18MPG in my LIFTED burb this weekend! And a problem...

[redz 1970 K5]

So, on Friday I installed my MSD 6A ignition. I had the headers installed on Wednesday and then I put the MSD 8.5mm Super Conductors Saturday.

I took the truck on the highway on Saturday, and no kidding my MPG was 18!!! 270 miles, 15 gallons. I topped off before the trip and topped off after the trip. My odometer is right on too. 65MPG and I even got on it a few times.

These mods definitely had a large impact on mileage since I was around 13MPG pre mods.

I only have ONE issue, and it isn't an easy one... Since I installed the headers in particular, I have a light pinging in low rpms off idle. When I am taking off from a stop, it pings off idle, probably between maybe 1000-1500 and then it doesn't ping anymore or when shifting gears??? I checked my advance, truck is at base timing and my ignition is for the most part new. Can a lean or rich condition cause pinging? I am thinking that the O2 sensor (brand new) might not be reporting the A/F mixture correctly to the ECM now because of the headers. I don't know what else it could be.

I will probably run some of this fuel down, run a 91 and see if it goes away. I am currently running 85, which is usually ok and what I have been running for months. The headers did something and I am scratching my head...

Here are a few pics of the goodies.

8.5mms


MSD


Cool mini tach that I will put in the corner in the A-pillar and dash; SOOO nice to track RPMs again.


ANY, and I mean ANY ideas on my pinging problem would be much appreciated... Thanks!