Since the mid-1990's when I was upgrading my various Model A's for cross-county driving from Arizona to Iowa and back on vacations, I experimented with several different higher compression cylinder heads. By achieving more horsepower mostly through cylinder head upgrades and secondarily through carburetion improvements, I was able to whittle the 1450 mile trip down from 2 1/2 days to just over one day (27 hours), driving straight through, stopping only for gas and the call of nature. Without a better cylinder head than the original one, this significant time reduction would not have been possible. Because I did not stop to sleep during the trip, it was imperative that I reach my goal (on a limited vacation schedule from work) as soon as possible before dozing off at the wheel.
I made this trip numerous times over the period of 31 years (1973-2004), almost every trip with a different cylinder head for comparison, sometimes more with the same head. So, I think I can speak from practical experience about what worked best for me in terms of cylinder heads. Camshafts, carburetion, valve size and gearing tested could fill another thread some other time.
The heads I tested included a milled stock Model "A" head, the 1932-34 Model "B" head, the 1931 Model A Police head, Brumfield's standard 5.9 head, an aluminum Thomas head, both the 5.5 and 6.0 Snyder's heads, the 7:1 CR Super Brumfield head and the Riley Two-Port 7:1 CR repo OHV head. All had their pluses and all had their minuses, ranging from cost to expected improvement and reliability.
Predictably, the most disappointing of the bunch were the milled Model "A" and Model "B" heads. There was no improvement felt at all with the milled Model A head. Maybe the dyno would show an improvement, but I am talking about FEELING the difference on the road, which is really all that matters, isn't it?
Using the Model "B" head (with the "C" embossed on it) with only a mild increase in compression and no major combustion chamber improvement, not much gain was experienced for the money spent on acquiring the head, a new head gasket and rebuilding the special three-bolt hole water pump, which always seemed to fail. I would recommend neither a milled "A" or Model "B" head for sustained long distance driving, if one wants to experience noticeable increased performance.
At the other end of the spectrum were the Super Brumfield and Riley Two-Port heads. These were far superior to the other cylinder heads I had driven. It's probably not really fair to compare an OHV conversion to a flathead because of the difference in breathing capabilities. Our Model A engines are just big air pumps: the more air you can force into the cylinders and then force back out, the more power you'll make. An OHV has a distinct advantage over a flathead in this regard and should outperform a flathead of the same compression ratio, which my two heads were. On my trips using both heads, the same downdraft carb, headers, Aires muffler, similar camshaft grind profiles and a Mitchell overdrive leveled the playing field. In other words, the cylinder heads were the only major difference. The Riley probably made more raw horsepower, but contrary to all expectations, I would say it was almost a draw between the two in terms of performance on the road. There were many steep mountains to climb in northern Arizona and in central New Mexico, and both heads performed brilliantly in pulling power, very rarely needing to go back down to second gear, even on the steepest mountains. Acceleration when needed to pass trucks at 65 MPH on level interstate highways was instantly on tap with both heads. Miles per gallon were roughly similar. In short, the R2P OHV was not a clear winner over the Super Brumfield head in any facet of driving. For the money difference (roughly $400 versus $2750 in the late 1990's), the Super Brumfield was the better way to go, exotic though the R2P is, looking like a million dollars with its polished dome valve covers. I still drive the Super Brumfield head year-round without ever having suffered a single blown head gasket, whereas I went through five using the R2P in the first two months, finally buying an expensive solid copper gasket, which held. Guess which one of these heads I consider more reliable, let alone the better bang for the buck!?
I am not rebutting what others have written here so far about their experiences or preferences in terms of cylinder heads, nor would I expect them to rebutt what I have experienced. We know what we know from experience. My point in making this long post is that one must be careful not to lump comments about Brumfield heads into a single one-size-fits-all category because there were TWO Brumfield heads that should be considered. Of course, most guys opted for the less expensive Standard Brumfield, which is where most comments originate, from among those owners. To say "the Brumfield head did this or that" on dyno without specifying that it's the Standard 5.9 Brumfield being cited is unfair. To make such statements more complete and accurate, it should be stated that the STANDARD Brumfield head was tested and that a Super Brumfield would have undoubtedly resulted in higher HP and torque figures. Nice as the Standard Brumfield is, it is easily surpassed by the Super Brumfield in my opinion. It may be a moot point now to make a distinction between the Snyder's heads and the Standard Brumfield, since neither the Standard nor the Super Brumfield head is being manufactured for sale anymore. But there are plenty of them out there in Userland that when one becomes available new or used, it is quickly snapped up. Doesn't that tell us something about their desirability right there?
If the argument comes down to which head is better - the Snyder's 5.5/6.0 flavors or the Brumfield Standard - I still feel the Brumfield gives a better boost (torque) in third gear than either of the Snyder's heads. That place in the power curve is the weakest in Model A's and the reason we hold up traffic behind us until speed has increased in high gear. The Brumfield Standard head was and is the clearly superior in this area alone. Once again, however, unless the Standard Brumfield head goes back into production again, this discussion is purely academic. We are now left with only the two Snyder's heads, which I do feel are a big improvement over the stock Model "A" and "B" heads. But if push came to shove and one of these were lying next to a Standard Brumfield head for sale, I'd pick the Brumfield every time. And, no - I am not a salesman for the Brumfield Company, nor have I ever met Larry Brumfield personally. I just believe in endorsing a good product when I find one for the benefit of others.
Marshall
