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if you know the proper timing for the engine, and it depends on the makeup of the eng. all 350's are not the same. you need a timing light. loosen the dist. hold down clamp,and with the eng. at an idle , shine the light at the timing mark over the harmonic balancer.if you have to change the timing, rotate the dist. very slowly ,and watch the timing marks with the timing light. when the right mark lines up with the timing pointer, lock the dist. hold down clamp, with the bolt. if the eng. starts running real rough, turn the dist. in the opposite direction.
There should be a sticker on the fan shroud telling you which wire to disconnect. On the older tbi motors it was tan with a black stripe i believe. Disconnect this wire, the loosen the dist. bolt and check the timing with a timing gun. Rotate the dist. until you get the desired timing then tighten the dist. bolt and connect the tan wire. On a vortec engine you have to have a engine scanner to adjust the timing. But if there is no check engine light on then the timing is correct all ready. It is controled by the computor, There is no ajustment needed.
the timing is computer controlled when there is no dist.---which became standard in 1987---previous to that you rotate the dist. and set it to the number of degrees advance that the decal under the hood says---some where around 10---the timing marks are behind the harmonic balancer (which is on the end of the crankshaft)
The rotor should be pointing at the #1 plug. If not, due to turning engine while dist was out, you will have to remove the dist. with dist out, you will need to turn the oil pump shaft that the dist sets in. use a long screwdriver for this
Remove Dist. cap turn engine if dist. don't turn its the timing belt. If not check elec. fuel pump.
hook up a timing light and loosen dist. hold down bolt, located at the base of the distributor. start engine and warm up aim timing light at timing marks located on driver side of timing chain cover. rotate dist. until timing mark is aligned with correct degree mark on timing chain cover. tighten hold down bolt and check to make sure timing has not jumped
If you have had the dist. out and have it back in now and the engine will start and run with no check engine light on then you are done, the computer will adjust the timing itself. If engine is running and the light is on , then you will have to get a engine scanner and scan the engine in the timing mode and adjust the dist. till scaner saids you are within the specs. then clear codes,tighten dist. your done.
check your timing sounds like its to advanced pull your vacum line off of your distributor andplug it then use a timing light to see where your base timing is it should be 10-12dgrs btdc if it isn't losen your dist and turn it sightly counter clockwise i think you will no if you went the right way when you put the light back on your timing mark it will have moved one way or the other once you get your base timing set tighten down your dist plug your vacum line back on to your dist and your done PS the engine must be warmed up and running to read timing timing marks are on the power steering side of the motor at the crank harmonic balancer
Check for excessive slack in the timing chain.
There is no timing adjustment on that year. Computer controls the timing. This is partially correct. The distributor can and has to be adjusted to set the cam retard offset. For this you will need a scan tool that does this.
You can set the base timing by ear, But to be able to get the check engine light to go out and to set the timing were it is supose to be requires a engine scanner. The computer controlls the timing on that year engine.
pull your timing belt cover/#1 plug/closest to the cover/ adj so piston 1 is at tdc crank timing mark should be in between pointer/ adj cam gear 1 mark at top with valve cover on 1 mark at right with top of block looks like L shape /put on belt and tighten tensioner/rotate dist to #1 caution dont hit pistons with valves when adj crank or cam for aligning timing marks good luck,