Can anyone help me identify a Plymouth flathead 6? The number on the block is P25*125953*. Also, the head (dated 11 3 52) has casting number 1405849-4. There is a D and an N, and an arrow in the casting points to the D. What does that mean? The head also has a large A and a P and I suppose that the P means Plymouth. Bore is 3 1/4" and stroke is 4 3/8".
p24 is a 53 the 1 designates a Cambridge model, ad the 4 3/8 stroke make is t 217.8. 230's were introduced in 54 in the Plymouth line. The date on the block indicated it was cast in 52. Low sales probably carried over the block castings till early 53.
Thanks. I suspected that this was a later engine (it's in my '49) when I got the car, but I never really looked until I pulled the head today. This motor has the later thermostat housing (looks like a tube on a flange) instead of the earlier, cast rectangular housing. I hope to find one of those as I think they look better.
There are two bypass systems involved here, the whys and wherefores of what got which are a MOPAR mystery. My 46 engine used the internal by pass system. I bought a bunch of parts for a 48 dodge engine and it had the external set up the one with the square castiron deal and the short tube between it and the water pump. the 56 engine I am now using had the internal deal. So you cant say early or late applications. Now that said, you can't mix and match without addressing the plate on the rear of the water pump. The pump with the hole in the rear plate is for the internal set up. The external set up has no hole.
Yes that makes sense. I might be better off with the internal setup even though I like the looks of the other one better. IIRC the external used a hose with an oddball diameter. You'd often end up using a hose that was too big and then scrunch it down with the clamps. Not good.
You guys did such a good job of ID'ing that old flat 6, I'm going to try another one. There's a couple things working against me in terms of finding the exact size without opening it up.... a) it's probably Canadian built, and b) it came out of a 54 3/4 ton pickup. The block number is T-339 1195C. From what I can find on the web, it's most likely a 228 or a 251. Can anyone pinpoint which one from the numbers, or will I have to pull the little plug over #6. I believe the 228 has a 4 1/4" stroke while the 251 has a 4 1/2" stroke.
The casting number on the head is 253, with the numbers 1327337 under it if that helps. It's a 25" block, but Canadian trucks were also known to get smaller sizes with the longer block.
Reply from another forum... thanks Rusty! T339 is a 1954 - 56 Canadian made Dodge truck engine, 228 or 251 cu in. Can't pin it down any closer than that. The 228 has a 3 3/8 bore X 4 1/4 stroke. The 251 has a 3 7/16 bore X 4 1/2 stroke. Both use the same engine block and the 3 3/8 bore block can be bored to 3 7/16 or larger. There was also an engine with the 3 7/16 bore X 4 1/4 stroke, this was a 237 cu in used mainly in DeSoto cars. Not used in the 54 - 56 truck line.
Just a FWIW...if you need more detailed info on this L6 you might try a Mopar forum like www.p15-d24.com or https://groups.yahoo.com/neo/groups/39-47Dodge/info .
Another FWIW: I bought a new old stock set of flathead V8 pistons, 296" (3-3/8" X 4-1/8") no rings. My friend Don at the San Jose speed shop furnished 2 sets of Dodge 6 cyl. rings, (Grant) which fit the Silvolite V8 pistons perfectly. Dodge rings were available, and cheaper 'by the dozen'...
For now the speedster still needs to be built and the engine runs so I'm going to give it the spray bomb rebuild. Some where down the road I might mill the head or get a finned one, and bore it out to 3 7/16 so I can use the 251 pistons and rings... they are still available. I'd like to wire this thing for 12v neg ground so that's a bit of a challenge with the starter. I've got a generator and regulator from a late 50's IHC I can use.
Yea, I have heard that before as well. I was wondering if switching to negative ground was going to be an issue but apparently not. The solenoid will have to be switched to a 12 volt unit though. I had wanted to ditch the truck's engaging pedal for the starter at the same time, but I can live with that and it might look kind of cool on the floor of the speedster. I've also been told I need to run a resistor with the 12 volt coil or I'll fry points.
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