I have a set of valve covers that have the same slope as the notched valve covers but they have the same slope all the way down. Any idea what they came off of?

 

I believe a photo would help a great deal with this question.

 

What do you mean by "slope"?

If they are five-bolt covers, they likely came off a 307. The 307 covers have a different shape than other Olds valve covers. The top surface is not parallel to the gasket surface on those covers.

 

I wonder if he means the notch runs the complete length of the cover? That's the way I'm reading it. If that's what he means,never seen that before.

 

I'll take pics of standard covers beside one of these tomorrow. From what Joe says they might be 307 but they have all holes like 455's.