VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 38 Master Engine Surprise

I dropped the pan on my 38 Master tonight to deal with the rear main oil leak. To my surprise I have a proper rear main seal, not the open slinger arrangement. Now the cross member for the torque mounts fits just fine with the pan. I am used to reading that the later motors have pans that interfere with that cross member. Also, I have to remove the starter to look for some numbers. In the meantime, is it possible that this is a 1940 - 42 motor?

What is the engine serial number, the block casting number and the block casting date?

If the oil pump pipe and screen is bolted to one of the center main bearings it is a 1940 or later block.

Dog, That was the exact same question you asked me back in 1997 when I started the restoration of the 38! That's when I discovered (you discovered) I had a 51 block and a 41 cylinder head.

Sorry, off topic but it brought back a lot of memories.

Thanks again for all the help, It would not have been possible without all you guys!

Brian

Although I haven't found any relevant numbers yet, the oil sump assembly is indeed attached to the thrust main bearing cap. I always thought that the switch to the rear main seal coincided with a longer pan that would not fit with the 38, but obviously I was wrong. I am going to remove the transmission and get it overhauled now that I have gone this far. I will be installing some new bearings and an NOS wick seal.

I have been working on my main bearings and main seal. At least half of the main bearing bolts had lock washers that fell off in peices. I just was thinking how dicy reusing them would be.

I would get new American made lock washers.
The 1940-1947 engine has wider connecting rod journals than a 1948-1953. Also slightly different main bearings.

This is all a bit strange. I have a 38 with a 48 motor. The earlier motor simply has a drain plug on the LH side halfway down the pan. The later motor has a drain plug down the back halfway across the pan. I have a friend who is working on a 39 which he says has an original motor but I glanced underneath and saw a later motor. It did not foul the cross member. It is a close fit and I gather that some people modify the pan, others the cross member. Beyond having a rear seal rather than a slinger there are many differences with so many parts not being interchangeable.

Today I received my July issue of G&D. I read with great interest Gene's excellent article on the 216 oiling system and history of changes. I checked and I have the small plate on the side of the block for the oil distributor and my oil line feed for the rocker arm comes out and loops around to go back through the block to the side cover area. This and the fact that I have a rear main seal is leading me to believe that I have a 1940 motor.

I have to correct my statement above. I believe that I have a 1940 to 42 motor.

The casting number will clear-up the mystery. It is on the right side of the block between the fuel pump and distributor. Large raised numbers easy to read wit engine in the car.
1938=838710, 1939=838941, 1940=839132, 1941=839400, 1942=839910, (also up to 1947) 1948 and 1949=3835253, 3835309, 1950-1951=3835497,

Then it would be intresting to see if head matches the block. Casting number under valve cover, left side, easy to see.

If block is from 1938-1940 it will have domed pistons. 1941 and up has flat top pistons. If flat top pistons are used with a 1938-1940 head you will have a very low compression ratio,
1941-1948 heads had the tiny 10MM spark plugs.

Chevgene,
I found the number, thank you. It is 839132 and I see that would be a 1940 block. All the compression readings are around 95 PSI so I would think the head is correct. I will have to look at the Canadian casting numbers because I think they might be different and this is probably a US casting.

839132 is the US and Canadian casting numbrt for a 1940 block.

Chevgene,
thank you. It was an interesting time finding the number. The number isn't really visible from the above view because the block has a ridge above that point and the side of the block is in towards the middle a little. The fender prevents a better angle for viewing. However, I found the number area on my spare motor and then read the one on the car with a mirror.

Hello folks,

sorry, my question is completely out of this discussion, but close enough to ask:

In past there did exist a website where all ever built engine numbers were listed. As well frame numbers.

I did add the website to my favourites and a partially printout was very helpful when I went to register my 1940 in germany which did came from US in december 2010

Sometime ago I tried to help a friend (an old man without internet) owning some old chevies to find out more about his cars but instead of that website I got only errors like "website removed" or "not found". Does anybody know where it is gone? What is your source to discuss about engine and frame numbers?

Regards
Stefan germany

The person who did that site passed away.
US cars did not have a frame number stamped.