I am a novice builder and I have a 1971 cleveland 351 that came out of a cougar I think.?? I have put a edelbrock performer intake manifold on it. There are 2 small holes that are not covered by the manifold or the valve covers. The holes are just under the valve covers one on each side. Is this normal??? Also the valve covers I purchased do not have breathers. Is this a problem..thanks for any input

For the breather issue, YES, it can be a big problem. Your engine must have a way of releasing blow-by gases from the crank case.

If these are not present you will quickly blow out the crankshaft seals and blow oil all over the road.

Every single Cleveland engine I have ever seen relies on such breathers. Some cheapie aftermarket valve covers had knock out plugs in each valve cover, where you knocked them out and installed a rubber grommit and a breather cap.

Usually you knock out both; one is used for the PCV valve and the other is a breather.
If there is no oil filler cap, the breather is also a filler cap.

I wonder if your valve covers are from a non - Cleveland engine.
Some older Ford engines had an oil filler pipe at the front of the engine with a breather on top. In these engines, the valve covers had no breather.
This might explain the hole you see. All the photos I have of Clevelands show no small holes on top of the engine that are not covered by either the covers or the manifold or distributor or thermostat housing, so maybe the wrong covers are leaving something exposed?


Can you post some pictures??