4.0 timing

[B2Mann]

Was outside today, tinkering with my truck, and was wondering what the timing
looked like. Marked the 10* mark on the crank shaft, set my timing light up and
started her up.

At start-up the timing read 10*then drops. While at idle the needle on the crank sensor is almost directly center between the 0* mark and
the 10* mark. Not sure if this is normal for the 4.0.

When unplugging the spout it drops more. Was reading other forums and some state that the crank pulley may have slipped on the rubber on the damper.

Also noticed when I hot rod it, there's a ton of spark knock. Seems to happen more when im in 3rd gear, than 1st 2nd or 4th. Almost makes in unbearable passing anyone. Gas mileage is normal, 21-22mpg. It's a 91 ranger 4.0 5 speed. 137k miles. Any help or input would be appreciated.

 

[Sasquatch_Ryda]

Carbon build up is the number one suspect to the pinging you are getting. Run some combustion chamber cleaner through it a few times and drive it like you stole it.

 

[B2Mann]

What kind of combustion cleaner is available? Besides seafoam?

 

[B2Mann]

Is the carbon build up on the tops of the cylinders or just on the intake and exhaust valve? Would removing the spark plugs and spraying Tb cleaner inside the cylinders be a bad thing?

 

[Sasquatch_Ryda]

I always just use Motorcraft combustion chamber cleaner as it's cheap through work and it works well. Get the engine up to temp and feed it in through the brake booster vacuum line. Just as you are about done the bottle, shut the engine off and let it soak for 10-15 minutes then take it for a good hard drive.

 

[B2Mann]

Just called a few of the parts stores in my area, and there saying they either haven't heard of it or they do not sell it. Would there be anything else that would be remotely as good or where would I be able to purchase it at?

 

[Sasquatch_Ryda]

Like I said, I get Motorcraft combustion chamber cleaner from the dealership I work at.

I know most autoparts stores will carry seafoam.