[tim_mc]

Update for 6/13/21. Truck has run well all week. Plug checks appeared to be hot/lean. I likely tuned the carb around a weak ignition in the past and now that it has been fixed I thought I should richen it up to be on the safe side. I went one step richer on the Edelbrock 1905 AVS2 metering rods. I was using 1956 rods, but swapped to the original 1449. The carb is now basically a stock AVS2 1905 but with .100 mains instead of the stock .101 jets. This is making a lot of sense to me after-the-fact. I wondered why it was so hard to get the right jet and rod combo to get this thing running decently. Now it's likely that I could have just bolted on the AVS2 out of the box with no issues if I had a great ignition on it to start with.

I re-gapped the copper ACDelco 41-629 spark plugs to 0.055" per DUI's recommendation (0.50-0.55"). Since I can't leave well enough alone, I swapped the cheap Delco plugs used to break in the engine with NGK FR5GP G-Power Platinum plugs (p/n 3248), gapped at 0.054" (that was the wire size on the tool). I'm a fan of NGK plugs from my dirt bike days working behind the parts counter at my local motorcycle shop as a kid.

I thought about going with ACDelco Rapidfire #5 plugs which have the required flat gasket seal and 0.750" reach, but I didn't like their resistance "range" of 6000-15000 ohms. NGK states a fixed 5000 ohm on their spec, and I'm looking for consistent spark on all eight cylinders. I also like NGK's fine electrode. FR5GP plugs are similar to the NGKs listed for my 2002 Z28 LS1 (TR5GP w/Taper fit and .708" reach), but with Flat gasket seal and 0.750" reach needed for the truck's Brodix heads. Finally, the NGKs are cheaper too at $3.69 vs. $5.59 each at my local O'Reilly's.

Test run to the gas station to top off with 93 octane. All is good - quick starts, steady idle, great acceleration.