Engine: Aluminum Inline 8 cylinder head for 1932 to 37 ??

[VintageRaceCar]

Trying to find out which year, model and engine size had a factory Aluminum Cylinder Head on an Inline 8 engine ?
I believe I have seen a 1937 Sedan with the 250 cid inline 8 engine, which had a factory aluminum head ? Can that be correct ?
Did Studebaker ever make an aluminum head for the larger 337 cid inline 8 engine ?
Thanks in advance,

Mike

[garyash]

The 250 cubic inch straight 8 engines from 1934-37 had aluminum heads available. These were used in both Commanders (1934-35) and Presidents. The later engines used part number 186189. There were no production aluminum heads for the 1928-33 big 337 cu in engine.

Here are two of the 250 cu in engines. The one in front has a cast iron head, the rear one has the 186189 aluminum head.

[jclary]

Here's a question for you engineering types...As regard to the expansion rates of dissimilar metals? How does it figure into the design of mating aluminum heads to cast iron engine blocks? Water passages, casting thickness, torque specs, etc.? Are there "alloy" and special "heat treat" specs required to minimize having a wide disparity in how the two materials expand and contract?

Just curious.

[garyash]

[PackardV8]

Gary, .019" differential is not critical when spread along a 30" span. The problems with aluminum heads and iron blocks were more a result of there being no good antifreeze/coolants to prevent dissimilar metal corrosion.

JackVines

[garyash]

Jack must be right because we know it works - most of the time. But, I still wondered how it works if the head doesn't slip on the gasket. Here's a rough guess of what happens:

The head is 7.5" wide and about 2" high. It's mostly hollow for cooling water with a wall thickness of about 1/4" for both the iron and aluminum heads. In some cross-sections where there aren't spark plug holes with thick bosses, etc., the cross-sectional area is 4.5 sq in. Other places it's more, but let's take 5 sq in as an average. We can stretch the head by pulling on the ends or compress it by squeezing on it. In this case, we want to keep it from growing longer as it heats up by squeezing on it.

The 28 studs, 1/2-13 in size, are torqued to about 50 ft-lbs. This is the maximum for a Grade 2 bolt, but old head bolts are closer to Grade 5, so we're not loading them very much because we don't want to dent the aluminum under the washers. Even so, this will produce a clamping force of about 5840 lbs on each stud for dry threads, or a total of 28 x 5840 =163,520 lbs. We'll assume a coefficient of friction of about 1, hence the head won't slide anywhere. In order to compress the 30" long aluminum head by about .020", the force required is F = d * A * Y / L where compression d=.020", area A = 5 sq in, L = 30", and Young's modulus for aluminum Y = 10,000,000 lb/in². This gives the required force F = 33,300 lb or 1190 lb per stud. Since the clamping forces are very much higher, the head can't grow much in length (relative to the cast iron block) even as it gets hot. Maybe the block actually gets stretched a little bit while holding the head in place because the iron is stiffer than the aluminum by a factor of about 3.

The same effect happens in the sideways dimension, but since the width is 1/4 of the length of the head, the additional forces are lower and we still have plenty of clamping force.

This guess may not be exactly right, but it indicates why the aluminum head should seal to the iron block if we tighten the studs correctly and keep them tight. As my high school physics teacher used to say after showing the solutions to problems that we students didn't get right, "Gosh, physics is fun!"

P.S.: We don't have specs for the torque on studs or head bolts (or any other bolts) on pre-war cars because the commercially-available torque wrench wasn't developed until 1938.

[Tom Bredehoft]

We don't have specs for the torque on studs or head bolts (or any other bolts) on pre-war cars because the commercially-available torque wrench wasn't developed until 1938.

Amazing, they were good enough mechanics they could torque them correctly (or near enough). Talk about seat of the pants mechanics!

[PackardV8]

We don't have specs for the torque on studs or head bolts (or any other bolts) on pre-war cars because the commercially-available torque wrench wasn't developed until 1938.

Amazing, they were good enough mechanics they could torque them correctly (or near enough). Talk about seat of the pants mechanics!

The feel is easy. What's hard is doing it all day long every day. "The muscles in his brawny arms stood out like iron bands."

The local rebuilder just spent $250,000 for an automatic torque machine because nobody wanted that work station.

Jack Vines

[t walgamuth]

I believe it would be true to say there is movement and slippage on an aluminum head.

I know that on an eighties Mercedes diesel head on the turbocharged engines you tend to get head gasket failure around 275,000 miles due to the higher combustion temperatures than the non turbo engines (which might last 500,000 plus on the original head gasket).

When taking the head off a turbo engine the block and head both tend to need surfacing to remove the worn place. Also the blocks on those engines will be twisted slightly from the torque and will require surfacing to true the surface of the block with the crank, then when boring the bores will be made truly perpendicular to the crank again as well.

None of this is a lot but it is measureable....perhaps half or a third the thickness of a business card.

It is pretty amazing!

[nvonada]

There definitely is movement. Even if the head and block are the same material the gasket certainly is not. But the total motion is not all that much and it all works out most of the time. Back in my water-cooled VW days a head gasket leak almost always meant either a mechanic had screwed up or the head was warped.

[VintageRaceCar]

Thanks so much for your response Gary.
In the picture you posted it looks like the Aluminum head on the engine in the background, is quite a bit smaller in height (front area).
Were all Aluminum heads built that way, or did they make some which look like the Cast Iron head ? Looks like the Aluminum head would hold quite a bit less coolant. (sure it dissipates the heat better) How about the combustion chambers ? Is there much difference in the compression ratio between the Aluminum and the Cast Iron head ?
Looked on Egge Machine's website and they specify, that their head gasket will only fit the Cast Iron head. They don't have one available for the Aluminum head. Are they that much different ?
Thanks again,
Mike

[garyash]

Mike, I think all of the aluminum heads looked that way with a raised rib down the middle, not like the flatter cast iron ones. The aluminum head was standard on all President models 1935-37, iron heads only on the earlier and later cars. The compression ratio is 6.5:1. Remember that gas of the period was only 75-80 octane for regular, no more than 87 for "high test". While the water volume capacity in the aluminum head may be less than the iron heads, the water flow is the same, as set by the water pump, so there is plenty of cooling for the head. Stock output was 115 hp at 3600 rpm. With the right cam and enough carburetion, the 250 cu in engine should put out 180-200 hp at 4000-4400 rpm. What would be really slick would be to mount a Graham-style centrifugal supercharger from the period. Even 1 or 2 psi of boost would be enough to really wake up a flat head engine.

The aluminum heads weighs 17 lbs versus about 50 lbs for the iron head.

The correct copper/asbestos gasket, p/n 184631, is available from Sandy Olson at www.olsonsgaskets.com. He can supply complete gasket sets. Note also that the aluminum heads used 1/2-13 studs with necked-down sections to accommodate the vertical expansion of the heads when hot.

[VintageRaceCar]

Gary,
Thanks once again for your response. Lots of great info and I actually looked on Olson's website, but thought he would not have the correct head gasket, since he had not pictured it on his "Our Products" page. Never noticed, that he mentions "New Production Copper Head Gaskets" above the pictures. Guess he just did not have a picture of the Studebaker gasket posted.

Regarding the Aluminum cylinder head. Could not find a picture of the head I was thinking of and could not remember, where I've seen it. The Aluminum head I was thinking of was pictured in a photo on this site. Was during a thread called "1930s Studebaker racing engine photos I found".
Here is the picture:



The Aluminum cylinder head in these photos has the raised center rib, to elevate the water outlet neck, like the picture of your Aluminum
head, but it is quite a bit thicker and looks to be about the same size as the Cast Iron head. Ever seen a head like this in person ?

Yes, putting a Graham Supercharger on the side of one of these engines would be awesome. Putting a Supercharger on a Flathead engine will definitely wake them up. I have tried that myself. Ran a car out here in California at several El Mirage Dry Lakes events, with a Flathead V8 and a 6:71 blower. They really wake up if you do that, right before they go away and you are coasting through the finish line.
Mike

[garyash]

Those photos you posted are of one of the Indy racing engines that Studebaker was developing for the 1934 race. However, due to the company going into receivership, the racing program was cancelled and the engines were sold off at $750 each. At least one of those wound up in a Studebaker standard car, 4-carb set-up, magneto, and all. The planar suspension shown in the photo you posted makes it a 1935 or later car. I think I recall that the car went to England, but my brain is fuzzy on this one. I'd love to know what happened to it.

There were some other aluminum heads used in 1934 and early 1935 Dictators and Presidents with 250 cu in engines, both standard and high compression. I see six other part numbers in the 1929-40 chassis parts catalog to cover these, but I've never seen one "live". Maybe someone else has one of these heads and can post a photo and info. The part numbers are: 182013, 183404, 18440, 186615, 186197, and 186615. These should be the same as the casting numbers.

I've got sets of the aluminum 4-carb intakes, linkages, modified carb throttle shafts, and brackets available for 250 cu in engines, if you want some and need to empty your bank account of too much spare cash. Then all you need is four identical Stromberg EX-23 carbs to mount on top.

[Hallabutt]

Gary,

I was enthralled by your explanation, but admit that you lost me about half way through it! No need to try the clarify it for me, it would just give me a headache!

There were at least two different manufactures that cast these heads for Studebaker, Lionite which is the one most often seen on 1936-37 Presidents, and Bonolite. I have a Bonolite that is in very poor condition. The Bonolite that I have is a much heaver casting then the two Lionite heads that I have, but that didn't stop it from developing about a dozen significant cracks. I don't remember where I got it or do I know what it was originally used on. I keep it around for comparison with the Lionite. It is the only one that I have ever seen. There is another head that a friend has on his 1936 that I think is different then either of the other two, but don't know the manufacturer.

There are a few of us crazies out there that persist in using the original aluminum, but very few. Most sensible restorer/drivers switched over long ago to the less problematic cast iron head, as used from 1938-42 Presidents.