I changed the plugs in my HD last night. It looks as if the truck is running lean. I have been complaining about when I let off the gas the truck seems to defuel and the A/F ratio gauge drops off to nothing, then touch the pedal and it's back up. You can feel the truck like pulling backward, it's weird.
I changed the fuel filter @ 6,000 and again at 9,000 miles. It seemed to help a little. I have a K&N filter w/ stock modded box, Metco idler.
The denso's did seem to inprove throttle response and also the truck now hits 10#'s on the gauge. (More RPM's quicker)

My other problem is the famous oil in intake. The back of the throttle body has it caked on there. The upper phlenum has it all in there too. I'm going to clean the TB tonight and try an set the TPS to see if that may help. It acts as if the TPS is closing the throttle body when I let off the gas. While I'm there I'm going to clean and sand and polish the inside of the upper intake.

 

crockett59, this should answer your question in detail. Hope this helps.

http://www.ngksparkplugs.com/techinf...200&country=US

 

Thanks for the link. I feel a little better now, I was worried that it was running lean and I was going to have a major problem when adding my 4# pulley.

 

crockett59, you should have no problem adding a 4 lb. Lower Crank Pulley, as long as you have at least One Range Colder Plug and gap them no wider than .040 and no less than .035 if you are racing this vehicle. Hope this helps.

 

I have Denso IT 22's in there now and they are gapped at .035. I had a set of feller gauges last night and was afriad of breaking the tips on the denso's so I didn't want to mess anything up.

 

The a/f gauge should drop to nothing when you let off the gas. The a/f is probably around +14-15:1 when you aren't applying throttle.

 

crockett59 , from the What's it's Worth Department here, you only should be concerned with your Air/Fuel Ratio at wide open throttle, as any Tuner will tell you. You want to get them as close to 11.5 to 11.8, but never over 12.0 , as a serious Lean Condition, caused by excessive Knock Retard, can and will lead into Detonation, which could prove Fatal on one or more of your Pistons, with running high levels of boost and not having a good tune. Hope this helps.

 

Well I'll give it a whorl!!!! I'll probally get stuck on the throttle body and intake tonight, but if not I'm going to install my Pulley.

 

Here's a Denso link Scroll down for plug readings.

NGK BR7EFs too for me.

Dan