Hey guys. I have a freshly rebuilt '67 Chevy 250 that has a miss in cylinders 3 and 4 at idle. Under acceleration and higher RPM cruising, it runs like a top. Everything on the ignition side is new along with a fresh carb. Compression is above minimum spec and all cylinders are within a couple PSI of each other. Manifold vacuum is 18" at idle.
My guess is that I have a vacuum leak in the middle port of the intake. I have tried spraying carb cleaner all around the port without success, but I can't reach the underside because the exhaust port is in the way. This thing is driving me nuts. Any help would be appreciated.
Thanks.
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