I have an exhaust leak for sure, hope it is just a gasket and not a crack in the exhaust manifold but not sure if the intake is leaking at the head. My 1964 225 automatic is running somewhat rough, will idle fine when first cranked at approx. 1000 rpms. Once warm it will start to miss but only a little at 650 rpms. But when accelerating will stumble and can go dead if not babied taking off. I have had the carb rebuilt and put in new plug wires, plugs, coil, petronics in place of points, new fuel pump, had valves adjusted, compression checked out acceptable. I am thinking the intake gasket may be sucking air at the head just wondering how to check this?
Thanks

If you have to baby it, that's usually the acc pump...

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Well that may be it because the accelerator pump appears to be leaking somewhat as I just posted about fuel moisture on the intake manifold. Should I get someone else to rebuild (wish I could but not really an option if I want it correct).

You may have this fixed by now, but to check for a blown intake gasket, leave the motor running, spray brake cleaner, or electronic cleaner around the ports on the manifold where it bolts to the head.
If it revs up a little, or you can notice a sound difference it's blown