1946-1949 1947 346 camshaft the same used in the tank motors ?

[Flying Finn]

Dose anyone know if the 46 - 47 cars with the 346 use the same camshaft as used in the tank motors ?

[Brad Ipsen CLC #737]

Parts book shows same part number from 36 to 48 for cam so I would think military engine would be the same also.  There would be no reason to make them different.  The tach drive was in the distributor tower so that would not cause a change.  I have taken apart a military engine and did not notice any difference also.

[Flying Finn]

Thank you for your reply.
Jaan

[Warren Rauch #4286]

  Cadillac really didn't want people using the surplus parts.They sent a 1945 general service letter telling them so.That must not have stopped much,because in 1947 they sent one explaining why.

From Cadillac General Service Letter# 563 March 13,1947 Summary of engine section

ENGINE:

 Engine Accessories   Electric units different voltage (starter ,generator,dist,coil,etc)
                      Early units different crankcase ventilating system

 some types of blocks and bell housings machined for military parts

 Pistons and rings special for military use

Crank and flywheel balanced different

Oil pump equipped with military adapter

manifolds military only

oil pan deeper on military engine

water pump inlet and outlet different positions

Cylinder heads water outlets moved and water passages inside varied

In addition, many other unit assemblies  which will physically fit are not interchangeable ,because of internal differences such as Carburetor calibration.
.

They also warn that parts for the military engines and transmissions are not available ,because Cadillac had to turn over all manuals,parts,etc to the Ordnance Department.

Well at least they don't mention Camshafts.

Warren

[Flying Finn]

Thanks Warren for all that information.
I found on EBay a nos camshaft and Egge Machine has a reground original in stock.
The nos is $300 plus shipping and Egge Machine is only $150 plus shipping .. its not about the price difference , I just want the best for my 47 and in the past I have seen some issues with regrinds. But I am sure if Egge is supplying it ,, will be fine .
Thanks, Jaan

[tcom2027]

Interesting topic.

Only thing I can think of is a slightly different grind to alter the power band and increase torque in the milspec engines. Think RV cams in pick ups back in the day.  It wouldn't take new tooling to accomplish this, just a different set up for the grinders.

Also it may have been changed to compensate for the increased weight of the cast iron pistons used in the milspec engines.

Me, I'd install it. You may get even more torque from an already stump pulling engine. Easy for me to say however, as I'm not the guy who has to change it out if it doesn't work out. Not quite as easy as swapping plugs on the right bank.

tony 

[harry s]

Warren, That is very interesting information as this question comes up time to time. I had a NOS surplus cam that went into a friend's rebuild. We compared it with an original and could not find any differences. He has not had any problems. The packaging of the cam was typical govt. It was packed in a fairly thin black grease then wrapped in foil which was then wrapped a cosmoline mesh, then a heavy paper and finally boxed. Terrill Machine used to sell surplus lifters that were packaged in cosmoline then encased in a wax shell and boxed. Unpacking and cleaning added a few hours to the job.   Harry

[KenZ]

Regarding Warren's post does anyone know what was the difference between the pistons and rings special for military use engines vs civilian?   I am just curious as I have a tank engine installed in my car.  Was pretty much aware of most of the other differences.  Thanks Ken Z     

[tcom2027]

The milspec engines had cast iron pistons and cast iron rings. They are hevv---ey,

Makes sense as aluminum and chrome were essential for aircraft and artillery production.

In the late eighties I had a chance to see an early Chaffee engine disassembled for rebuild. It was in Yuba City California where the surplus engines were used extensively after the war in bank out buggies used during the rice harvest in the Sacramento Valley. THey were were worked very hard and held up.

Do your heads have the firing order cast in them at bottom and "Cadillac Motor" in a crescent at the top? IIRC that pattern is from the Chaffees. I believe there were several patterns on the milspec heads. One,"Cadillac Motors" along a boss in the center of the head is another I have seen.

I assume you swapped out the angled intake manifold for the civilian manifold?

I'm sure some more much more conversant in the military engines and transmissions will have much more specific information than I have provided.

tony

[KenZ]

Tony,
Didn't even think about the pistion/rings being different prior to this topic. The heads on my tank engine are from a 1938 Lasalle Engine or so I was told by my father. I was able to utilize all the original 1936 accessories and attaching hardware EXCEPT the flywheel, oil pan and distributor.  Engine runs excellent as configured.  Thanks for the info,  Ken Z   

[Brad Ipsen CLC #737]

A couple of stories on the tank engine I disassembled.  It came out of a house that was being sold but there were car parts in it that needed to be disposed of.  They had been in the house since the 50's. It had been modified to go into a 41 Cad, it least there were other 41 parts there.  It still had the heads labeled "Cadillac".  My first mistake was I threw these away because I thought no one would want them.  I had normal heads to replace them.  Later I found at least at the time these were in demand at a high price.  It did not have cast iron pistons so at least some of them had aluminum pistons.  The engine was in near new condition.  It had not been run much in a car.  One thing I really wanted out of it was what I thought was going to be a brand-new brass cam gear.  It was almost completely worn despite the rest of the engine being like new.  The good part, it led to the correct diagnosis of why these brass gears fail.  When converting a tank engine to a car engine the tank distributor tower would be removed and replaced with the car one from the old engine.  The military one is different.  The problem is most of these were wore out due to the oil hole being plugged resulting in bushing wear.  The distributor tower gear is the hardest gear in the system, and it becomes a cutter of the brass gear due to the slop in the tower bushings.   

[tcom2027]

Hi Brad,

The engine with the alloy pistons may have been late war production. early to mid'45. By then government contracts were being cancelled or severely curtailed and production facilities were beginning to be converted for the production of consumer products, Metals, previously designated for war production were being freed up.

The 346s were used in many applications, various tanks, recon vehicles and gun carriers. Within the tank groups there were differences between the units used by the US and the units sent to our allies, the Brits, for example. Even within these groups there were constant iterations resulting in changes mid production. Eighty years later it is difficult to make a definitive statement about a specific part of a specific engine.

I remember years ago when I was at at a show and saw a '41 with CADILLAC MOTOR heads. I commented to the owner about having tank heads on the engine. He seem ed crestfallen. By his body language I realized he didn't want any more information. And so it goes. 

When overhauling my '41 engine I had a silicone bronze gear made. It ran over 4K miles with no problems, but hardly a test. I have a rebuilt '38 LaSalle engine here that is waiting to go into my '39 that has a silicone bronze gear in it. I have no doubt it will last as long as I will. Which begs the question, with the advent of high strength, heat resistant polymer plastics why not a 3D printed gear. Will the engine be running 8900 rpm along the back straight at Talladega or towing a 31' Airstream trailer? Probably not. I'm sure brass, navy brass, silicone bronze, or bronze gears will be adequate for hobbyist applications.     

There are a lot of factors that lead to the failure of the gear, worn bushings, possible slightly bent distributor shaft, wear in the oil pump causing binding of the gears. Oil pump gears mismatched with the housings, Even excessive oil pressure can contribute. Unlike Chrysler which depended on high pressure, lower volume, in their engines. GM favored low pressure high volume lubricating systems. Cadillac spece'd 30psi. Each system has its advantages and disadvantages. It's been my experience that the manufacturer of a product knows a lot about the product they manufacture. Will shimming the relief valve and using 40wt oil kill the gear, probably not, but it may induce a little extra wear on the gear.

That's all I have.

tony