Mike Rimu Posted August 31, 2020 Report Share Posted August 31, 2020 Members 1 10 posts My Project Cars:1939 Chrysler Report post #1 Hi there I just posted this on the truck forum, but in case there is anyone here the can help out as well. I have my engine in the shop getting re built its a 25 inch block engine # T3834402 cylinder block #666029-1 which I understand is from a 37 MC dodge truck . The engine is in a 1939 Canadian Plymouth P8 sedan and I have no idea of the history of the engine or car. I am looking for parts for it but the thing I have problem is the bore size. From the research I have done the bore size in meant to be 3 3/8 but the bore in the engine is 3 7/16 which means that I would need Desoto or Chrysler pistons not Dodge pistons. I am not sure on the length of the stoke but I'm trying to find that out from the shop. Piston pin is 7/8 and the compression height of the piston is 2 inch (center of the piston to top of the crown) with 2 compression rings and 2 oil. The engine is in New Zealand so it's taken a bit of back and forth with the shop for details. I'm here in the States and wanting to get the right parts before I head home for Christmas. I am just a little confused as a couple of places I rang thought that I would need 3 3/8 size pistons when they looked up the T38 engine number. Anyone come across this engine with a 3 7/16 bore? I have no idea what cc it would be I thought that they were 218. Thanks for all you help out there in mopar land Mike Quote Link to comment Share on other sites More sharing options...
Loren Posted September 1, 2020 Report Share Posted September 1, 2020 Well, you can go to Wikipedia under "Chrysler Flathead 6" for a quick look at all the combinations ever made. The 25 inch Chrysler engines that I am familiar with (namely 237, 251, 265 cid) all have 3 7/16 bores. The stroke and connecting rod length is what makes the difference in displacement (the longer stroke requires shorter rods as all the pistons are the same). I am building a 265 right now. I bought two engines a 237 & a 265. The 265 had a bad block while the 237 had a good one, so I mixed and matched the parts which you can easily do. Where it gets confusing are the Canadian Plymouth engines which are 25 inch blocks with displacements much smaller than we got in DeSotos and Chryslers. For parts there are many suppliers and don't forget Vintage Power Wagons for surplus government parts. Hope this helps. Quote Link to comment Share on other sites More sharing options...
9 foot box Posted September 1, 2020 Report Share Posted September 1, 2020 The 3 3/8” pistons with 4 1/4” stroke is a 228 c.i., a 4 1/2” stroke, a 241 c.i. The 3 7/16” bore with 4 1/4” stroke is a 236 c.i. and a 4 1/2” stroke is a 250 c.i. This information comes from a 41-47 W series shop manual. The wrist pin is noted at 55/64”, .016” smaller than 7/8”. So your engine is a 236 or a 250 is my guess. Dodge ton and a half and two ton used these engines. Quote Link to comment Share on other sites More sharing options...
dpollo Posted September 1, 2020 Report Share Posted September 1, 2020 the 3 3/8 +.060 piston carried the same part number as 3 7/6 std. Quote Link to comment Share on other sites More sharing options...
Andydodge Posted September 1, 2020 Report Share Posted September 1, 2020 Mike............ DO NOT tell anyone that its a Dodge or Plymouth engine to start with as that will only confuse the yanks...........all anyone needs to know is that its a 25" DeSoto/Chrysler based engine that has a bore of 3 & 7/16th which equates to a 250.6/251 cubic inch engine and you want pistons to suit THAT size engine..........this size bore used a 4 & 1/2 " stroke to give the 250/251 capacity............I can't give any info re what or where the engine may have originated from BUT here in Oz that bore is quite common on the 25" "KEW" engines that were used from the mid 50's thru to the end of the Oz Chrysler Royals in 1962........all 57-62 Royals with an auto trans used this bore size engine......we also got the 25" engine with the 3 & 3/8th bore giving 228 Cubes ..............BUT please DO NOT mention these bores or strokes in the same sentence as a Dodge or Plymouth 23" engine ..............it will only completely confuse everyone, especially the Yanks.........lol............andyd Quote Link to comment Share on other sites More sharing options...
Mike Rimu Posted September 1, 2020 Author Report Share Posted September 1, 2020 Thanks guys The confusing part of the engine is the T38. When looked up it says that its from a 1937 Dodge truck, so that said I have no clue what actual engine it is. That's why I'm asking to see if anyone has an idea of what it is. I will wait until I hear back from the shop with the length of the stoke, maybe that will solve the puzzle Quote Link to comment Share on other sites More sharing options...
Andydodge Posted September 2, 2020 Report Share Posted September 2, 2020 Mike...........see my reply here and PM message reply...........it doesn't matter what the engine is from which is why you tell no one nothink.............LOL............seriously tho' forget worrying where its from, just tell them that its a mopar engine, more than likely from a DeSoto or Chrysler.......andyd Quote Link to comment Share on other sites More sharing options...
Mike Rimu Posted September 2, 2020 Author Report Share Posted September 2, 2020 Cheers Andy I have heard back from the shop and it's a 4 1/2 inch stoke, so like you said its a 251 motor. Now I know that I will order parts. I will get the pistons from Egge as they have them in stock instead of the ones you have there in Aussie, but thanks for the info. What do you think about this?? Both places I rung about parts when I said that I needed .40 under bearings they suggested that the crankshaft should be welded and put back to spec as it's been flogged out over the years. Also you mentioned awhile ago about a HEI dizzy and weber 32/26 carb. One place I talked to said that the Carter carb that is on there already is good and that swapping them out causes problems. The shop wants a rebuild kit for the dizzy and carb. Are they worth rebuilding or just swapping out?? Cheers as always Mike Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted September 2, 2020 Report Share Posted September 2, 2020 What is the carb number that is stamped into the airhorn flange. Also what is the distrubutor Number IGS-xxxxx You can get a NOS breaker plate assembly and drop that into the dizzy and then rebuild your old breaker plate. There are two bronze bushings that can be replaced but the entire dizzy needs to be taken apart to drive them out and back into the body of the dizzy. Maybe rebuild the advance springs and weights New cap and rotor I might have a Complete Carter Carb Rebuild kit with all of the internal small parts but need to know the carb number and also the dizzy number. You can rebuild the carb yourself and if just replacing the breaker plate you can do that yourself and also set the points gap. This is very easy to do when the dizzy is out of the car. Rich Hartung Desoto1939@aol.com Cell 484-431-8157 Home 610-630-9188 Quote Link to comment Share on other sites More sharing options...
Mike Rimu Posted September 4, 2020 Author Report Share Posted September 4, 2020 Thanks Rich for the offer the engine is in New Zealand. I will get the numbers off the shop then I will get a kit and take it back with me. I do have shop manuals for the rebuild. Mike Quote Link to comment Share on other sites More sharing options...
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