First a little background. I put a Clifford 270M cam into my '78 200 engine. I bought this cam in 89 and ran it for about 25K miles in the early '90s in a stock 170 in my Falcon. Along with the cam, my 200 also had the head milled .060, valve pockets blended, valves unshrouded, chambers balanced and the carb inlet opened up ( http://i290.photobucket.com/albums/ll27 ... rface3.jpg ), along with prior headers, Weber 32/36 carb, '73 dist. When this cam was in my stock 170 it was very mild. With the bump up in compression, I was expecting a loping idle, but now I am unable to keep the engine running at less than (guessing) 800 rpm. BTW, to get the engine to run, I advanced the timing to 15 BTDC (harmonic balancer mark is good, it seems to want even more advance), screwed the idle speed screw in **all the way** (I can clearly see a major gap between the carb throat and the air flap) and upped the idle jet size. It feels and sounds like a vacuum leak.
I used an unlit propane bottle/torch and was not able to tell a difference in engine speed - even when I had the torch tip directly over the carb inlet. So I hooked up my narrow band A/F gage (I realize that it will not tell me much near the middle but it will show if the carb is at one of the extremes). The A/F gage is reading very rich - I would expect lean if there was a vac leak. Could this be why the propane did not speed up the engine.
I was expecting to have to rework the carb jetting with the change in cam and compression but I did not think I would have trouble to just keep it running.
I used an unlit propane bottle/torch and was not able to tell a difference in engine speed - even when I had the torch tip directly over the carb inlet. So I hooked up my narrow band A/F gage (I realize that it will not tell me much near the middle but it will show if the carb is at one of the extremes). The A/F gage is reading very rich - I would expect lean if there was a vac leak. Could this be why the propane did not speed up the engine.
I was expecting to have to rework the carb jetting with the change in cam and compression but I did not think I would have trouble to just keep it running.