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B engine teardown, and, are cam bearings DIY install?

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01-26-2008 14:36:30

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First, I want to say thanks to the posters on this board. I've learned alot from reading and it's been a great help. I've been tasked with rebuilding an Allis Chalmers B gas tractor that's on my wife's family farm. It's a 1950. The thing ran (although I never really saw it run) and they complained it smoked blue real bad. The final straw was a massive oil leak at the front crank snout. So I broke it down and took the engine home to take it apart. I had to drill and tap the crank pully to pull it off, no prob. All else was easy. I can't see any sign this has ever been apart before. But overall, it looks super; no water damage or rust, and the cam looks great, the crank mains and journals look really nice. There bores are tapered at the top so there's a big ridge. I've decided I'm just going to do a complete rebuild with new sleeves. I just used a 4x4 block (wasn't even oak, it was pine) to smack the liners out. It was easier than I thought it would be. So, I want to send the block to a machine shop to boil it out. Lots of crud. Question: I see the cam and governer bearings are "split". Does this mean they can be installed without a pilot tool? Can I press them in by tapping them in? Or should I have the machine shop do it?


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Gordon in IN

01-28-2008 18:41:42

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 Re: B engine teardown, and, are cam bearings DIY install? in reply to Squidtone, 01-26-2008 14:36:30  
Hi Dave,

Just thought of some more "stuff".

If you have the block "boiled out" with the cam bearings installed in it, the process will most likely destroy the cam bearings. Worn cam bearings are one of the causes for lower than normal oil perssure in these engines. Recommend that they be replaced if there any question.

The "split" type bushings usually require a better installation method than the solid type in my opinion. If the cost for the "shop" to install the cam bearings/bushings is not too high, that is probably the best way to go. Check the cam journals for wear. The bushings were available .002 undersize - at one time (for worn journals).

Are you sure that you want to "boil out" the block? If it is "painted" (a dark reddish brown color) inside the block, I would NOT recommend "boiling it out" as it will remove the "paint". This "paint" is a sealer for the cast iron and prevents oil "seeping through" any porosity in the casting. If the engine is original and has never been "boiled out" it is likely that it still has the "paint" inside the block. I would not recommend removing this paint. Just my opinion. Actually the block is fairly easy to clean with a "power washer" or at a "car wash".

Recommend "K&W Copper Coat" head gasket sealer for the head gasket if it is the metal type. Also recommend the metal type (rather than the fiber type) head gasket, if you can get it.

You might want to "glue" the valve cover gasket to the valve cover and "grease" the gasket surface next to the cylinder head (with a good high temperature grease). You will likely have the valve cover "off and on" a few times if you follow the cylinder head bolt re-torquing and valve clearance adjusting recommendations in the manual. (The manual recommendations will likely prevent a blown head gasket, if followed)

Again, the Manual is very helpfull.

Good luck, Gordon in IN

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01-28-2008 20:15:59

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 Re: B engine teardown, and, are cam bearings DIY install? in reply to Gordon in IN, 01-28-2008 18:41:42  
Gordon in IN,
Thanks! Wow, lots to think about. I haven't taken the head apart yet. I just bought a valve spring compresser, so I hope to use it and take apart the head in the next couple of days (busy with normal work dagnabbit) Superficially, it looks good, but I wonder about excessive valve stem clearance.

I'll check for brown paint inside the block, but I saw no sign of paint. However, since there don't seem to be many oil galleries (compared to an auto engine) I may just try to power wash this thing if it gets warm enough outside! A local machine shop wants 50 dollars to "hot-tank" it. I asked about eating cam bearings, and they said it won't hurt those. That makes me suspicious on what the cleaning actually entails.

Drilling the crank kinda scares me, especially since it's not really my tractor!

I see rebuild kits have new cam bearings, but they appear to be solid "O"s rather than split "C"s.

I'm going to digest some of this new advice and I hope to post back with an update for those who may be interested in how it turns out.

Thanks again!

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Gordon in IN

01-28-2008 17:50:14

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 Re: B engine teardown, and, are cam bearings DIY install? in reply to Squidtone, 01-26-2008 14:36:30  
Hi Dave,
You may want to consider a high compression overbore (larger bore) piston/cylinder kit for your "B". A piston/cylinder kit gets you new piston pins (with the new pistons) that is a big advantage.

You may want to get a "I & T Shop Service" Manual for your "B" They are very helpful. Most "TSC" Stores have them and I think that they are available from suppliers on this site. There are a lot of "small things" and/or "details" that are different on the AC "B" engines than on most automotive engines.

Be sure you understand the shims on the connecting rod and main bearings that control the "crush" of the shell insert and that you are confident that you know how to install and adjust them. (The I & T Manual explains this very well - para 97, page 21.) Tightening torque values are also important (page 4).

The I & T Manual indicates that the camshaft uses "three renewable split type bushings". (I have seen both split type and solid type replacement bushings used in "WC" engines.)

Be sure to clean all of the "sludge" out of the "hollow" camshaft (that is the "oil gallery" for the engine maim bearings).

Also be sure to clean the hollow rocker arm shaft, the grooved rear rocker arm support stud, and all oil holes in the block and the external oil lines.

Be sure to used the "string wound or fiber packed" oil filter with the removable "stick" in the center. You can also want to fill it with oil and "soak" it in oil before installing it to help bring the oil pressure up quicker.

If you want to "up grade" the engine oiling system you may want to investigate modifying the crankshaft to provide oil to the rod bearings. (Number 1 rod bearing from the front main bearing; Number 2 and 3 rod bearings from the center main bearing; and number 4 rod from the rear main bearing.) This requires "drilling" the crankshaft in four locations. This is like a "CA" crankshaft. If you do this remember to "plug" all of the "rod bearing oiling holes" between the lobes of the camshaft and in the sides of the rod bearings.

Wheather ot not you decide to do the above "upgrade" to the engine oiling system, you may want to increase the diameter of the holes in the center bearing journal of the camshaft. If you think about having the same oil flow area of the holes in the center cam bearing journal as in each of the front and rear cam bearing journal oil holes, it does not seem "right". This means that there is twice as much area for oil to leave the hollow camshaft as there is for oil to enter the camshaft in the original design. This "might" be the reason that the front and rear main bearings usually show more wear than the center main bearing in well worn engines.

If the engine was burning a lot of oil it may need new valve guides and perhaps new valves.

You might need to check and regrind the rocker arm contact areas (where they contact the valve stems).

You can also "pump" oil into the engine through the oil fitting "T" on the side of the block prior to starting the engine. Or you can "spin" the engine with the starter or with a hand crank (with the spark plugs removed) to get full oil pressure before you start the engine the first time after overhaul.

Good luck on whatever you decide to do, Gordon in IN

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01-27-2008 11:44:28

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 Re: B engine teardown, and, are cam bearings DIY install? in reply to Squidtone, 01-26-2008 14:36:30  
Thanks for the replies. That cam bearing removal tool looks good. I don't have access to a lathe, but I do have access to a CNC machine at work. I think I'll try to make a disc like shown. And based on the what DickL said, I'll try to save the governor bearing also.

And yes, I did mark the piston rods and caps, BUT I dropped the box with the organized tappets and they're now mixed up. Rats. I see they can be resurfaced, but I wonder about them matching the "used" cam.

Thanks again


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Dick L

01-27-2008 12:20:54

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 Re: B engine teardown, and, are cam bearings DIY install? in reply to Squidtone, 01-27-2008 11:44:28  
I always toss the tappets and push rods in a box. I check each one for wear before re installing and replace if necessary. I re read your first post and read split cam bearings. I have never seen split cam bearings. If they are split I would replace with new. You could only check the clearance for re use with the bearings installed with the cam installed. This can be done. If you are handy with a set of telescope gages and a set of mic's that is a good way to go. Best clearance being from .001 to .002.

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Dick L

01-27-2008 10:36:59

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 Re: B engine teardown, and, are cam bearings DIY install? in reply to Squidtone, 01-26-2008 14:36:30  
Nice set of pictures. Looking at those pictures I hope you marked the rod and main bearing caps when you removed them. Rod caps are not interchangeable for the most part. The cam and governor bearings need to be removed. I have reused cam bearings that I have removed and checked. The way I check them after they have been removed is to slide them on the cam and check with a feeler gage. If I can slide a .003 gage thru easy I do not reuse them. I made my own cam tools out of brass. This is one below. The bolt is just how I store them. I have a long handle to remove and install cam bearings.

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01-26-2008 14:53:11

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 Re: B engine teardown, and, are cam bearings DIY install? in reply to Squidtone, 01-26-2008 14:36:30  
have installed them using a soft wood block or a large socket with an extension. Sure someone makes a "tool" for this but they drive in easy, just make sure the oil passages line up with the holes in the bearings. I dont think the governor bearings are common things, although I was able to order some from sandy lake impliment. REmember to remove all of the brass stuff before having it tanked. the tanking may dissolve everything that is not steel. best luck

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01-29-2008 05:32:45

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 Re: B engine teardown, and, are cam bearings DIY install? in reply to acsteve, 01-26-2008 14:53:11  
Bought my cam tool from Eastwoods, pricy but useful for many little bushings. Google or Dogpile cam bearing tool. Definitely works brst with a shoulder on it to insure alignment.

Geez Dick, can I borrow you and your machine shop? Got a lot of little toos and bushings I need :) Although I'm proud of my wheel nut wrenches for the B...Can get a 3/4" drive with a 4' cheater on it on them, and get them real tight now.

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