Would Plymouth People Find This Engine Swap Un-Kosher?

[Guest imouttahere]

I want to get a late 30's to early 50's Plymouth, but I never was very impressed with the Chrysler flathead 6. I'd like to put a nice slant 6 in it. But will my Plymouth acquaintances think I desecrated it?

[Steve Braverman]

Why are you not impressed by the Chysler flathead, yet you're enamored with the slant? The flathead makes decent power, is smooth, quiet and very reliable. Parts are everywhere. There is even flathead speed equipment if you look. It would be a lot of work to install a slant 6, what would the advantage be? There isn't much more power.

[Rusty_OToole]

The restorers will think you desecrated it and wonder why you bothered.

There is a guy named Don Coatney who built a 1948 Plymouth sedan with a hopped up 230 cu in six and a 5 speed tranny out of a Chev S10. He drives it all over the country at 70MPH with no problems.

Remember when they dug up that 1957 Plymouth in 2007? He drove his 48 from Tennessee to Oklahoma just to see the unveiling.

There is another nice web site on the flathead hop up by a guy called Blueskies with some mouth watering pictures.

But, to answer your question. I only know of one early Plymouth that got a slant 6 and that was a 1938 sedan. So far as I know there were no big problems and it worked well.

One thing you should know. Whatever car you get, you will have to gut it like a trout and replace the engine, trans, driveshaft and rear axle. Because the engine will not fit the old trans you will want to use the slant 6 and matching transmission. But the new transmission has no handbrake, and the old rear axle has no handbrake. So to get a handbrake you will need to upgrade the rear brakes and you might as well swap out the whole rear axle assembly.

Personally I would keep the old flathead. In fact I have an old DeSoto in the garage and have gathered up the parts to build a nice hopped up flathead 6 for it.

[Rusty_OToole]

If you want to see what the flathead Chryslers are capable of check this out. If a flathead can make it in this whale it can make it anywhere.

http://www.allpar.com/cars/desoto/suburban-1951.html

[Guest imouttahere]

Doesn't the flathead 6 make only about 90 h.p.? A stock slant 6 makes 145 before any hop-ups, and can make a lot more with a larger cam, more carburetor and headers.

[Guest Bob Call]

Imouttahere

Sounds like you have made up your mind and want affirmation.

You won't get it here.

At heart I'm a hot rod guy, but, if you have or get a nice original car don't butcher it. Keep it original or restore it and drive and enjoy it. If you want a hot rod, get a car without a drive train and missing trim and other stuff that would make a restoration a major project. Then get a front subframe from a late model Mopar that has good suspension and disc brakes. Use a Mopar 360 engine as they make good power, are readily available, fairly inexpensive to rebuild, and several transmission options. You'll be happier with that than with the slant six.

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We'll all be drinkin' that free Bubble Up and eatin' that rainbow stew. Merle Haggard 1981

http://www.cmt.com/videos/merle-haggard/26454/rainbow-stew.jhtml

[Guest imouttahere]

"If you want a hot rod, get a car without a drive train and..use a Mopar 360 engine..."

Already have one of those!

[Guest Bob Call]

Chrysler ahould have put this in the Valiants and Lancers instead of the slant 6. I had a 61 Lancer and if it had been factory fitted with a 318 I would probably still be driving it.

[Harold]

They are easily interchangeable from the early 1930's to the late 1950's. Later flathead sixes had 130 HP. Add speed equipment and you'll have a very quick (and different)ride.

As others may have mentioned, if you want to go for the slant, don't chop-up a nice original car to do it.

Harold

[keiser31]

To answer the original question....No.

[bigaadams]

Doesn't the flathead 6 make only about 90 h.p.? A stock slant 6 makes 145 before any hop-ups, and can make a lot more with a larger cam, more carburetor and headers.

yeah..back when the Ford V8 was producing less...and with hardened steel valve seats etc..you are road ready yet today

[Rusty_OToole]

The last Chrysler car with a flathead was the 1954 265 cu in 120 HP.

The first slant 6 was the 170 cu in 101HP 1960 Valiant. It was soon joined by the 225 cu in 120 HP version. I think the most powerful version was the Super Six 125 HP.

So there isn't a lot to chose between the flathead and slant 6 for power.

A 251 cu in version of the Chrysler flathead engine was used in big Dodge trucks until 1962 and in military vehicles till 1968. They continued making this engine for marine and industrial use till 1972.

Dodge and Plymouth cars and pickup trucks (USA models) used a 230 cu in engine of 110 to 120 HP up to 1959.

Chrysler started using modern type shell bearings in their engines in 1934. In fact they get the credit for introducing this refinement when others continued to use the old poured babbit bearings for another 20 years.

In 1937 they brought out a new engine series that lasted as long as they made flatheads. But they did change the design slightly in 1n 1938. So basically engines and parts interchange from 1938 to 1959 or possibly as late as 1972.

Most parts can still be bought from your local parts stores. There is a company called Vintage Power Wagons that is very big on these engines and can supply all parts. Plus there are other Mopar vintage suppliers.

The old flatheads will keep up with modern traffic provided they are in good shape. I know of owners of 1940s and 50s Mopars who were surprised at how well they perform after a rebuild.

[whtbaron]

Anything non-original or unavailable as an option pretty much destroys your credibility for a restoration, so if you're rodding it you're pretty much on your own. In terms of getting it on the road, and if you want to keep a 6 banger, I'd have to agree that a hopped up 251 would be a whole lot less work and still give you a dependable driver that's good on gas. A wide engine is probably going to require a frame clip and front to back torching .