[bnun12]

Be sure to drill steam holes in the 307 heads for a 400sbc if you use the 307 heads

[cobalt327]

Here is a page on the 400 SBC steam holes.

[1Gary]

A 165 thermostat is more appropriate given the 400's steam hole cooling system.

Any crossover head in use,other than a 400,needs to be drilled for the 400's steam holes.

[mistagoodbadguy]

Ok so this is completely different then how I have always set up a carb fitting on the intake to the trans rear base to the break booster front to the pvc also I do kno the dates and will look at the wholes just I'm almost certin there the same ones iv always used

[mistagoodbadguy]

Stem holes have been drilled and heads resurfaced

[cobalt327]

Originally Posted by cobalt327

• You need a vacuum source for the PCV system. This is usually a larger port at the rear of the carb base.

Should read to the front port, not the rear. Rear can be the booster if you want or the manifold- it doesn't matter as long as its large enough and is manifold vacuum.