fleecerdog

Hello,
I have a 1987 Itasca 22' RV with the 454.I had a major power loss while driving thru Idaho last month. I turned around and limped 835 miles back home to Oregon on what I later found to be 5 cylinders firing. At the time of the occurrence I replaced both the carb and chassis fuel filter, plugs, plug wires, cap & rotor. No help at all. Once I got to where I could do something more I found the following:

150# compression on all 8 holes (under 5# difference across the board)

Pulled plug wires one at a time at the distributor and found #s 2, 5, & 8 getting plenty of spark but did not change rpm at all. I then pulled all 3 wires off and to the side ... so with only 5 wires connected the rpm and performance stayed the same.

Starts right up and idles rough with 18 inches of vacuum in neutral. Vacuum drops to near zero on any application of throttle. No flutter at all on vacuum guage needle at any time. Believe it or not I can cruise at 60mph showing 5" vacuum and even accelerate somewhat by flooring the pedal to kick in the secondaries, and still got 4.5 mpg.

Anyway, one final note ... about 500 miles into my return home the smog pump rail on the left bank burned a quarter size hole where the 4 small tubes join the larger pipe. Nice noise for the next 7 hours ...

Any thoughts on cause?

... I have not done anything else as yet ... not even pulled the burned smog rail.