Hey all: In the February 2008 issue of Hemmings Cl***ic Car, there was an article about a 1950 Plymouth P-19 Deluxe fastback. I kinda liked the body shape, 'top hat' and all (while the article actually said that the Plymouth executive actually said "Cars are made to be sit in, not pissed over." I was looking for prospective winter drivers, and the Plymouth sounded good, given that they are much cheaper than comparable Fords and Chevys and have VERY high rear axle gear ratios. It would have to be (dare I say it?) a beater with little more than a good heater, because if it doesn't start off ugly, some Boston road salt will make it ugly real quick. You can't drive a roadster all year long, unless you have a real nice coat! However, I balked when the article mentioned, "...About 45 mph is a comfortable top speed. Above that, the engine begins to howl in protest...". That won't do! I've read about blueskies' cool sedan and all of its hop ups but aside from that information seems to be very lacking. Anybody got photos, links, info, personal stories, or anything else related to the mopar flathead six? -Stizzealth
I can't say for sure what the top "comfortable" speed would be but I would guess more in the 60 to 65 range. Perhap higher if it has overdrive.
I have a '51 plymouth with a stock flathead 6. I feel very comfortable at 60mph and ***uming the tach is somewhat accurate, it's turning approx 2600 rpm. It has seen 65 mph but I wouldn't run it at that speed for very long. I tried to attached pics, but the files r to large to upload.
Some of them have real low-geared rear ends. My '50 wagon came with a 4.11 and wasn't happy much over 50mph till I put in an overdrive. They're not high-rpm engines. Now very happy at 65mph.
Here is the new engine with R10 OD that will be going into my 48 Plymouth Coupe in a couple of weeks when my work travel schedule slows down. My current flat 6 and 3 speed will run highway speeds around Dallas. Speedo is not reading correct but knowing how traffic flows when driving my wifes car I can say that I can run it at 60. It is reving a bit but it seem fairly comfortable. Got the intake, carbs, headers from Langdon's Stovebolts. I know that an 8 3/4 from a from a 65 to 70 B Body will fit in my 48 with only moving the spring perches. Not sure if it would fit the 50 as well, but it would give you much more selection in gearing.
Stizz. I think you will find that keeping the revs in check is the issue. A lot of older Mopars use the overdrive transmission and some have added a T5, 5 speed ******. Look up Don Coatney on www.olskoolrodz.com. Not sure if he is one the HAMB. He has a '48 Ply. with a 251 and a T5. And Like Blueskies he has his car on the road all the time. N B R
For spe******ed info, you want to take a look at the forum for Mopar flat sixes at www.p15-d24.com There are several Hambers there, including ******knuckles, Blueskies, Don C, and myself. My '55 Plymouth has a 230 engine with 3.73 rear, and will sit happily on 60-65mph, but starts to howl at 70mph. You can find your diff ratio stamped on the front of the pumpkin, at the top.
Agreed with the others, 60-65 is a very comfortable speed. You start to feel a bit uneasy much above that. Flat 6's are probably the most reliable of the straight 6's. They were produced up through 1972 (..I believe) and have been used in multiple applications. I have 2, My wife's 251 DeSoto and my 218 Plymouth; Oh, and with overdrive I have achieved 26-28 miles per gallon in my Plymouth. Good luck. ******Knuckles
MOst of the hiway trouble with early mopars is in the rear end not the engine. Remember when these were built, the average speed was probably about 45. I have a 46 with a 56 230 but the stock 4.10 to 1 rear end. I drive state hiways all the time at 60 to 65, 235 r 15 rears. It runns about 3100 according to calculators. Drove it to Charlotte from Upstate NY last year. No troubles 19 mpg with about 300 lbs of stuff in the trunk. Keep oil in make sure the timing is adjusted so there is no spark knock (ping) and it will goo for a good long time. 65 is OK 70 is pushing it.
I have the stock flat 6 still in my '53 Plymouth wagon and I tell ya, best motor I have ever had in any car. The thing just keeps on running. Just recently had the head down, blown head gasket but, it was still running. I cruise around 65 mph and kick it in the slow lane and laugh just watching them rice rockets blow by me and then see a Highway Patrol right on their ***'! KNUX!
My car came stock with 3.73, like other's have said 60-65 was a good cruising speed. Then I put a 3.54 gear in it and I regularly cruised at 70 sometimes even 75 for a bit. Now I have an stock overdrive with 4.11 but I haven't got it back in yet. Should be real calm at 70-75 now though. I have done some calculations and figured out that at 75 with the od kicked in it's running 2429 rpm. Which is like having a 2.75 rear gear without od. The od is a 33% reduction. Cruising any faster than that with un-rebuilt suspension and stock brakes and lap belts is pretty stupid IMHO.
I drove a 49 special deluxe to College for 2 years and I did about 10 miles of highway twice a day. Very comfortable at 60 miles an hour. A little beefed up and overdrive and you'll have no trouble going faster.
I, like a few on here mentioned, put a T-5 behind my mopar 6. Just finished last Friday and drove it about 250 miles this weekend and love it!! Not too sure what RPM's I'm doing at what speed, no speedo yet but keeps up with traffic about 2500 RPM's.
I have to agree with the rest of these gents. I own a 1948 Desoto deluxe club coupe and she can drive around at 60-65 on rocky moutain highways all day long! It seems to be a more plesent ride than stop and go in town with the old fluid drive behind it anyways.
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