Engine sounds like there's a hole in the exhaust but there isn't

[culp]

My 1970 Traveller has a very raspy exhaust note coming from under the bonnet like there's a hole in the exhaust. I've been right over the exhaust pipe and there's nothing wrong with it, no holes. I'm thinking it's an ignition timing problem?

[oliver90owner]

My first thought would be to inspect the exhaust system in front of the exhaust pipe - like manifold and joints.

[simmitc]

I can't see an ignition problem making a rasping sound. I would concentrate on the carb area. The air filter should have an inlet tube that acts as a silencer. If this has fallen off then it can sound like an exhaust noise. When cold, try wiggling the exhaust pipe to see if it is loose - it should be rock solid. Also look for tell tale streaks of soot/carbon. With engine running, and taking great care to avoid moving and hot parts, listen/feel for a blow in the general area around the manifold.

[dalebrignall]

check the mainfold clamp is there a leak between the manifold and the down pipe it might need some gun gum round the joint

[culp]

It's pretty hot around there, but there is no sign of a leak around the manifold or the exhaust/manifold join.