How do you time a 1991 Chevy 305?

Answer 1

Remove the spark plugs and rotate the engine by hand until the #1 cylinder is at TDC on the compression stroke ( place your finger over the hole and you will feel air being pushed out past your finger if the piston is on the compression storke)ensure the distributor points to #1 if it doesn't rotate it 180 degrees. this will get the timing close so you can start it and use a timing light to set the timing to 6 degrees before TDC.

first you need to get electronic ignition module to base timing mode. your ig module will control timing and you will not time the engine correct. look for a brown wire located pass rear firewall by the-ac and heater box you will find a connector on this wire unplug it and you will notice your idle speed drops dramatically, now you can hook up timing light and set the tiiming the right way the module is no longer controling the timing so set it to rec. setting written on engine id tag under hood or on radiator schroud it should also tell you about timing set procedure once timing set and distributer tight plug in the btpass wire and your engine speed picks up and you set your timing the right way

Answer 2

You don't, the PCM does using info from the knock sensor.

If, however,a pud has removed the distibutor without marking positions you may need to set the base timing. Turn the engine to the TDC#1 position and set the distributor a few degrees (maybe 15ish?) before #1. Install the distributor and see if it lines up w/ #1. If not, pull it up and turn the rotor accordingly.

Oil pump drive mesh may make it difficult to push the distributor into place. If this is a problem, use a bigger hammer.

Answer 3

You have to use a scan tool and set it plus or minus 2 degrees of 0