Resurrecting this one because I stumbled on a post about stuck heat risers potentially causing a lean condition if they freeze up in the "heat on" position. So I popped the hood and tried to twist the heat riser counterbalance by hand... and it appears to be frozen in the horizontal "heat on" position. From what I have read in the forum and in my manual if the valve is stuck in the heat on position, the manifold gets too hot, the gas expands too much and creates a lean condition. My guess is that the PO drilled out the jet so large to compensate?
I've been soaking the riser shaft with PB Blaster and lightly tapping back and forth with a hammer to get it free and no luck so far. Hopefully, I can free it up, then do a highway run re-test on the spark plugs to see if it runs a little richer with a functioning heat riser. If I get the riser working again, I wonder if it will then become a rich condition. Will pull plugs and see.
Also have what seems to be a sticky valve or two because I am getting a constant chuff chuff sound once it warms up. Any thoughts on how to fix them? I'm trying some MMO on the stems, and read about spraying Kroil on the valves, but I'm worried it will catch on fire or something.
Thanks!
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