may be vacuum leak.possibly carb base gasket. spray some WD-40 around base.if it smoothes out, replace gasket. also check plugs & wires. check cap & rotor for carbon tracking.a burnt/dirty intake valve can cause this also. first guess plug/wire.

I have an 84 pacearrow with the same motor. I had to replace the accelerator pump in the carb. at that age it mey need overhauling. especially if it sits most of the time as mine does. mine had the same problem.

the oil is probably from a pluged PCV valve

Anytime you are getting bad performance with backfiring, try cleaning the Carb. get a bottle of carb/ choke cleaner. Take the air filter housing off. make sure you remember to reattach all the hoses. You need to accelerate the engine so it doesn't cut out and spray liberally all the sides and use the tube to spray where the fuel is ejected. Be careful not to let the red tube drop in the carb. Cleaning the sides with a qtip and more spray will help the air flow smoothly and mix the gas properly. you can clean the carb intake barrels without taking the full cover and any hoses off, but you should clean the Choke side of the carb as well and you need to access the throttle arm and choke lever on the left side of the Carb to open the choke plates( they are almost always closed when it is idling. You have to play with each side of the choke plate bar arms, but you will figure it out. it is also good to check the points on the distributor. a small piece of sandpaper can give you tons of performance. If you have to replace or readjust the points a good temporary guage is a matchbook cover. The oil is probably from the backfiring or you have worn rings and are getting a large amount of Piston Blow-by from the valve cover vent. A way to test the blow-by is take off the oil filler cap on the valve cover when the engine is running. put your hand over and see how much is coming out. it shouldn't be much. cheers and happy Trails! -Peter

ran into this problem on an '84 Pace Arrow with a 454...look hard at the cap, rotor, plugs and wires, and pcv valve. when replacing the wires look for a GOOD set of 8mm wires as they are heavier and can displace more heat.

Anytime a gas engine fires back thru the carb, it is because a spark plug fired with an intake valve open (Timing ) or could be a spark jump between wires or a Rotor cap problem. If it is seldom. I would say plug wires. It it happens more frequently it could be atiming chain or? find a GOOD mechanis and let him fix it. Don't pay until it is repaired. get an estimate and discuss it before the job is started.It is expensive to try to guess and fix. A mechanics job is much harder also. LOL

All good answers. Put a vacuum gauge on it. A bad valve will show up in a heart beat as the needle drops to Zero.It will also tell U many other things such as "Timing". As we don't know what carb U have, it could be the "Power Valve". If it is, get the "Improved Blow Out Proof Version". Look under the hood at night for "Arcing Wires, Cap etc..

Hi, Ithink you might have a flat camshaft, or a broken or badly worn compression ring on one of the pistons. That maybe the reason why you have oil in the aie cleaner, or maybe the pcv is letting oil by.

I had a 1986 coachman(same problem). On all 454's, It.s the same problem. Have a 1997 georgie boy now,same thing. The spark plug wires cross fire. I bought 3m GLASS electrical tape and wrapped each plug wire and coil wire with it. Totally wrap each wire. Problem went away!!!!!! On the 86 years ago,I even melted the carb throttle plate before wrapping the wires.Start your engine at night and watch the light show, then wrap your wires.