chris (04/26/83)
I must post this experience to the net so that it may help someone else. I recently had an engine built for my Cougar, which had a peculiar problem until recently. This engine was somewhat modified but was not a radical racing motor. But ever since it was finished it has run rough at an idle in gear, or while cruising down the highway. Now the cam which was installed was only 270 deg. duration on the intake, and 280 deg. duration on the exhaust so I was sure that the overlap could not be the cause of this roughness. The heads had been ported and polished, and larger valves had been installed, so there was a possibility of a sticking valve. However the compression was perfect in all cylinders. When I had the car tested on a floor dynamometer, we found that number 8 cylinder was running weak. We found this through the power balance test. This was confirmed by pulling the plug wire for #8 cylinder while the engine was running. The #8 cylinder just was'nt doing it's job. Well I went back to the shop which had built the engine for me, and asked them to check things out. After about a weeks time they called me with a verdict. It seems that on the Edelbrock Performer intake manifold, of which one is installed on my engine, they chase to position the fitting for the PCV valve in such a place that it feeds directly into the intake runner for the #8 cylinder. Since this was such a new motor, there was virtually no blowby, and #8 cylinder ran excessively lean. The fitting was blocked off, and the PCV system re-routed, and now the engine runs beautifully like it should. I'm sorry this is somewhat dragged out, but I felt it was necessary to include the details of the circumstances. I sincerely hope this will benefit someone as it was an exasperating battle to find this problem. Who knows, this particular type and brand of manifold may not be the only one with this problem. I wonder how many others may have the same thing wrong with them. Christopher Little Sytek Inc. Mountain View, Ca.