Lots of good input, and heat with a Kroil or wax seems like it's the preferred way to unstick the riser, so I'm going to try the torch this weekend and see if I can make it happen. I just got back from running it in the driveway to see if engine heat along with some penetrating oil would do its thing, but no luck. Will keep at it.
Performance issues:
1. Once the engine is warm, there is a noticeable chuff chuff exhaust sound that to my untrained ear is either a miss, or a valve issue (burned or sticky). I could be way off on my diagnosis, but I honestly have no way to tell for sure. So tonight, I pulled the valve cover while it was running, and the rockers had oil coming out of the weeps right away. I did not notice any valves that seemed to be hanging up. I'm not sure if one can tell if a valve is sticky by watching them run, but they looked like they were working fine. I spun all the rods with my fingers before I started it and all felt straight and smooth with no wobbling off center from the rocker, so I don't think have any bent rods.
2. When idling, I can feel the engine randomly bumping, like it is fighting itself. It's not sewing machine smooth, and the bumping becomes more random and more pronounced when the revs are up. I basically have an all new ignition set up.... The only thing I have not replaced is the distributor cap (which looks good) and I have not replaced the distributor itself, but plugs, wires points, condenser and coil are all new. It is a 6 volt set electrical system for now. I statically timed it to be 5 degrees, then gave it two more degrees for a total advance of 7. The vacuum advance is also new and is I have observed it to be functional
3. When I noticed that the heat riser was stuck in the heat-on mode, and read what the Chevy manual said about this condition, I thought the heat riser was contributing to #1 and may have been the answer to my plugs telling me that the fuel mixture was lean. The Chevy manual says if the valve is stuck in the heat on position, it will cause the gas mixture to expand (lean out) which can lead to detonation, overheating and sticky valves. I am no expert by any means just trying to do my homework and figure it out.
To be honest, adding a dual exhaust was on my wish list (guess I'm a sucker for eye candy and noise) and I was trying to convince myself that the stuck riser was a way to validate (and convince the wife) that I needed a dual set up... At the same time I'd be eliminating the dang flapper valve, but I am back to reality, and am determined to make the stock set up work.
On performance gains:
I don't have any illusions about a dual exhaust system turning a 95 hp vintage farm engine into a fire breathing beast, just thought it would be fun and eliminate the sticky flapper ;-). The truck as it is now, seems to hold its own in traffic but the chuff chuff exhaust sound has me concerned.
I am a fan of good engine noises and would rather listen to that than the radio.
