YES they do work well actually. I was on another form (Speedtalk) and Joe Sherman said that back in the 70's that this intake (actually the 198 NOT the 3933163) would run with whatever he was making from Edelbrock at the time up to like 7200 RPM I think. Some supergas gars were STILL using them. I'm hoping to get my '69 427 ZL-1 back soon and have one of my 3933198 intakes on it. BUT it's been heavily ported. Should be good to 8000 RPM now. I know the shop I deal with built a "Vintage" race motor for a LaMans series early Vette. If you look at the motor it looks like a stock 427 L-88 with only headers, but with the road race cam it made 730+Hp.

I spoke to the shop yesterday on my ZL-1, and I'm going to be taking my old ported '69 427/390Hp oval port 215's and see how they flow and compare to the '69 427/425Hp square port 840 heads with porting? I know how the oval port motor ran and about the power it made, so see IF the square ports are anything to run.