Cylinder Heads. All two of them
This is what all of the fuss is about. The 427 SOHC engine is basically a Ford FE 427 Side Oiler engine with some whacky heads on it.
Ford had a winning history with the 427. They had engines known as the low riser, medium riser, high riser. All of these were progression to get more rpm out of the basic 427 engine. If I have my history correct, the high riser engines were banned because they were too tall and had hood clearance issues. The Single Overhead Camshaft head was just another attempt to increase rpm and gain some horsepower for the NASCAR ovals and fit under a stock head.
Not to make it sound like Ford just took the previous years 427 and slapped new heads on it, they also upgraded the 427 blocks oiling system. The existing design had priority oiling to the camshafts and heads, this new system prioritized the main journals, the block was known as the side oiler. Both the heads and block came out in 1965.
Ford was doing well with the 427 High Riser. They were very successful in 64 and then NASCAR banned the engine before the 65 season. With a short development time, Ford decided to take what they learned from their 255 DOHC Indy car engine and go to a single overhead camshaft design for the 427. It’s reported that they had a running engine in just 90 days
Yes Gladice, those are hemispherical combustion chambers. Only difference between these and the Mopar version is the placement of the spark plug holes. Chrysler located theirs nearly dead center of the combustion chamber right between the intake and exhaust valves. Ford has their plugs off to the sides of the valves. I’m sure Ford would have preferred to go right through the center of the valve cover and combustion chamber like Chrysler but they had to contend with a freaking camshaft sitting in that location on each head. The Ford spark plug route is very similar to the modern day 4.6 Modular engine where the coil pack appears to sprout from the top of the head somewhere between the valve cover and the intake manifold.
No lifters or pushrods to deal with, just some funky looking rocker arms with a horrible ratio of. 1.3:1. The small block Ford used a 1.6:1.
The heads were originally cast iron which brought them in at around 80 pounds a piece. That’s about the same weight as a cast iron BBC heads and like the BBC, this can be cured by replacing these behemoths with a set of Aluminum heads. Not the cheapest way to go but to be honest, there is no economical anything when it comes to the 427 SOHC engine.
Tah-Dah! Each of these are about 45 pounds. Nearly half the weight of the cast iron ones.
I was able to use the same valves from the cast iron heads. These are Ferrea hollow stem valves. The old style valve head design gives a little power away compared to a more modern tulip valve head design but the Ferrea are hollow stem. The original valves from Ford were sodium filled hollow stemmed. The sodium was used on the exhaust side to help keep them a little cooler. If you find an original set of these, don’t use them. Sodium is corrosive and the valve stems will probably snap in half. The ones I have seen have black marks on the stem which indicates that the sodium filling is eating its way to freedom.
The valves are a little over sized from stock at 2.35 for the intake and 1.90 for the exhaust. The valves stems are a tad smaller at 11/16 compared to 3/8 for stock.
A performance mod that racers discovered was a D shaped exhaust port. Rounded at the top and flat at the bottom. The design is supposed to promote better flow. The Cammer has D shaped exhaust ports but they’re upside down. I’m not sure why this is. I didn’t design them but I did hear that the exhaust port is flat at the top because there wasn’t enough material at the top to allow a more rounded shape. I think the D is a mistake and even if Ford had the real estate to do the port with the proper D shape, they probably would have preferred a round port…or not.
For the Robert Pond heads, which these are, the exhaust ports are raised about a half an inch. I suppose this was done to straighten out the exhaust runner slightly. I was told that Jon Kaase helped Robert Pond develop the ports so these aftermarket heads flow a little better than the stock ones.
This is the size of the intake port. I haven’t worked with many engines but to me, these are freaking huge.
I think some of the aftermarket BBC heads flow as much or more than these heads do. I think I even heard that some of the LS heads can be massaged to surpass them. I could be mistaken but I thought I read that the stock intake ports move about 320 cfm. I don’t know how this compares to the aluminum Kaase ports, hell, I’m not even sure about the 320 I just quoted. Being a street engine, I’m actually more worried about the ports being too big as opposed to which engine flows more.
Update: I did some searching and found that the RPM aluminum heads flow 393 CFM of air at .700” lift on the intake and 270 CFM at .700” lift on the exhaust.