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New cylinder heads

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Roughly 15,000 100's were made. I assume the head would also fit Atlantics and perhaps other models as well. In any case, given the relatively small number of engines produced and cars remaining in operation it is an interesting commentary upon the durability of the iron head--or lack thereof--that three or four suppliers have each gone to the trouble and expense of designing, tooling up for and producing a proprietary replacement head. Certainly it is an expensive adventure and the heads are high-$$ items, yet each producer obvioously plans to make money on the venture....
 
Michael Oritt said:
Roughly 15,000 100's were made. I assume the head would also fit Atlantics and perhaps other models as well. In any case, given the relatively small number of engines produced and cars remaining in operation it is an interesting commentary upon the durability of the iron head--or lack thereof--that three or four suppliers have each gone to the trouble and expense of designing, tooling up for and producing a proprietary replacement head. Certainly it is an expensive adventure and the heads are high-$$ items, yet each producer obvioously plans to make money on the venture....
Click to expand...
It is not a comment on the durability of the original iron head 4-cylinder 100, it is a plain fact. The old joke it that there are only two kinds of 4-cylinder 100 Heads, those that are cracked and those that have not been checked. Not sure if it was the quality of the materials, casting process, design or some combination of all of the above, but an original cast iron head that is uncracked is a true unicorn. Hence the demand for a replacement. As to the original question of why would you want a CI head when Aluminum is available, I can't give a rational answer other than originality, although even that seems odd for a replacement part.

Dan M.
 
I recall reading that some vintage racing organizations require the heads be of the original material. Other than that, ....
 
Wow ... the dyno results are impressive--6-cyl numbers on 4-cyl engines. I see some 'tabs' sticking out of the gasket around the number plate, where they often leak. Anybody know the story?
 
Perhaps I should not have pulled my punch, and clearly these suppliers are looking into the future and seeing a viable market in the heads that have either not yet cracked or been crack-tested. It is simply surprising the number of sellers given the relatively limited number of potential purchasers, but as the value of 100's goes up the likelihood that someone will spring for an alloy head no doubt increases.

I replaced my iron head with a DW AL "fast-road" head in 2001 when I blew a head gasket as a result of the erosion of the bridge between cylinders 1 and 2, probably the result of pre-ignition or bad casting or both.

As to why AH Spares offers to sell an iron head I believe John is correct and the organizations with which I race prohibit alloy heads in place of stock iron ones.
I don't know what the rules are for UK/EU clubs where Healeys are way more actively raced than in the USA.
 
Every once in a while I remind myself how lucky we are to have suppliers like DWM, AHSpares, etc. along with great mechanics and advisors like Tom M, David N, etc. We are truly blessed.

On the latest episode of 'Wheeler Dealers' they fixed and flipped a J-H. Mike went back to England to get some parts, and visited a large shop where they were making body panels for several LBCs (probably dropped in on his wife too, methinks). I thought maybe it was DWM, but they had the logos blurred out--why???--and I don't think DWM does body panels for J-Hs.
 
Interesting development. Cast iron heads had become so rare that UK competition rules were amended to allow alloy heads, as racers complained they could not find any iron replacements. I think this also applied in FIA sanctioned events.

The graph shows a pretty aggressive peak power number of about 150bhp which is about what the top 100 race engines are producing over here. You will not get that simply by bolting this new head on to your standard car.
 
About the only advantage that aluminum heads have over iron is heat dissipation. Admitably that is a BIG advantage when considering compression ratio, timing flexibility and overall performance. But iron heads have their own set of advantages as well: 1. material stability there-by reducing head gasket problems. 2. no adverse reactions to anti-freeze engine coolants. 3. Generally longer life especially in normal non-competitive, street driving. If you have aluminum heads you should check the bolt torque reqularly and at least change your anti-freeze more often. I believe the three biggest reasons that manufacturers will produce the aluminum heads is because 1. they are cheaper to produce, 2. the market wants them (oh god ya gotta have an aluminum head), 3. The sanctioning bodies allow them. One last commentary, I had a new engine built a few years ago ,by a professional race engine builder, for my '70 Vette. It is a roller cam, roller rocker, 383 cu in stroker small block. It dyno'd at 467 hp. I specified Iron Eagle 180 Iron Heads. I specified the 180 runners verses the larger sets because of the theory of velocity over volume. I specified the Iron heads because I told the builder that even though I want high power that since this was strictly a street driven car I want to never touch this engine again after I install it in the car. Long term durability that's why I use Iron.
 
Vette, aluminium heads are considerably lighter and removing all that weight from high up in the front improves handling.
Racers won’t want to switch back to iron unless forced to.

I don’t understand those torque and power curves as they don’t cross at 5252rpm.
 
DerekJ said:
...
The graph shows a pretty aggressive peak power number of about 150bhp which is about what the top 100 race engines are producing over here. You will not get that simply by bolting this new head on to your standard car.
Click to expand...

So, you're disputing AHS's claims?

"Significant BHP and Torque power gains when tested on our development engine using H4 carburettors and all standard engine components including the O.E. cast iron exhaust manifold and a slightly higher compression ratio. "
 
Derek, I agree with you. Those are all good reasons for using them in racing applications.
 
Bob_Spidell said:
Wow ... the dyno results are impressive--6-cyl numbers on 4-cyl engines. I see some 'tabs' sticking out of the gasket around the number plate, where they often leak. Anybody know the story?
Click to expand...
Bob, those tabs are the telltale sign of a MLS-type head gasket
being used. There will usually be two tabs on each side where the multiple layers are riveted together.
 
DerekJ said:
The graph shows a pretty aggressive peak power number of about 150bhp which is about what the top 100 race engines are producing over here. You will not get that simply by bolting this new head on to your standard car.
Click to expand...

Derek, 150 is the torque not the HP. HP numbers are on the left side of the graph and in this case it is 111 HP.

The use of dual graph graduations will also explain why the curves do not cross at 5252 rpm. Even if they used a single shared graduation, the curves would not cross as they only go to 4500 RPM.
 
Thanks Craig,

Apologies all round for my inability to read a graph properly!����

That explains both my queries, so Bob I’m no longer disputing the numbers.��

edit..seems like my keyboard emojis don’t work and I get question marks instead!
 
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