Truck is not running right.

[79K10Crusher]

I have a 85 silverado. A few years ago I bored it 30 over making it a 355. It has ran great so far. Yesterday it started skipping and loosing power. I opened the hood and found a spark plug wire almost burnt in two.  I changed the whole set with accel 8mm wires and the truck ran fine this morning with no issues until it heated up after around 10 minutes. Now it's back to skipping again....anybody have any thoughts?

[79K10Crusher]

Truck is running at 180-190 degrees when this is happening.

[bd]

How did you route the plug wires?  Did you remove and check the spark plugs?  How do the cap and rotor look?


...I just can't quite get my imagination around a 'skipping' truck....   

[79K10Crusher]

Wires are routed using a proformance wire loom.  Spark plugs looked fine.  We use the term "skipping" when it feels as if we are not running on all 8 cyclinders. 

[bd]

...it feels as if we are not running on all 8 cylinders. 

Funny!  That's how I feel this morning.  lol

Did you check the cap and rotor?  If you have an ohmmeter, measure those brand new plug wires for opens then replace the spark plugs.

[79K10Crusher]

I am by no means a good mechanic. I just have basic knowledge of how stuff works.  What do I need to look for on the cap or rotor?

[bd]

I am by no means a good mechanic. I just have basic knowledge of how stuff works.  What do I need to look for on the cap or rotor?

Remove the cap from the top of the distributor, flip it over and visually inspect it for cracks in the plastic or irregular tracks that run between terminals (from unwanted arcing).  Inspect for excessive ash buildup on the 8 bare metal terminals inside the cap (some is normal) and for evidence of a burned carbon center button or heat stress in the area of the plastic around the center button.  Perform a similar inspection of the rotor.  Replace as needed.

[79K10Crusher]

Thanks for the help. Will do. I was just thinking it may be something else as the truck will run and drive fine but as soon as it gets up to temperature....that's when it starts doing it.  The first couple of minutes it runs it is fine.

[rich weyand]

Have you checked the timing?  What is it?

[bd]

Thanks for the help. Will do. I was just thinking it may be something else as the truck will run and drive fine but as soon as it gets up to temperature....that's when it starts doing it.  The first couple of minutes it runs it is fine.

It could be something else.  But, a rich mixture (when the engine is cold) requires less voltage to ignite than a lean mixture (when the engine is at operating temperature).  Is the engine basically stock configuration?

[thefarmboy21]

Sounds to me like you've either got your plug wires crossed when you changed them, need new spark plugs, or your coil is about shot.

[79K10Crusher]

Put new plugs in and that was the problem.  Only one looked bad. They looked old though.

[bd]

Good!  Thanks for letting us know.