1958 Dodge Coronet - Moving from Flathead to a V8

IronMighty

IronMighty

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Another one of my numerous C body projects that I'm getting round to think about and start looking for spares for. I've got a 58 Coronet hardtop which is entry level specification with the Flathead 6 and 3spd manual column shift. I'm thinking to swapping to a V8 but keen to understand what transmission options there are if I want to retain the column shift manual?

I'm UK based so I'm a little limited in terms of what might be available(was sire tempted by a 413 for my 61 Dart that's available over here) so welcome any input whilst I search.

Many thanks in advance.

20240525_180925.jpg
 
At one point in time, 1975 or so, a friend was looking to start a mobile photography operation and wanted a reliable car that was inexpensive. He found a '50 Plymouth sedan in a lady's back yard. Been there about 10 years or so, so he paid her $25.00 and got it hauled to his place, where we started to get it ready for use.

As a part of that, I asked the local Chrysler service manager if he had any knowledge of that car. I also asked about alternatives to the flathead 6 in it. That's when he mentioned "early Hemi" V-8s and the I-6s had the same bellhousing bolt pattern. Now, fast-forward to 2023 and some Uncle Tony's Garage YouTube segments on the Poly A motor, noting that that motor, being "early Hemi-based" had the early Hemi bolt pattern, which then carried into the LA motors' bellhousing bolt pattern. Which I also believe ALSO carried into the current Gen III Hemi bellhousing bolt pattern.

It appears a BIG issue might surface in the realm of rear crankshaft/flywheel/clutch mechanism area. There is a good bit of difference in the earlier torque converter attachment issues, so there could well be in the manual transmission clutch area too.

You might want to look at the appropriate model year factory service manual and parts book to get an idea on these things. Then possibly somebody with more knowledge of Forward Look cars than myself, in this area.

Just some thoughts,
CBODY67
 
You will have to stay pre 62' for your drivetrain, as the crank/bellhousing/clutch assy is unique to the model.
an older polyhead would work if you could find a parts car you need, mainly everything North from the bell going forward. Most people just drop in a newer drivetrain, and can the rear end and emergency brake setup that is on the rear of the transmission as well.
 
I'd get a newer drivetrain ...engine and trans...GENIII HEMI n trans from a RAM...
 
A lot of the old Poly motors did not come with the crankshafts drilled for a pilot bushing. If the motor came with an automatic originally you might have to get a machine shop to drill it for you.
 
BuckeyeBarracuda said:
I have an extra 325 motor from a 58 Dodge with a Powerflite transmission if any interest (Ohio)
Click to expand...
I would be interested if nobody has claimed it yet.
I tried to PM you but it says I reached 15 conversions and could not reach you.
I don't know what that means but if you want send me a message here.
Thanks.
 
I cleaned mine out last night. Maybe you need to do the same? I find the cleaning of the postal boxes to be a very confusing part of the site... Let me know if that doesn't work...
 
Six cylinders and V-8s had different frames I am guessing because of motor mounts like the later cars with K-frames and sub-frames.
 
Was it actually different frames or different set-ups for the motor mounts? I have had a few 56-60 v-8 poly engines, but no 6cyl, although I know they are very different in motor mount set-ups...
 
I went to my parts manual and they show 6 cylinder frames and 8 cylinder frames. The only '58 frame shown for sixes and eights is for '58 DeSotos and I never knew they built 6 cylinder '58 DeSotos. I got into the frame differences when I wanted to set up a '59 Suburban 2 door wagon for drag racing with the 361 out of my '59 Sport Suburban.
 
The frames are the same. They list them differently because the brackets for the different motors are welded to the frame. You would need to cut off the 6 cylinder parts and weld the parts from a V8 in place. Everything else is the same. There are differences between frames on different models. The converts. have an X piece added for strength. 2 door hardtops have boxed frames from front to back and some models have a frame that is not boxed all the way.
 
I will say that a flathead 230 powered '58 Coronet is way cool because of its uniqueness. Another option would be to put a 5 speed manual w/ floor shift behind that engine - it would make it seem like a different car. You can easily find parts for that engine and trick it out with things like a two-carb intake, headers / dual exhaust, etc.
 
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