Hi Richard. Yes they are great gaskets. Checked with straight edge all faces when removed and all fine. Its certainly sealing well, I have a great brake pedal, manifold vacuum A1. I'm sure its nothing to do with the gaskets, but maybe the carb. I left the carb on the manifold when removed. The port vacuum (suck) coming from the carb is non existent on idle, then, on low to moderate revs I get a very light vacuum, doubt it would operate the advance plate in the distributor. Would the vacuum be greater when the engine is under low down load? My understanding is that when the throttle plate is opened, vacuum from the intake manifold is transferred to the port in the bottom of the carb which then goes to the distributor and advances the spark, or does it, I'm still learning? Also, could it possibly be the cut off flap thingy in the exhaust manifold box? TIA, Jim.