[Perry S (Spokane)]

Kind of an easy question. I have a 78 440 in my 70 Challenger. I had to pull the manifold for painting so I replaced the valley pan gasket with the type that blocks off the heat cross-over. This is a stock cast iron manifold. There is a passage in the bottom of each plenum. Should I cap or plug them? One is tapped and 3/4", one is not, and smaller. I seems that gas could collect in them.
Thanks,
Perry

[Dave-R (Roppa440)]

I think I would raher have any gas (petrol) collecting in there than have it drip into the cylinders and etch into the cylinder walls. So I would leave them alone. They should not effect normal running and any fuel in there would just slowly evaporate and mix with the normal intake charge.

[Dick Scaife (Chili440)]

I had the same setup on my 440, so I blocked the 2 exhaust gas crossovers with stainless steel plugs (used araldite) and then plugged the 2 small exit hole in the plenums below the carb with smoothed off round head studs (again, araldite !) It made an instant difference to the tune of the engine, easier starting and crisp running. I guess it was the loss of all that smog that made the difference. Also, I use a Carter TQ of about 850 CFM with no primary choke plate, and have never had any problems with unburned fuel accumulation in the intake manifold (I think the 440 drinks it too fast !)