I've been thinking about this project for a long time, 10+ years. In that time, no one has come out with them, so this past summer I decided that I was going to do it. The back story on these tunnel port heads revolves around my cylinder head project. Last Spring, FINALLY, I started getting cylinder head and intake adapter castings from the foundry. From March to June I received about 50 intake adapter castings and 50 cylinder head castings, both the SE and the RE versions. Starting in late March I had the CNC machine running constantly, to try to get through machining all these castings, and by the end of June most of the heads that my customers had pre-ordered were at my local shop, waiting for seats and guides. Unfortunately this is their busy time of the year, so only some of those have been finished at this point; nevertheless it's been a big step forward compared to the last two years.
The other good news was that the tooling for the intake manifolds for my heads was done, and they were scheduled to be poured at the foundry in mid-August. This left me with a little free time, and a schedule target to hit in order to sneak some heads in with the intake manifolds. So with some encouragement from a couple good customers I decided to pursue the tunnel port project.
My SE and RE heads are set up with the same port location as a tunnel port, which gave me a huge advantage in designing my version. Because of this I was able to use the cope and drag tooling for my heads to also do a tunnel port version, and only had to change the 3D printed sand core. This saved a whole bunch of time and money, and accelerated the path to a completed head. From July into early August I spent a lot of time on the computer completing the design, guided by a tunnel port head that I had here. I have tried to make my version as faithful as possible to the original Ford part, while making some improvements to provide a better overall cylinder head.
Pictures of the prototype head are below (Note: behind the tunnel port head in a couple pictures are a bunch of raw castings for my SE and RE heads, which I just received a few weeks ago and which have not been machined yet; those are either going to people who have contacted me about getting some from the second production batch, or else going into inventory here). The tunnel port prototypes are bare heads; I have not yet had a valve job done or gotten flow numbers, but I would expect that they will flow very similarly to the factory cast iron tunnel port heads.
Here are the changes I made to my version of the tunnel port heads. Note that these heads would use the stock tunnel port intake manifold and rocker system, not a specialized system like my heads:
- The floor of the intake port has been filled in, to reduce the port volume and also improve the short turn to the valve. There is enough material in the casting to open the intake ports up to the stock size, if that is desired.
- Modern combustion chambers are machined into the head.
- The plug has been changed from an 18mm taper seat plug to a 14mm, gasketed 3/4" reach plug. The plug location has also been moved. Hopefully this will eliminate the cracking issue between the plug hole and the intake seat that the factory heads suffered.
- The guides have been changed from 3/8" stem to 11/32" stem.
- The exhaust bolt pattern has been changed to the Cobra Jet style.
- Accessory mounting holes have been put on both ends of the heads, not just one end.
- Large inserts have been put into the rocker stand bolt holes, to withstand more spring pressure.
- The intake face of the casting has been thickened, to avoid the cracking on this face down near the deck that is often seen on the original heads.
- One other modification that I may make, if some customers are interested, is to replace the exhaust port design (which is basically like most other FE exhaust ports), with the one from my SE head design. This will make the casting around the exhaust ports look different than a stock tunnel port head, because of the shape of the port itself. However, it would result in flow of around 250 cfm, rather than the sub-200 cfm flow of a standard FE exhaust port.
I will be displaying the prototype tunnel port head at the FE Race and Reunion September 7-9. I am also planning to take advantage of the foundry's recent performance, and order a small production batch of tunnel port heads at the beginning of October. The raw casting design needs a couple of tweaks, but I expect based on the prototype castings that they will come out looking good. See the link below if you are interested in getting a set. And as always, questions and comments are welcome - Jay
https://fepower.net/simplemachinesforum/index.php?topic=11822.0
