v8 Swap

[That_Creepy_Guy_In_The_MJ]

Alrighty fellas! Good news! I've got a 350 bored to 355 small block, and I'm wondering if I'm missing anything from my grocery list, here it is.

350 small block

SM 420 4 speed transmission

Transfer case Np231 for torquey handling

Efi to carb conversion kit

PCM

V8 mounting brackets and the like

Power train wiring harness

V8 Radiator and cooling system that can fit into the small jeep grille

Run the Jeep ECM computer with the GM powertrain computer. OR convert the gauge cluster to something GM compatible

Remember make the engine think it’s in a GM vehicle!(Principle)

Fuel delivery system can be retained with the stock tank, however you’ll have to fill it up more often XD

Lift the truck before any of the actual swapping begins, because it will clear the way for the engine then stock riding height.

 

 

 

[schardein]

EFI to carb conversion kit?

 

What engine do you have?  And if it was equipped with fuel injection, I highly recommend doing whatever is necessary to retain it.  

 

I've rebuilt and tuned carbs.  I don't miss doing it.  FI is the way to go.

 

I have no experience putting a V8 in an XJ/MJ, but generally speaking, two things that always complicate an engine swap for me are power steering lines and exhaust.

[DirtyComanche]

Do you like driving a SM420?  I hated driving a SM465 truck and went with a NV4500 in my Cheby.  I'm not sure if you can easily bolt a NP231 to a SM420 either?  I guess adapters are probably available.

 

Pretty certain AA and Novak both make motor mounts.

 

What year is your truck again?  Renix ones don't have a PCM.  I don't even know if the OBD-1 HO trucks really have one either.

 

I'm assuming you meant a carb to EFI conversion.  What system?  If you get a standalone TBI setup (lots out there, Edlebrock comes to mind) you don't need much to run it, just swap in some included sensors and their distributor.

[That_Creepy_Guy_In_The_MJ]

Mine is an 88, and I was gonna go efi to carb because well, I hate carbs but it'd be cheaper.

[That_Creepy_Guy_In_The_MJ]

And my jeep is an inline 4.

[johnj92131]

Mine is an 88, and I was gonna go efi to carb because well, I hate carbs but it'd be cheaper.

 

Cheaper is not always better in the longer term.  Frankly, even if it is cheaper - you are being penny wise and Pound foolish (IMHO).

 

EFI is such a huge performance improvement over carbs - you will spend way more trying to get carbs to run well than you ever will to get an EFI system installed and running correctly.  Case in point:

 

My son- in- law still has his first car - a 1964 Chevy SS.  During the complete restoration, he and his dad put in a rebuilt 350 with all new parts from the carb to the exhaust.  After a couple of years trying to get the 4 bbl carb properly set up and the car still running poorly, he took it to a dyno shop for a proper tune.  Results, needed a different carb, new intake and several hours of dyno tuning and rejetting.  His final cost  was over $1100.  But the car now idles properly and runs properly at sea level, Unfortunately when he takes it to the local mountains for a car show, the car will not be running as well at 4000 feet.  He could have saved that $1100 to do the engine properly with a later EFI engine.

For him, it was important to use the period correct carb for 64 Chevelle and to use the 327 block he had for the car. I have no problem with that at all.  But he did take my suggestion to use a 4 speed automatic in place of the original 2 speed Powerglide.  It makes for a much quieter running car on the freeway.

 

For your 4 cylinder truck - consider getting a full aluminum block Chevy truck engine and a set of factory aluminum heads.  That will cut the weight of the engine way down - to the point you will be able to retain most of the front suspension from your 4 cylinder Jeep.  Consider that if you go with a cheaper, all iron Chevy engine you will have to spend a bunch of money to upgrade the front end of your Comanche.  So when you consider total cost - it is the same to use the all aluminum engine - even if the engine costs more up front.  Same logic to buying an EFI engine.  Yes up front it may cost more.  But then you have to spend the $1100 (or more) to correctly set up the carb. 

 

See why it is cheaper in the long run to go with the EFI aluminum V8?

[DirtyComanche]

Running modern (LSx) GM truck engines can be had with the harness and computer for $1000~ if you look around, which will at least get you a modern engine with aluminum heads.  Not much more to include the trans and tcase.  Dollar for HP the swap tends to make a lot of sense.  Expect to spend time (and money) making the cooling system happy.

 

While a carb'd SBC is cheap swap compared to more exotic engines, the numbers just don't add up to me.  You're better off buying a $500 Renix era 4L XJ and pulling everything out of it, as basically it's a bolt in swap with extremely minimal screwing around fabbing parts or modding wiring (fuel pump/sender is still an issue, but can be solved easily enough, and the rear driveshaft will need work).  Power output from the 4L is comparable to an early carb'd 350, assuming the 350 is a nothing special stock everything.

 

Even to swap in a carb'd 350 will wind up costing a fair whack of money, by the time you get the cooling system solved, motor mounts, trans mount/crossmember, adapters for the trans or tcase, new driveshafts, wiring, changes to the fuel system, engine accessories/hoses.  Unless you just go king bojang on it and use whatever is lying around the farm.  Also, if you go with a non-OD tranny (SM420), expect a hit in fuel economy, although fuel economy is a laughable concept with a carb'd 350 anyways.

[husky410ohio]

I have a 350 with holly carb and SM465.  You can look at my build in the forum.

[That_Creepy_Guy_In_The_MJ]

I have a 350 with holly carb and SM465.  You can look at my build in the forum.

Sweet thanks! Super helpful!

[Nodrama43]

seriously considering a GM v8 swap into my 91.....

 

looks like a pretty serious undertaking though.

[Tex06]

If you wanna carb it, go for it. I recently swapped in a 355 in place of an oddfire V6 into a Buick Skylark. Went with carbs because it's cheaper (yes, even in the long run) and they're easy to work on. Most likely you have a mild built motor and a 600-650 cfm carb is all you need. The most common issue people have with sbc motors is over carbing and over camming them. If you're unsure, get as much info about the motor as you can (cam specs, displacement, valve sizes, head volume, intake type, piston type) and go to your local speed shop or hot rod builder. Offer to take the oldest mechanic there to lunch in exchange for advice on your motor. Lay it all out and see what he recommends.

 

 

 

Carbs, like anything else get real expensive when you don't know what you're doing. I recommend edelbrock because they're super easy to rebuild and tune. Not as efficient as holley or quadrajet but easier to deal with and more forgiving to mistakes.

Sent from my SM-G930T using Tapatalk

[zomeizter]

For all the involved work, blood, sweat and tears with your upcoming swap, I would definitely recommend injection even if it's TBI. LSx would definitely be the way to go for your power swap but since you already have what you have, by all means install that, it will make it easy to upgrade in the future to the efficient LS you really need...you got this!