How do yu set the timing in a 1987 GMC Suburban 7.4 F.I 454?

Answer 1

I own a shop, and it depends on what you mean. There is a decal on either the radiator housing, or the hood that tells what the timing should be set on. There is a wire with a plug in it near the computer, that must be removed in order to adjust the timing. Use some white out, and use the little brush to mark the correct degree on the harmonic balancer, as this stuff dries fast, and is easy to see with the timing light. Run the engine until it is at full temp, turn off the ignition switch, remove the plug in the bypass, start the engine, set the timing, stop the engine, tighten down distributor, start engine, check timing again to make sure it didn't move, turn ignition switch off, re-connect wire, and you are good to go. The number one cylinder is what you hook the timing light to, and it is located on the drivers side (for rear wheel drive vehicles), on the fan side (for front wheel drive vehicles), and will be the cylinder that is closest to the front of the engine. If you are hooked to the wrong plugwire, you won't find the mark you made on the (torsional damper) harmonic balancer. All engines will time "before top dead center" and is on the damper as "BTDC". Zero (0) degrees is Top Dead Center. You may have to bump the starter many times to get the balancer in a position where you can clean off the scale, so if you have a buddy do the starter in quick, short bursts, it should move the balancer a few inches at a time, or until you can see where the marks are.
Glad to help out, Good Luck!!!

Answer 2

Remove the electronic spark advance wire to the distributor[usually Black with an Orange stripe]. Connect your timing light to #1 spark plug lead. Check for timing specs. on the decal on the air filter housing. Timing marks are directly below the water pump.
_ _ _