Engines & possible modifications — a poll

[Aaron S]

At some point I will be replacing the 315 poly in my 58 W300 with a 354 hemi I have which came from a 56 Imperial. The 315 will be filled with oil and set aside for posterity as it has the mysterious L8W3 engine number and all the various parts which are specific to these motors and just slightly different from every other 315 ever made... so that little things like the correct carburetor kit do not exist. The big Chrysler engines, in addition to being larger and more powerful, are much easier to get parts for and utilize the same flywheel and bellhousing, making it an easy swap.

[Gordon Maney]

At some point I will be replacing the 315 poly in my 58 W300 with a 354 hemi I have which came from a 56 Imperial. The 315 will be filled with oil and set aside for posterity as it has the mysterious L8W3 engine number and all the various parts which are specific to these motors and just slightly different from every other 315 ever made... so that little things like the correct carburetor kit do not exist. The big Chrysler engines, in addition to being larger and more powerful, are much easier to get parts for and utilize the same flywheel and bellhousing, making it an easy swap.

Really interesting! Tell us more about all this, please.

[Aaron S]

I'm not sure there's a whole lot more I can add at this point, as I have several other projects going on right now that I am heavily invested in and need to get completed before I dive in to building the hemi. I am probably several years out from making this a reality... so many Dodges, so little time, I'm sure you can relate. However there are a few more details I can pass on for those who are interested.

As I am sure many of the folks on here know, Dodge, DeSoto, and Chrysler each had their own hemi engines in the 50's. They are all wonderful engines, however there is absolutely no parts interchangeability between brands (and only limited interchangeability within each individual line due to low deck/high deck blocks and differences between passenger car, truck, industrial, and marine engines). There are however , two common denominators between all of these different motors... the bellhousing pattern and the crank flange (with the exception of the 51 through early 54 Chrysler 331, which has the integral bellhousing cast onto the back of the block). Therefor, while parts will not interchange between engines, the engines themselves swap fairly easily between any mopar products of that era which came from the factory with a V8 engine because the transmissions are common throughout the entire range... even the Plymouths with the oddball early poly engines which eventually evolved into the 318A and later the LA engines. This is why it is relatively simple to bolt any early hemi to a modern torqueflite or its overdrive variants using an aftermarket spacer plate, it is the same bolt pattern.

As an aside, though these aftermarket plates are commonly referred to as adapters I am not sure that is really the correct word. It seems that the more appropriate terminology would be spacer or indexing plate, as all it really does is adjust the the depth of the transmission input shaft into the clutch or torque converter, and sometimes provide a mounting surface for the starter. For example, I purchased my 354 complete with the two speed, cast iron powerflite transmission from the 56 Imperial it was removed from in the factory configuration. There was a 1/4" aluminum indexing plate between the block and the transmission which the starter mounted to. Is it an adapter if it comes that way from the factory?

But I digress. In terms of swapping an early hemi into a Power Giant era truck (or anything else for that matter) if anyone other than myself were obsessed enough to undertake such a thing, I would recommend starting with a 55-58 Chrysler passenger car engine. It will require some frame boxing/motor mount fabrication, but the engine internals are far more readily available. If one could acquire a complete 331 or 354 from a Power Giant era heavy truck (two ton and up) it would bolt right in, but these are exceedingly rare, especially with the truck specific water pump and front engine mount intact. The truck motors also have different heads and intakes (mostly to do with a different heat crossover system from the passenger cars), timing drives, cams, bearing specs, etc. So while a proper truck engine is undeniably cool to the N-th power, the passenger car engine is the way to go from a bang for your buck perspective.

Along the same lines, while any Dodge or DeSoto hemi will fit equally well in the same space, it will be a smaller motor that will cost more to build. Parts are not as readily available because demand is not as high. Similarly, industrial and marine motors have slightly different blocks that are not as well suited to street use. While they can be made to work, it will be a lot more fiddly than starting off with a good, complete motor from a passenger car.

When I got my 58 W300 and started earnestly researching the 315 poly engine that is in it I discovered that the 50's poly engines can be converted to hemis, it is the exact same block after all. It requires changing the heads, pistons, cam, and pushrods, along with the hemi specific rockers, valves, springs, etc. Once I started pricing parts I discovered that a decent set of head cores cost as much as a complete Chrysler core engine (or more)... unless you find an exceptional bargain, just build a Chrysler.

Now that I read back over this, perhaps I should have started a separate thread? A little late now I guess. Thoughts? Opinions?

[Gordon Maney]

Good job, and it's perfectly fine right here!

If you'd like to start an early hemi thread, that would be great, too.

[Gordon Maney]

I also suspect you could write an interesting article for the magazine....

http://www.powerwagonadvertiser.com/submit.html

[Aaron S]

Thanks, Gordon! I always try to write up to the bar that you set for us here, it is an enjoyable endeavor. I may well take you up on that article, and very possibly the point/counterpoint on original vs. modified trucks as well. Its just finding the time (and making it an article not a book, I often get carried away with subjects I am passionate about).

Also, I am by no means an expert on early hemis, I just find them fascinating and I tend to retain a lot of information about things that interest me greatly.

[Gordon Maney]

There is no limit to article length....

[Gordon Maney]

Aaron has a really great article appearing in the next issue!

[Chewie]

My M37 already has a 318A, but it is going to get the fuel injected 318 from my Dakota. Eventually.
My crew cab is getting the Cummins.
The VF is getting a 318.
And the poly is going into the 38 sedan..

All I need now is time...

[Gordon Maney]

My M37 already has a 318A, but it is going to get the fuel injected 318 from my Dakota. Eventually.
My crew cab is getting the Cummins.
The VF is getting a 318.
And the poly is going into the 38 sedan..

All I need now is time...

A useful observation about life.

[Chewie]

All I need now is time...

The older I get, the more that statement means..

All that commuting and OT really slowed the projects down. About all I could do was gather parts.

But things are slowing down for us at work now (we've been on 8 hour days all week), so I just may get some more time to work on things. I actually have the front end of the W200 opened up to swap the power steering in.

[Jason Mills]

I wish we would see some folks use some slant sixes.

I voted for modifications to the Flat head 6 in a WDX... and I had all the basic parts and modification is easier than a transplant at my skill level, usually cheaper too.

That being said, I am in the process of putting a '76 D200 slant 6 in what was an engineless M37.

It is my hope that the slant 6 will combine the flathead's low end grunt, with solid midrange ability and the potential of returning almost acceptable fuel economy (for a 3 ton truck, with 5.83's) hopefully better than the flathead can ever do... if that turns out and the slant 6-M37 becomes the go-to truck because of engine performance, the I may consider putting a slant 6 in my WDX... ether way, once the slant 6 is operational, I look forward to comparing the differences between both 6's.

[Gordon Maney]

I voted for modifications to the Flat head 6 in a WDX... and I had all the basic parts and modification is easier than a transplant at my skill level, usually cheaper too.

That being said, I am in the process of putting a '76 D200 slant 6 in what was an engineless M37.

It is my hope that the slant 6 will combine the flathead's low end grunt, with solid midrange ability and the potential of returning almost acceptable fuel economy (for a 3 ton truck, with 5.83's) hopefully better than the flathead can ever do... if that turns out and the slant 6-M37 becomes the go-to truck because of engine performance, the I may consider putting a slant 6 in my WDX... ether way, once the slant 6 is operational, I look forward to comparing the differences between both 6's.

I hope you will take pictures and do an article on the slant six conversion!

[Jason Mills]

I hope you will take pictures and do an article on the slant six conversion!

I will be happy to do so, And I think it would be fun to attempt a comparison between the two sixes once done.

[Gordon Maney]

Wonderful!