1937 Engine repair

Randy/In

Randy/In

Senior Member
I am doing a clean up on a running 1937 flathead engine with 1936 heads, I would like to reuse as many parts over on this engine. I purchased the engine from a running truck, the compression was low at 78 to 83 lbs. I pulled the oil pan and found 3 cylinders rusty on the bottom, then pulled the heads and found domed heads with flat top pistons (low compression). I removed the carbon from the top of the cylinders, and their is no ridge. the piston to cyl. clearance is .005" after honing one cylinder .001" it removed the rust but their is a little pitting left which I think will be ok. I will either replace the pistons or the heads. I would like to know if the pictures show normal wear on the rod bearing that I removed. I will be taking the engine farther apart to hone all cylinders and rering the pistons. I will probably have other questions. Thanks Randy
 

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Just an opinion, here, from another guy that tends to re-use parts that check out ok... I would say that LOOKS probably don't determine use or non-use (Sorry, Lawson, just my opinion). If this were a sbc or sbf, the looks would indicate to replace. However, for a flathead with 'floaters', I'd call this pretty normal looks. Experience from here suggests that MOST bearings (floaters) that get replaced, probably don't need replacement. My suggestion would be to do some careful measuring - shell thickness, rod big-end diameter, and crank diameter. Go from there - if the clearances look acceptable, then I'd take a chance on them. Basically, do the checks that you can find in Ron's book, or Lawson's book (or many of the other flathead books). This is the sort of choice I would make, only for my personal engine.
We've got an old flathead guy in our RG (a good 10 years older than me, and I'm over 70), who I watched put a flathead together for himself, using parts that he 'hand-selected' from a junk pile laying in his slavage yard. Admittedly, he was careful with his selection, but still, the parts came from laying in dirty junk piles. He put the engine in a 40, and it has been just fine, for the approx 10 years that I have known him. My point... success is possible, just be careful.
JMO
 
Looks fairly normal to me for an old engine. Pretty obvious from the scratching that there was a good bit of dirt in the oil. If it was me, I would replace.
 
I have a small ford booklet that details taking a engine apart,checking the parts for wear and using the parts over again if in tolerance,I think they did this for factory rebuilds also. Don
 
The Ford shop manuals say if the parts are within tolerance, you do not have to replace. We are wealthy today and replace everything wether it needs it or not. I for one do not replace unless broken or out of specifications. I have had excellent results for 60 years.
 
For what I can see the brg. looks pretty good, the light marks are original color, i'd call it every little ware. I think if i remember right the thickness is .110 on a std. brg. Mic the thickness. If you don"t have a ball mic, take someting round like a flathead wrist pin is .750 put the pin inside the brg. and use a one inch mic and mic the thickness at the crown of the brg, should be .860 for a std. brg. Walt
 
i have flat pistons with domed heads in my 36 pickup, i don't think there is a lot of compression , its a 35 motor and it seems to run ok!
 
Thanks for all the feed back. I will finish tearing down the engine over the next week or so, clean and measure all bearings, main and rod journals, con. rods, and other parts as needed. the crank is .030" under size main and rod pins, The pistons are .080" oversize. so far I see four cracks between head studs and water passages. The valve lifters are non adjustable, with the two peice guides. So it looks like I have a good winter project to do. Randy
 
They Look OK to me as well, Use a scuf pad or 400 paper to clean them up. Wash in soapy water. Measure as Walt said. I use old bearings in all my floaters if I can find them. Noe with that said if you need a standard bearing i have a box full of them. PM me.
 
Randy/In said:
Thanks for all the feed back. I will finish tearing down the engine over the next week or so, clean and measure all bearings, main and rod journals, con. rods, and other parts as needed. the crank is .030" under size main and rod pins, The pistons are .080" oversize. so far I see four cracks between head studs and water passages. The valve lifters are non adjustable, with the two peice guides. So it looks like I have a good winter project to Randy, if the rod brg are .030 each half will be .015 thicker tand std. or .125 Walt
Click to expand...
 
Did you remove the sludge?? The first picture is the sludge removed from an original low milage 38 engine that had no bearing wear, 100 lbs compression and good valve clearance. I hosed it out with diesel fuel and a parts washing gun after scooping out the sludge. This was typical of the old engine oils. Replaced the main and rod bearings with a set of NOS standard sized ones which were very inexpensive because there are not many standard sized crankshafts and a lot of standard bearings available. I removed the oil pump and tested it, put in Castrol 20/50, removed the plugs and with a mechanical oil gauge spun the engine with 12 volts. Oil pressure was low, I knew the bearings and pump were good so I shimmed the oil pressure relief spring with a 3/16" long piece of 1/8" pipe and adjusted the length until I got 55 lbs of oil pressure. I soaked this engine with MMO several times over a 6 month period before I started to free the valves and rings if any were stuck. The second picture is my 39 convertible engines bottom end. At 75,000 or more miles I was changing the oil and stuck my finger in the pan to feel for grit in the pan. I felt something move and went back in and the oil screen and tube fell off. I removed the pan and this is a picture of the bottom end. There was not a drop off sludge in the pan or anywhere. There was a spot of thin hard dirt about 2"s in diameter near the drain plug. I now have over 110,000 miles on this engine with Castrol 20/50 in it since start up and it still runs perfect, no noise and burns no oil. A lot of driving at 65 to 75 MPH for 10 hour days in 90 degree plus temperature. The engine runs in the 165 to 180 range and the water stays filled up to the neck for over 6 months with Skips pumps and a good working 4 lb pressure cap. Needless to say with all the posts on "new oils" I'm sticking with Castrol 20/50 which as far as I'm concerned has proven itself. Notice the "39" engine was a new raised intake WW11 engine from Carpenter over 30 years ago. There are no freeze plugs in the pan rail as discussed in several past posts. G.M.
 

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The oil pan had about 3/4 inch of sludge, and the valve valley has very little sludge. when I get the engine apart I will clean it with a hotsy pressure washer and a vapor degreaser I have at work. Thanks, Randy
 
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