upgrade to my 51 Cambridge

[amp56]

anyone ever use a jeep 4.0 in one of these ? I have motor and trans even rear end and I know they have a lot more power the the flatty plus adding a /c would be lots easier . will I still have to move steering ? I also need info on front disc

[amp56]

  On 3/8/2025 at 4:10 PM, amp56 said:

anyone ever use a jeep 4.0 in one of these ? I have motor and trans even rear end and I know they have a lot more power the the flatty plus adding a /c would be lots easier . will I still have to move steering ? I also need info on front disc

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did i put this in the wrong place ??????????????

[9 foot box]

   Do a Google search “4.0 Jeep in a 51 Plymouth”. I’ve never read of anyone doing that modification. If I wanted more bang for my buck, I would find a 265” Chrysler Six. It would just about bolt right in. No firewall change needed because of the longer Jeep engine. I won’t go into all the other cons.

[Plymouthy Adams]

cannot answer if in the wrong place, but, you never stated what you are building here.  There is little chance of finding a direct bolt in type engine swap for these old puppies.  For every mod needed you will likely have to do three more mods that affect other parts of the build for the first part to interact correctly.   Your line in the sand on the build will ever be moving.   And while I have done a few swaps I would never try in any manner dictate to another person to follow what I did.  Each of us have our own set of skill, tools and space to work in.  These three are paramount and even with that...I would recommend you set your build down on paper and then NOT stray from the build or make running changes....you will be forever backing up and apt to take the vehicle in a direction that you cannot recover from in means of time, money and function.   For me there is a bit more than just upgrading an engine, chassis mods and braking are two important factors one must address also not to mention added creature comforts.  You will end up wanting the total package.   Also the more modern donor you address the more likely you are going to encounter electronic issues you must be able to adapt.  

Edited March 9 by Plymouthy Adams

[amp56]

I have a 51 and want to use a 4.0 jeep motor but it will have a carb plus I have the complete jeep so I can get rear end with up grades . Not sure about fire wall mods its about the same size as the flatty so I am thinking mounts and maybe linkage

[TodFitch]

  13 hours ago, amp56 said:

I have a 51 and want to use a 4.0 jeep motor but it will have a carb plus I have the complete jeep so I can get rear end with up grades . Not sure about fire wall mods its about the same size as the flatty so I am thinking mounts and maybe linkage

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The 4.0 six that was in my old Cherokee was several inches longer than the Plymouth six engine. There could be lots of cutting to make it fit.

 

If that model Plymouth was also sold in Canada it could have been designed to fit the longer Chrysler block and that would make the job easier. Even there, if I recall correctly, the Jeep engine is longer than the old Chrysler six so it may still require body mods.

[Plymouthy Adams]

as Tod said, length of the engine will come into play quickly here....firewall cuts along with what could well be radiator support relocation and altering even after the fact of moving it forward.  I have done a few of these cars with modern drivetrains.....while very doable, I repeat, none are a bolt in.  As you state you have the Jeep on hand, get out your tape measure and start recording some numbers.  I would recommend a frame clip but that is totally your call there.  The modern suspension will be worth the effort and you will get things like larger disc brakes, massive sway bars, better shocks not to mention power rack and pinion steering along with better geometry and positive caster for the overall better handling.  The total package would be very cost effective.  

Edited 12 hours ago by Plymouthy Adams

[Los_Control]

I personally would suggest a 1951 Ford 239 V8 ... will gain 5 hp and is much shorter then the jeep 6 cylinder. Call me at BR-6549 I can hook ya up!

 

The Jeep 4.0 is a awesome motor and very dependable .... if you can make it work, would be a nice upgrade.

There is a huge following of those motors and all sorts of aftermarket parts available.

 

I can say I saw a Dodge slant 6 installed in a photo on facebook .... it can be done.

Thousands of others have installed 318/360 V8 with enough room for everything to be happy.

 

Free is not always cheap comes to mind here .... just because you have the engine ... it might cost more to install then just purchase a V8.

[Plymouthy Adams]

3 more cubic inches.....210 HP plus a 5 speed OD on the floor....ABS brakes, air bag, full computer driven, zero emission fuel system PDB, PR&P air conditioning...list is complete.....all Mopar....