Hi all. I'm having a nightmare with my 312, I just can't get it to idle smoothly.
Here's the history..
Fully rebuilt 312, everything new, done by myself ( a professional engine builder) . Isky E4 cam, pertronix ignition in a new distributor, new Edelbrock 500cfm carb.
Right from the first run , it would not idle properly. Eveything has been swapped. Complete ignition system, new coil, new leads, new plugs, all wiring checked for voltage. 2 different carburettors. Valve lash is 20'' hot. Ignition timing 10 to 12 degrees.
The engine will only idle rich to the point it stings your eyes at the tailpipes. The motor shakes as if it's misfiring. Sounds like it is but all ignition system has checked out good on a Sun machine. I renewed everything again just to be sure.
Compression test shows 180 psi on every cylinder . Cylinder leak down test showed 5% leakage on all cylinders.
Above idle speed motor runs smooth and pulls strong.
Anything I have overlooked? Spent all day on it today and got nowhere.