiltons or haynes service manuals have this information.Nobodys perfect.

Good notes on setting the timing. 0* is correct for the 89 5.7L as well per my underhood sticker...