Progress - but not success

Post date: Jul 16, 2012 1:52:22 AM

A long break for a quick vacation out to Sedona, some more machine work, then another test run.

I suspected the intake was leaking from the underside due to oil in the intake and the heads - and the idle problems. I don't have a proper straight edge, but some basic checks with a square showed it wasn't quite right. Checking it out at the machine shop showed about a 6 thou bow in one side and 3 thou warp in the other. They get it on the bridgeport and one side was actually bowed 15thou, with the middle (lengthwise) sticking out.

I also got three sets of intake gaskets - normal SCE, Flatout, and Cometic. The Cometics aren't in yet. The Flatout are slightly more compressible and covered with a slick silicone, while the SCE are plain composite. The first set was SCE with the silicone bands, but I think the bands actually got sucked towards the ports. The gasgacinch did not impress, so I tried the aerosol high tack. Fingers crossed.

Got a new Pertronix III module, tossed it in, and guess what? Exact same problem. Intermittent on 4 and 7. Switch back to the old dizzy, no problems. Went ahead and tried different wires and plugs, but no change. Very frustrating. I'll see if Pertronix can do a full unit exchange or something. My machinist mentioned that he's see lots of failures from them in just the past couple of years. I'm in around $450 at this point on the ignition, so I really hope it's not a lost cause.

So obviously the test run wasn't going great yet. Still cannot get a decent idle below 1000, but made a few minor gains today. Main change was to open the idle air bypass to 0.110". Previously was around 0.050". Since I'm starting with a 7042250 (350 carb), I keep forgetting that there are other mods to make it more friendly to big displacement. May also need holes in the throttle plates... A 0.110" hole in the bypass looks quite large. Still have nozzle drip and the blades are open about one full turn of the idle screw further than I'd like it. As mentioned, that keeps it at 1000. Any less and it goes through a surging cycle then dies.

Of course, who knows what state the ignition is in as well. Frustrating.

So I'm going through the carb one more time to make sure I haven't missed anything else, and the next run will probably use my old cap and coil just to rule those out as well.