i have a 46 fx that has a some sort of exhust problem.
its mounted on a PA edge 540, sideways (exhust outlet facing down), with a Slimline pitts style muffler extending out of the bottom of the cowl, about 1 1/2" past the firewall.
after a flight i get quite a build up of fuel over the firewall. the bottom of the cowl gets completly covered in a thick layer of burnt fuel, and i even get a little bit of fuel in the top inside of the cowl (BTW all the fuel has been burnt and used).
can anyone suggest were this might be coming from, or is it normal[&:].
thanks

It is normal for quite a bit of oil to be thrown from the exhaust system when the engine's running. Depending upon the airflow around the airplane, you can get large puddles forming in various places. It's normal to have to clean the airplane up after each flight, and after flying.

We've seen models that have literally large streaks of dark, burned oil running in large enough quantities that they drip off the model once it's back on the ground. You just pick up the rags (paper towels, etc.) and wipe it down.

If you have a lot of fresh fuel on the model, then you need to see if the tank's venting fuel overboard, or if it's being thrown from the carb or front bearing. A lot of fuel coming from the front means that the seal's gone, and you'll need a new case, crank, or both. The bearing does not provide a seal.

yeh i know its normal for oil to be spread very were BEHIND the exhust, but this model has a cowl and exhust outlets stick out about 1 1/2" behind the firewall.
i give it a run on the ground without the cowl to see if can see anyhting

My guess would be the muffler isn't mounted properly on the engine. I have this same engine and always notice more oil being on the plane from this engine, compared to my smaller engines and I also went ahead and installed a deflector which helped allot.

iv got deflectors

Unless the exhaust system pipes the exhaust stream far from the engine, it's still normal to get oil/fuel residue in the engine compartment. The carburetor will "spit" somewhat, there's almost always a small leak from the case/muffler join, and the engine will throw some oil from the front bearing. All of this is common, and normal...especially some oil from the front bearing. It won't get lubed if it doesn't have some oil pass through it. The front bearing is not sealed, but just has a shield against dirt.

You'll just have to clean the engine compartment from time to time. It's part of modeling when you use glow engines.

ok thanks for the advise