Ford 427 Tunnel Port Engine
October 13, 2004
Recently I lucked into buying a single Tunnel Port 427 head. Some day I'd like to find the rest of the pieces and build one of these motors for the cobra. In 1967, NASCAR had put the kibosh to Ford using the 427 SOHC engine for stock car racing. So they wanted to try to get the SOHC engine's intake ports into a standard wedge engine, the problem was the pushrods. The shape and size of the intake ports was dictated by the distance between the pushrods and the need to wind between them. The solution was to ignore the pushrod and design the intake port where they wanted to and run the pushrod through a tube in the middle of the intake port of the manifold. As you can see from the picture below comparing the Tunnelport head with a Medium Riser, this produced huge intake ports lined right up with the largest valves used in the 427 (2.25" intake and 1.75" exhaust). They made a few different intakes for these heads, a single plane single 4v, a single plane 8v and a dual plane 8v. The engines were successful in NASCAR but also in drag racing and I've seen them in at least one GT-40.
November 3, 2004
Interesting theory, to make these high flowing heads more street friendly you could let them feed lots of cubic inches. For instance a 4.25 stroker crank in a 4.25 bore gives you 482 cubic inches. I think that is the most likely way I would build this motor. Probably with a single 4V of at least 850 cfm. You should be able to shoot for 7000 RPM and at least 600 HP I would think? On pump gas? (hopefully).