Help Decoding Flathead 6 Engine on 40 Desoto

[40desoto]

Can someone help me decode this engine number?

N174384CAL

An engine on my recently purchased 1940 Desoto Coupe.

I was under the impression all Desotos has a prefix of 'S'

[Young Ed]

That looks like a restamp possibly done by the state of California.

[desoto1939]

Hi,

i own a 39 Desoto and onthe engine block where you have your number the first tow digit should be S7. My 39 Desoto is a model S6 and the 40 is a model S7.

Where are you located I live near Valley forge PA. Send me you home email address so we can stay intouch with each other.

Rich Hartung

Desoto1939@aol.com

[40desoto]

I figured there was something really weird about there being a 'CAL' in that number. I cant find the VIN anywhere on the car but on the title the VIN is the number on the block?... So if I ever change the engine out I will no longer have a VIN?

Block = N174384CAL

VIN accoridng to Title CAL174384N

[Guest P15-D24]

on the drivers side of the block.

[40desoto]

That is the casting number on the front drivers side of the block

Ill post picture in abit

[Young Ed]

I figured there was something really weird about there being a 'CAL' in that number. I cant find the VIN anywhere on the car but on the title the VIN is the number on the block?... So if I ever change the engine out I will no longer have a VIN?

Block = N174384CAL

VIN accoridng to Title CAL174384N

Thats probably how you got that number in the first place. A lot of states titled vehicles by engine number rather than serial #(vin's werent invented yet). So if you got a replacement engine or there was a title problem the state assigned you a new "vin" which was then stamped into the engine.

[Rusty O'Toole]

The serial number is stamped on a pad on the left side of the block, just below the head, at the front, between the first and second cylinder. If it is not clear you can gently clean off dirt and rust with sandpaper or steel wool then highlight the numbers by rubbing with chalk. A strong light helps read it off too.

Your original engine had a number starting with S7 as DeSoto 39 already pointed out.

If it has been swapped out, it could have a P (Plymouth) D (Dodge) C (Chrysler) or T (Dodge truck) or even an IND (industrial) engine.

[Guest P15-D24]

That is the casting number on the front drivers side of the block Ill post picture in abit

It may have a small clock like an icon next to it. Numbers wii be like 1119729 or 1326299 or 1484829.

[40desoto]

Hi,

i own a 39 Desoto and onthe engine block where you have your number the first tow digit should be S7. My 39 Desoto is a model S6 and the 40 is a model S7.

Where are you located I live near Valley forge PA. Send me you home email address so we can stay intouch with each other.

Rich Hartung

Desoto1939@aol.com

Hey Rich, Im in So. California. Im still debating whether to keep the original drive train or change to v8.

my email. mcerda918@gmail.com

Have you modified your suspension at all?

[52b3b Joe]

I'd keep it original, we have a 41 Desoto, still has the 228 flat six and drives as good as a new car. It has no problem with modern traffic and mechanically you can get nearly all the parts. IMO

[40desoto]

I'd keep it original, we have a 41 Desoto, still has the 228 flat six and drives as good as a new car. It has no problem with modern traffic and mechanically you can get nearly all the parts. IMO

I think Im going to attempt to do that first.. Since I cant decode the engine back to the year on it is there anyway of telling what size the motor is?

The person I bought it from mentioned that it had the original engine but given it looks like it has been re-stamped how can I tell?

[52b3b Joe]

I'm pretty sure that all the "bolt on" (distributor, carb rebuild kits, ect.) components of the engine are the same for all the long block Chrysler sixes. If you order parts, ordering for a 40 should work. If you are doing major mechanical work, once you pop the head and measure the bore and stroke you will know for sure what you have. If you contact a parts vendor to order parts, let them know the situation and (if they're good) they should be willing to work with you.

[greg g]

On the cylinder head above #6 cylinder is a pipe plug screwed int othe head. Removing it gives you access to measure the stroke of the engine. Remove the spark plugs so you can spin the engine manually with fan. Remove the plug and insert a stiff piece of wire about 8 inches long. rotate the engine through a full revolution and you can measure the travel distance of the piston. Desotos of the 40 all used a 4 1/4 inch sroke.

Chrysler use a 4 1/2.

If you pull the head the piston on ths small DeS engine (228 ci) was 3 3/8 and 3 7/16 for the 237 ci motor intorduced in 42.

chryslers used 3 3/8 for 242 ci and 3 7/16 for the 251

But as noted the bolt on stuff should all be compatable. To order tune up parts that the distributor number to the parts store it should start with three letters followed by numbers. Iat Iap and igs are typical. But body style, cap design, and points location are different among them.

[choptop40]

I've got a Chrysler six pulled it out of a 50 dodge abandoned engine swap sedan....it's the 25 inch longer engine...no vin stamp on the block?....yours could be factory replacement...hence rest amped by California laws .....

[dpollo]

on the Plymouth, the original engine number is stamped on the frame about a foot behind the left rear axle.

 

This was intended to be a hidden number so clean the frame really well and use a powerful light.  It is on the vertical face of the frame on the outside.   Also there is a part number  L for left side.  The RHS has the same  number prefaced by R.

Engine prefixes generally used the engineering code as a prefix  like P23.  K L and M were used in Canada in 57 58 and 59.

 

I would guess Desoto would be the same so look for a number prefixed with S.    Many states and provinces used

the engine number as primary ID.  Kinda dumb in retrospect.

[40desoto]

Ok so here I am 5 years later, 4 engines after, and a bit more knowledge about the car.  I have a question regarding the engine in question on the original post;

i have the engine completely disassembled and didn't measure the stroke before taking apart.  Can you tell the size of the engine by looking at pistons, piston rods or anything else?   I hope this is not a no-brainer question.

 

Edited August 8, 2017 by 40desoto
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