The Stovebolt Site Forums The Parking Lot Big Bolts Engine/Head Interchangeability 1939 VC-1937 Sedan..

Just before removing the engine of my 1939 (VC) truck, I decided to give it one last try and see if I could get it unstuck after soaking in mystery oil for about 6 months...To my surprise, I was happy to find that I could finally turn it over!..:) So I removed the pan, cleaned the crud and made all necessary preparations to get it running. After a few days of mostly cleaning and setting up a new battery tray, fuel lines and carburetor (from my other truck) I decided to crank it over. ..

Well, As it turns out I almost got it running, but after a compression test I found that #2 was at 0 psi and #5 at 15 psi... It is never going to run! So, I removed the cylinder head and found that the biggest problem is rust around the valves which equals a complete overhaul of the cylinder head $$$...

That in turn let me to proceed to plan B, install a 1937 216 engine from a sedan in the big truck and I find the following:


1- Crankshaft recess for pilot bearing is smaller since it has a 3 speed transmission. The car engine takes a roller bearing, the truck a larger needle bearing @#$%!@!! ..;(((

So now, plan C if at all possible:

1- Remove cylinder head from 1937 216 (Sedan) engine and install in 1939 216 (VC) block...

A) Is it interchangeable?

If so, I still need to remove the oil pan and push all pistons through, hone the cylinders, get new rings and put the whole thing back together... If the cylinder head is not interchangeable, I have to rebuild the original cylinder head which is quite expensive... This has turned out to be a royal pain in the _ _S!!! What a bummer...

Yes the 1937 head will fit a 1939 bock just fine. Should even be the same casting number. Keep all heads, even the crusty ones as they can and will crack so spare have value. Keep the lifters numbered and matched with rods if you can.

A quick clean of the bottom end and shim adjustment on the rod caps might be all you need. These engines are pretty durable.

A head job may not be as bad as you think once they actually clean it up. The head was regularly serviced back in the day as part of a refresh and the valves are readily available. Both versions of the pilot bearing are available new as well and are cheap so you might be able to mix/match with your trans input shaft.

Well, that is great news... I will use the 37 head with the 39 block, but with all the 39 (newer) head components... lifters, rods and rocker assemblies. Here is the question of what to mix and match. I can use most of all 37 components, rods and rocker assemblies or just the 37 head with all the other stuff...

I numbered all the push rods and left the lifters in place... As for re-assembly, I have to read up on the connecting rod shim adjustment... Can you have (forward/backward) movement with the rods properly shimmed ? or that type of movement means re-shimming? The problem is, what happens if you remove a shim but still have to add something else... Is there a shim kit available for this purpose?

I have seen 3 types of pilot bearings so far for car and truck engines... Two styles for automobiles (Bushing and roller bearing) and a single style (Needle bearing/caged) for trucks. Someone please correct me if I am wrong, but anything with a 4 speed crash box will have the (Hyatt) needle type bearing... It is a shame that it is located in the crankshaft and not the flywheel making truck and car engines unique to one another and not interchangeable...

Philip,
Unless I misunderstand you I think you have confused push rods and connecting rods. If you have removed the head, re-use the push rods and re-install in the same hole and with the same lifter. Do not mix up the relationship of the camshaft, lifter and push rods. There are no shims on the push rods.

There are actually two types of pilot bushings. The original type is made of sintered brass, the later type has iron mixed in. The better one is the former without iron and the way you tell is with a magnet. If a magnet is NOT attracted to the bushing that is the one you want. At the parts house I used when dealing with this they had both types on their shelves. I noticed that the preferred one had "HD" at the end of the part number, perhaps standing for "heavy duty". I am not sure this is true for other brands, just sharing this in case it helps.

I believe all 37-40 heads are the same, so you can mix and match parts as you want. I would select those that appear least worn.

Kent

Hello Kent,

I have edited my previous post to state "push rods" instead of rods to avoid confusion with connecting rods... I numbered all the push rods and kept the rocker assemblies (front/rear) together. As for shims, I was referring to the shims used on the connecting rod bearing caps... Since I have to push all the pistons out to hone the cylinders (39 Block) , do I worry about re-shimming or should I install as found?

Can you have (forward/backward) movement with the rods properly torqued/shimmed ? or that type of movement means re-shimming? The problem is, what happens if you remove a shim but still have to add something else... Is there a shim kit available for this purpose?

As for the pilot bushing, only the Hyatt type needle bearing apply to my case, since I have a 4 speed crash box...

I was referring to connecting rod shims when you get to the point of cleaning the pan and bottom end. The rod will just move to the side with a light tap from a hammer. Get the details from the shop manual and it's actually not very difficult and works very well to get the correct clearance. Easier than Plastigauge for these.

The shims are still available. NAPA had them last time I looked but also Ebay, Chevs of 40'a, The Filling Station, etc. The odds are you will be removing shims and the current ones should be in layers so you pick a layer off but leave the other layers.

Back before the days of Plastigauge the rod shimming procedure was to sandwich a small piece of .002" shim stock between the rod cap and the crankshaft (about 1/4" wide) and add/remove shims until you can turn the crankshaft with a firm pull on the flywheel. Remove the checking shim and move it to the next rod. "Rinse and repeat"! That procedure is a lot more accurate than the "tap it with a hammer" method. New shims appear to be a solid piece about .015" thick- - - - -they're not, but the stack of .0005" and .001" shims are stuck together very tightly, and you'll need something like an X-acto knife to peel away individual layers. It's OK to use one less shim layer on one side than the other if you need to split the difference between adding and removing an equal amount on both sides of a rod cap.
Jerry

Here is an interesting bit related to the clutch pilot bearing and crankshaft for 37-39 cars/trucks... Receiving the clutch aligning tool and new Hyatt bearing (GM 142655) helped me clear things up; it seems that I was mistaken about my statement before affirming that the 3 speed transmissions use a smaller pilot bearing or bushing.. Incorrect. As it turns out the clutch tool fits inside both the Hyatt style bearing, GM 142655 and the ND 7109 or GM 907109..

So, the only difference seems to be that GM 907109 pilot bearing is paired to crankshaft GM 838345 for the year 1939, but I don't really know which crankshaft corresponds to the Hyatt style pilot bearing 142655... Even though my truck is a 1939 model, NOT equipped with GM 907109 bearing, but with the Hyatt pilot bearing in the crankshaft... How can that be?

Furthermore, to make things more confusing the book has a note, for pilot bushing GM 412562, All 1939-1951 (Except P.G.) "When installing this bushing on jobs equipped w/ Hyatt bearing 142655, omit 473681 stop spring...

By stop spring do they mean what appears to be a small plate/washer that fits against the Hyatt bearing? Last two photos...

canadiantim In 1970 Iwas the last full time crankshaft grinder in Vincennes Indiana at the time we offered portable grinding (in the car) or we had a floor machine at the shop.That portable was mostly outdated by high compression engines. we had semi-finished babbitt rods so you could bore it to fit what ever size the journal cleaned-up at. that boring toolwas areal dandy (so simple) it would cut that babbitt slick. Now my teacher suggested the light hammer tap method and he said if you get 10 or 12 lbs. of oil pressure your doing good. We done a lot of dirt track work along with domestic,we offered measuring service and you would often hit undersize stuff around town. We also ground every Mack truck head the local dealer took off. Got Detroits too !