Deciding on replacement intake (318, details in post)

You stated that your car runs healthy and pushes the car along nicely. I took this as such that the person that built the engine matched parts and put together a good combination. Even if someone else added the tunnel ram with dual quads later, it takes good bit of knowledge and experience to tune that setup, especially for the street. With this in mind, I believe you will decrease performance going to a single 4barrel manifold setup, unless your car does not perform as good as you think it does.

Compression does matter, the more it has, the more horsepower it will make. That doesn’t mean your car won’t be quick, but it won’t have the horsepower to mph.

Case in point. I have a 68 dart that had a teener in it with a stock x head top end on it with the exception of a holley 650. It had a wild crower hydraulic cam and 4.55 suregrip. It ran 14 flat in the quarter mile, matter of fact I had it into the 13’s with a looser converter but it kept busting transmission tail pieces cause the frame/unibody was not stiff enough. But the car hit the eighth mile mark at 100 mph and would not go any faster cause it didn’t have enough compression. Low static and when you added in the cam overlap, the dynamic compression dived.

Food for thought.

Expanding on the conversation then, I will get compression readings over Xmas. I cannot comment on the state of tune of the tunnel and carbs as do not know how well it is set up, a dyno run would give that info and tbh I hadn’t considered it. How well would a cross ram intake (if they’re available) weigh up?

And yes, agreed - performance without figures is a subjective thing.