Club Cobra - Tunnel Ports

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What are the pros and cons of tunnel porting? Isn't this similar to how hemi engines works? After viewing the fantastic EFI/tunnel port work done by SFFiredog, I'm really intrigued about this option for a 427 Shelby block. Is there a relationship between porting the heads and tunnel porting? What manifold would you suggest for a tunnel port for EFI, webers, and a single Holley carb? Thanks, I'm in the planning phase, trying to sort through the myriad of options!

Tunnel-port was an over-the-counter option back in '67 and '68 (for the 427) that consists of an intake and set of heads. TP heads must go with TP intake and vice-versa. It is called tunnel-port because the pushrods go right through the intake runner. This means that for the intake side, the mixture runs straight into the combustion chamber (no bending around the valve as is common for other engines).

The exhaust arrangement is tradional in all other senses. That is why this is not a hemi engine (valves not opposed for one thing).

The size of the intake ports is enormous--nearly as large a diameter as a soda can. They flow like gangbusters, and that is what they were designed for (high-revving)--very successful in NASCAR and 1, 2, 3 in Le Mans. Mine redlines at 6500.

Keep in mind, this was back in the sixties, and there are certainly other ways to skin a cat these day.

There were three manifolds made: 2x4 single-plane, 2x4 dual-plane (Le Mans), and 1x4 single-plane (360 degree style).

In a heavy car, one might give consideration to using the dual-plane. But, for a Cobra, you will have no streetability issues if running the single-plane (but it is a wives' tale, anyway).

Mike does some outstanding work and I believe he took a single-plane and converted it to EFI.

Bill, thanks so much for the info! What type of horsepower increases can one expect if they go with a tunnel port as opposed to using regular heads and a single plane manifold? Any suggestions on tunnel port heads? Are tunnel ports a popular configuration on today's 427s? Thanks again!

Bluedog

Blue, they are rare and not so easy to come by. I would start by finding a 427 first--they are not easy to come by either.

Your horsepower will be determined by many other factors, so a lot will depend on what other components you are using.

Like I alluded to earlier, there are plenty of less expensive options when building--something to consider early on in the planning process.

Bill's right on the planning part. I gotta ask though, why in the heck would anyone want to put 90's fuel injection on a 60's engine. Wrecks the look of the engine and no carb to tinker with on rainy weekends! :)

You want the best 427 wedge Ford ever made parts for, the TP is it. The best 427 was the SOHC 427 (in my opinion) and no slight entended there Bill. If I could have found the heads and manifold, mine would have been a TP. The power levels you can get out of a TP are truly amazing.

BTW Bill, how many times has that TP scared the He!! out of you? :)

Al

Al, Cammer is one of my favs also.

Your last question is harder to answer. This much I know--unlike many other things, where time kind of makes you complacent, if I am daydreaming about taking her for a ride and getting on it, my heart skips a beat. :D

Hey, I like any fast engine.

Hi Bluedog (I like that, Bluedog, Firedog, Bluedog, Firedog),

I'm just an hour up Highway 101 and I would be happy to make your tunnel port dreams a reality. Come see me when your wallet is too fat to fit in your back pocket and we can talk:D :D :D
Seriously, let me know if I can help you with anything,
--Mike

P.S. Hey Malone,
I'm still waiting for the call to pick up that cammer you want me to build for you!;)

SFfiredog, you have Email!