Here's a quick recap of the the 194 head/open chamber head debate as some are kinda' fuzzy on the details, some guys are new to the forum and having difficulty finding the threads regarding it, and some are just confused as has been said by several.
A few years back, just over 200 dyno pulls were made with both a 292(first engine tested) and then a 250(also tested with a turbo and even side draft carbs). A large selection of cams, intakes and carbs, cylinder heads and headers were prepped and swapped to see how each combo of these components enhanced or not with other components. Starting with a baseline 292 stock engine, each test involved many possible combos of all the components already mentioned. The cylinder heads were available from stock size valves, unported stock castings all the way up to big valve(1.94"), lump ported. A variety of heads were also prepped that were everything in between. This variety also included both the traditional late model heads in the open chamber configuration, as well as the early 194 closed chamber heads. All cylinder head comparisons and swaps were made in conjunction with other cam and intake swaps as well, over 120 dyno tests were performed with the 292 engine alone. So you can imagine all the different combos of different components that were tested and evaluated. However, when it came to the cylinder head swaps, thats where some seem to get confused on what was said, what was tested, how the heads that were tested were compared, and how the heads were prepared and modified.
Starting with the heads, as I stated before, they ranged from stock valve size, unported to big valve, lump ported castings, both in the open and closed chamber variety. When it came time to swap between the open and closed chamber stlye heads, they were only compared on a basis as to how they were comparable to their open chamber equivalent in valve size, lump ported or not lump ported, etc....keeping all comparisons equal except for one has open chamber and the other closed chamber. All the machine work on the two seperate styles of heads were performed at the same time, the two styles of heads were given the same machine work procedures with no advantage given to either one so the only true difference between the open and closed chamber heads for any test comparison was the advantage that GM gave them originally, and that was the difference in the stock combustion chamber sizes.
The engine testing was helped in part by over 75 Inliners board members. All gave input as to what they wanted to see tested, and came up with a set of parameters that were to be followed. The first parameter was the engine must have 9:1 compression, that worked out good, because with the open chamber head the 292 had 8.8:1, and the closed chamber head yielded 9.25:1. The other parameters were the cams to be tested as well as intakes and carb combos.
Ok, back to the heads. Why has this become such a point of confusion. Some how the results has been twisted into being said that the closed chamber head is no good, it is worthless and a boat anchor, Elvis is still alive and in Florida....just kidding, but you see how it has escalated into such untruths.
Fact #1, the closed and open chamber heads recieved the exact same machine work and prep for each pair of heads tested. No trick modifications were done or elaborate "black bag" of goodies pulled out and done to one head and not the other. Both heads of each style had no advantage to the other besides what GM gave them originally, and again, that was the stock chamber size. Only one half of one compression point was the only difference between any head compared at any time. They each had the same valve size, same valve job, same valve part#, same everything....that was the only difference between any head casting tested and tested on a one-to-one basis for every dollar spent on one, the same dollar was spent on the other, neither given any advantage over the other.
Fact #2, Out of all the comparison tests performed involving the cylinder heads, the 194 casting closed chamber head never produced more power or torque than its comparably prepped open chamber head. It never made the same power or torque as its comparably prepped open chamber head. It only produced less power and torque than its comparably prepped open chamber head.
Fact#3, Its was always said and concluded that with additional machine work or modifications, the 194 head could have potential above what was seen in these tests. Hank without even knowing he did so, proved this point by his modifications to his own 194 head by milling it an additional .060" beyond what our test heads were prepped with. By doing so, he accomplished a compression ratio of 12:1, which is 3 compression points beyond the parameters set for our testing, but still shows and proves that the 194 can have potential if further effort and additional money are put into it. But working within the parameters set for our testing, it did not show that. So if it was said the 194 head was not a worthy swap, it was only meant within the context of our testing where the 194 head only had one half of one compression point advantage over the open chamber head.
Fact #4, 99% of anyone that is going to build a 250 or 292 for the street is only going to build and prep it for easy street driving and doing only the absolute minimum and basic in machining to do so. And when doing that, especially to a 194 head, you will never see or experience the gains Hank saw with his 194 head!
