Hi James,
The low risers are common to just about all the FE versions out there from 1958 on. Those were all low profile intakes, and some of them were designed for truck use and some were admittedly not intended for high flow or high power. The head design, however, is a very good one, and the entire big block “FE” family was intended to be the “power option” for Ford Motor Company. The series included great motors like the 360-hp solid lifter 352, and the 401-hp solid lifter 390, the 405-hp 406, and of course the 427 too. Most of the cylinder heads that fit the 352 will bolt directly onto all of the other FE motors, including the 427. It’s a great design, and Chrysler Corporation also had some great wedge head designs like their 413 Max Wedge, and their 426B (non hemi) that had great (primarily drag racing and street racing) careers.
On the low rise Ford intake, you get the same basic (good) cylinder head we have on our boats, and a squashed down intake design (resulting in a flat motor) that fits under a hood of something like a 1963 T-bird. As Ford continued to experiment with power options, they found that bigger ports on the intake side produced more power. Since the motor couldn’t really get any wider without a total redesign of cylinder placement, they started building taller to achieve the same end result. The ports got taller within the same cylinder spacing and bore, etc. In other words, they increased the air flow by making taller ports with more flow and longer runners. The Chrysler “cross ram” design used long runners too, in order to build very large torque numbers.
Everyone of the era (the 1960’s musclecar war era) knew about this basic technology, but Ford is the one who built the bullet-proof designs that swept wide-open-throttle big block racing like NASCAR. The Chysler hemi is (also) a great motor design, and it was very competitive, and it was designed from the onset to compete against the 427. When Richard Petty jumped ship and drove one season for Ford, Mr. Petty won in a 427-powered Ford, and he raced against the hemi. Chrysler fans want to forget about this, but it's true! It's a tribute to his driving skill and the machinery too. When the 427 Ford was developed further into the tunnelport version, it remained a competitive tool, but the basic 1958 design was finally replaced with the BOSS 429 “semi hemi” and that motor was able to battle Chrysler to a more than an equal draw before big block racing became a thing of the past. If you ever watch those classic NASCAR races with David Pearson, Richard Petty, Cale Yarborough, etc., you'll see both brands on the tracks passing each other almost at will. It was very competitive. Both brands won races too, during the years of '63, '64, and '65, Ford literally swept the tracks clean with the FE.
My point for the short history comments about Chrysler, was just to make a point about how good the basic Ford wedge design was, and also how competitive those years were, with Chrysler being the real big block competition of the day for Ford.
On the high rise setup, Ford found the taller intake (and taller head design) allowed fuel to practically drop vertically into the motor and this showed up in higher racing horsepower. This tall design caused hood bubbles because it was so bulky. The Fairlane Thunderbolt, with it’s distinctive hood bulge, is one such example of a real fire breathing high rise setup. The high rise setup required a special high rise head and a special high rise intake to be used together, and it is not possible to use a low riser intake with these big ported heads because the intakes just don’t match up. The high riser was primarily a racing product, and I am not sure it was ever offered for the street (other than a special order from Ford, motor only, or perhaps in a purpose built drag racing car like the Thunderbolt).
Later, Ford developed a high performance low rise and medium rise head, and with some clever engineering those turned out to perform almost as well as the taller one for street use. Our boats have the low rise setup, and it’s not a race-track design. Since virtually ANY head and intake bolted to a 427 motor is to be considered a “performance” part by nature, everything is relative. They do make aftermarket low rise intakes that flow better than our boat intake manifolds do, but since we are only spinning at 4000 rpm, it really doesn’t matter all that much. Edelbrock, Shelby, Blue Thunder, and Dove are some companies making great aftermarket intakes for this motor today. If you look at the torque ratings of high performance 427 motors that produce in excess of 400 hp, you will see our detuned boat motors STILL have enormous torque numbers at 438 footpounds at 2900 rpm. That is an indication of massive torque even from a 300-hp marine version of this motor. The good Ford cylinder heads do their part in making this possible.
If you have the time and want to read a really good article, check out the following PDF file. It has a nice write-up about the FE engine design and some of the features. Keep in mind, that Ford Motor Company poured untold millions of dollars into the development of this motor in order to get all those competitive advantages. It’s in the record books now, and those of us who have these motors in our boats need to really APPRECIATE what we have. They are historic icons, and they are still very strong performers that are built better than just about anything you will find with new paint these days. I dare say, some of those new highly marketed motors would not be running today, 40 years later, if they were put into service at the same time a race-proven solid lifter 427 was.
Our blocks are essentially “the same” as the blocks that were raced in NASCAR. They are the royalty of the big block musclecar era. The cranks in our boat motors are generally the very fine Ford cast iron crankshaft, capable of well over a hundred more horsepower than we have. The heads are very fine, but they are “generic” FE heads found on cars like Thunderbirds and big Galaxies of the day. The intakes are also pretty generic, if you can call a FE intake generic these days !!
If your motors had the high rise setup, your heads would be taller than the ones in your boat, and the intakes would be too. The result on some boats smaller than the 38 Commander, would be a clearance problem. The 38 has the clearance for a high riser, but the smaller boats (and most cars) don’t. Thus, the hood bulge they had to add for those hot race cars that used this setup.
Here is a link to that PDF file I mentioned. Enjoy the read, it’s well written and pretty accurate, but it takes a while to load the file.
http://www.legendaryfordmagazine.com/PDF/2004-08-featuredpowerplant.pdf
The horsepower figures listed are those published by Ford Motor Company. It is generally understood that the high performance 427 motors were actually putting out power ratings in the 450-hp range, and the 428 Super Cobra Jet listing (for instance) at 335-hp is a joke, with a low published rating to get around insurance regulations. It stands to reason, that a smaller 390 with the same compression ratio and a listing of 401-hp a few years earlier, would indicate a Super Cobra Jet high performance 428 with the same compression ratio and larger displacement would have a lot more power than the published 335. Guess what? It did J Therefore, look at some of the power ratings with a bit of a wink, because it was a sign of the times, and not finite reality. That engine was putting out somewhere in the 400-hp range, proven by dyno testing and real world performance hauling lots of iron around on the streets and drag strips.
The benefit we boaters have today, is the benefit of the untold millions Ford spend developing this engine series, and the fact that we have detuned versions that not only perform well, they are so well built they will last almost forever if given good care. The blocks are the same as those raced. The intakes are not racing intakes, but they are still good for their intended purpose. The compression ratios are lower for marine use, and the crankshafts are cast iron instead of the forged steel used to obtain 7000 on the NASCAR tracks. The basic motor is the same, but in a marine configuration intended to provide long service. Those cylinder heads are very similar to those used to produce 400+ horsepower, and with a hot cam and higher compression, our boat motors could produce lots more power, and this is one reason the Cobra kit car builders still seek these motors.
Therefore, anyone running a 427 marine motor today, is actually a part of the Ford racing legacy of the 1960s, part of the NASCAR legacy, and also part of the 24-hours of LeMans legacy too. This knowledge and appreciation for history and good machinery is a big part of the enjoyment I get owning these motors in my Chris Craft Commander. I know this is more than you wanted to hear when you asked about the cylinder heads and the low and high riser versions, but hey, this is a big part of the reason I own the particular Commander I do, and a big part of the fun for me.
Next time you twist the key and hear yours fire up, I hope you have a little more appreciation and fun too !
Regards, all the best (there are no dumb questions)
Paul