The heat riser valve is in the exhaust manifold under where the carb mounts.It sends exhaust heat to the intake manifold. It is a 1/2 pearshaped weight at the side of the maifold above where the pipe hooks on. It should flop up & down freely. If it is stuck open the flat side will be at a 45o angle. Stuck closed it will be horizontal. To free it up spray the shafts with a penatrant & tap it back & forth with a hammer. There is or should be a coil sping on the other side. When working properly it should spring shut when you push to open. Marks on the dist cap should cause no problem & have nothing to do with timeing. Check the inside of the cap for carbon tracts. These would be a fine line between 2 terms. or to the center term. You may wan,t to replace cap & rotor just to be shure. Check your timeing after you put in the new points. Try advanceing the timing at the octane selector & see if it helps any. Check the top of the coil for cabon tracks also.

They say money can't buy happiness. It can buy old Chevy trucks though. Same thing.
1972 Chevy c10 Cheyenne Super
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