I owned a 1976 Allegro class A MH on a Dodge chassis, powered by a (I think) a 348 CI V8. The engine was a somewhat rare truck engine for 1½T trucks. Drove it from Indiana to Los Angeles CA and back, the only problem I had was blown exhaust gaskets. That issue was caused by carbon deposits on exhaust valves causing backfiring into the exhaust manifolds. I cured that with the use of Gumout carb and valve cleaner with the special carb attachment sold by Gumout. It replaced the gas line into the carb, then a full can of Gumout was inverted into the device. Then the engine was ran just enough to stay running, when it died the instructions said to let it sit overnight then reattach gas line and start engine. The engine blew lots of billowing gray smoke at first, then when it smoothed out idled noticeably better. That cleaned the valves and eliminated the backfiring.
