Never got the cam swap done due to some spring pressure questions, so spent the time servicing a couple of the cars and organizing (cleaning out) the shelves in the lower garage.

Now the question: I have an Edelbrock C427X manifold that I acquired years ago. From what limited info I have, I think this was a decent replacement manifold for the Chevy ALum High risers. This one had the open plenmum divider. Anyone have any comparative info on this manifold vs. a modern Performer RPM? I would assume these would be similiar.

The C427X is an old manifold from the 60's.It basically is a near copy of the OE GM alum high rise intakes.There isnt really much difference between the stock L-88/Zl-1 intake and the C427X.The Perf RPM
is a much newer design with a totaly different plenum / runner entry and runner shape.The plenum divider being removed basically just shifted the torque range up in the RPM range and killed the bottom end.... But L-88's were never intended for low speed use anyways.... If you are intrested in something in the 6500 and under range the RPM has proven its self a zillion times. The C427X was discontinued in the very early 1980's.... It's not a bad intake but simply suffers from the fact that it was a bandaid approach to things.When they needed a single 4bbl intake that would work to 7500 RPM back in the 60's the single plane intakes were still basically in the concept stage..they would really come to life in the early 70's.So they just took an existing intake and modified it.
Unfortunatly that never worked as well as they had hoped.Even Edelbrock didnt advertise it as a 7000RPM plus type intake...... Put a plenum divider on it and it should gain some of the low speed back and then you would have something very simular to the OE high riser used on the L-78's ect.

Thanks for the response. I bet I've had this in a box on the shelf for 15 years. It was ran at some point, but I never used it. Just wasn't sure if it was worth keeping or not.