It might/might not have a cam.A loping idle doesnt neccessarily mean a cam is installed.You can actually adjust the timing down really low & make it sound as if its got a cam.A vacuum leak can also cause the engine to idle rough enough that it'll sound like a engine with a loping cam.When a vacuum leak is present,it allows unmetered air (air that didnt get measured by the maf sensor) to enter the engine which then gets measured by the O2 sensor's.O2 sensor's have no clue where this extra oxygen came from,they just measure how much oxygen is present in the exhaust and output a specific voltage which equates to a lean,rich or stoich afr.When unmetered air (vacuum leak) reaches the O2 sensor's,they will trigger a lean signal & this will cause the ecm to (falsely) richen the fuel mixture in an attempt to bring the afr back to normal.This will cause the engine to run rich because the engine didnt really need extra fuel to begin with.Because of this issue,you need to repair the vacuum leak first thing.
(How To Check/Adjust Timing)
NOTE-Youll need to buy/rent a timing light.
Step 1) locate the timing marks on the harmonic balancer,use Witeout to draw a line on the 10° btdc mark.If youre standing in front of the car looking down at the balancer,mark the 10° spot on the right hand side of the 0° mark,not the left hand side.If you want a little more power and you run 91+ octane fuel,adjust timing to the 14° mark instead of 10°.
The timing scale will look like this:
10 ° ° ° ° 0 ° ° ° ° 10*
Step 2) connect the timing light
Step 3) start the engine and let it run until it reaches operating temp
Step 4) remove the spout plug from the ignition module harness,aim the timing light at the balancer and pull the trigger.
Step 5) if timing is not sitting at 10° or 14°,loosen the distributer holddown bolt (slightly) and rotate the distributer to your desired setting and tighten the bolt.
Step 6) recheck timing to make sure it didnt move while you were tightening the bolt, reinsert the spout plug and youre done.
(PICTURES)
1st=spout plug sitting on top of the ignition module harness plug
2nd=spout plug a few inches from ignition module
3rd=timing scale with Witeout mark.This is the 10° spot you need to mark with Witeout.If youre gonna bump timing up to the 14° spot instead,go ahead and draw a line on the 14° spot too,so it'll be easier to see with the timing light.
To make sure youve got the idle set to the correct position,you can follow the steps in this "base idle reset" procedure.Having the set screw adjusted outside of a specific range can cause the idle to surge also.This procedure will cure that.
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