Motor Swap

[Dog_run_720]

I'm currently doing some research on motor swaps for my 84 720. I'm torn between 3 motors and would like the opinion of the community on which may be best.

 

I bought the truck as a project for everyday/offroad use. The z24 is tired and needs a complete rebuild. Its already lifted and running 32's on 15" wheels. It is a factory 4wd manual transmission. 

 

The motor ideas I had are a ka24de, a Cummins 4bt or small block 305 tpi. I'm aware that all of these motors will require some extent of fabrication with the v8 requiring the most. 

 

I also plan on doing a sas and snorkel if that helps to. So what says the community?

[datzenmike]

Ahhh an engine swap.

 

Go with the KA24DE from a D21 Hardbody. First it fits, (oil pan) second you don't need to replace the transmission and alter the driveshaft length, third the exhaust and intakes are on the same sides, forth ]2eDeYe, a member on here, makes engine brackets to make this work.

[Dog_run_720]

Now with doing a sas, is oil pan fitment a big factor in the motor swap? I was thinking a dana 44. Probably a 60".

[]2eDeYe]

The KA will bolt up to your existing transmission. Any other option will require more drivetrain components. 

 

You still want rear sump to keep the axle path clear, whichever motor you choose, if you are going to SAS. 

 

You can run a wagoneer 44 or a yota front axle and be at about the same track width as stock. They are slightly wider than 60"

 

 

 

[weldingrod]

Friend of mine put a 302 into a Mazda pickup years ago. Massive firewall alteration but he got it in. Problem that arose was overheating and after trying every remedy it still overheated. He was about at the end of his rope when I asked him why doesn't he block the hinges up so there would be about 1 1/2" gap between hood and cowling. It worked.

[Lockleaf]

Unless there is already a bunch of work on the 305, just do a 350 if you go that route.  305 bump in power over a ka24de is not enough to justify the immense effort of installing it.

 

I was looking into an OM617 swap for my 720 for a while.  5 cylinder 3.0L turbo diesel from Mercedes Benz.  Low powered stock but takes mods quite well, much like the 4bt.  Lost interest in diesel before moving forward.

[datzenmike]

SBCs are boat anchors. Truck would be ok in a straight line but would need massive disc brakes and suspension work and then it still would never handle like a 4 cylinder.  

[Dog_run_720]

To be honest, I really want to do a straight 6...but I dont have the money for that kind of project. Nor have I found a motor that would be a close fit.

[datzenmike]

I measured up a 305 years ago for my '78... it doesn't fit.  Or would fit without a rad. A 3.8 chevy V6 would but again, heavy.

 

Inline 6s are even worse for length. 

[bottomwatcher]

Look in the how to section for the ka swap. I have a ka24e in my 82 with 31s it is no powerhouse but will keep up with modern traffic unlike the original z motor. I can actually pass someone now on a two lane without 3 miles of planning. If you start throwing major power at the original drive train it will not hold up. The SAS will release a lot of the oilpan clearance issues. A stock ka will not drop into a 720 without serious oilpan work.

[datzenmike]

Going from 28 " tires to 32" tires is killing your acceleration. Your 4x4 will have 4.11 differentials. By going to 32" tires your overall gear ratio has been lowered to 3.59. 

 

Find an '80  Long Bed 4wd and swap the H-190 and R-180 differentials. The earlier ones were 4.625. This will almost perfectly cancel out the taller tires, bring back your acceleration and the speedometer will read correctly again.

[Dog_run_720]

The speedometer is another issue all together. Doesnt work at all. I use a gps app to give me a rough estimate. The area in which I live is what pushes me to the bigger motors. I live in the foothills of northern Idaho. The truck needs plenty of torque and a fair amount of whp to boot. Between 200 and 250 hp is what Im shooting for. Between 200 and 300 lbft as well

[weldingrod]

Has anybody thought of a 3 cylinder Yanmar diesel? Small, lots of torque.

[bottomwatcher]

Chevy 4.3 with matching 5 speed would be most cost effective with lots of support for power gains. There were swap engine mounts available at on time. Hope you are good with a welder and have deep pockets because swapping isn't cheap.

[nl320what]

My vote is for the KA Swap.... 4BT would be $3000 alone plus adapting fabrication labor/time.

 

In the meantime spend about $500 and get the Z24 head checked/rebuilt and install a std ring kit in it.

 

Gets your power back and on the road while collecting stuff for the KA swap or whichever you decide.

 

[Lockleaf]

On 11/11/2018 at 7:27 PM, Dog_run_720 said:

To be honest, I really want to do a straight 6...but I dont have the money for that kind of project. Nor have I found a motor that would be a close fit.

You talking RB or JZ?  It's been done in a 720 but you need cooling to be in the bed.  Doesn't seem worth it in a 4x4.  

[Dog_run_720]

12 hours ago, Lockleaf said:

You talking RB or JZ?  It's been done in a 720 but you need cooling to be in the bed.  Doesn't seem worth it in a 4x4.  

I was actually thinking bigger. Like the Atlas 4200. The other idea was the ford 300...but that would have to go in the bed.

[Dog_run_720]

On 11/12/2018 at 3:47 AM, bottomwatcher said:

Chevy 4.3 with matching 5 speed would be most cost effective with lots of support for power gains. There were swap engine mounts available at on time. Hope you are good with a welder and have deep pockets because swapping isn't cheap.

I have help in the welding department because I suck at it. Most of what Im looking to do is gonna come from a junkyard and I will rebuild as necessary.

[Dog_run_720]

On 11/12/2018 at 4:56 AM, nl320what said:

My vote is for the KA Swap.... 4BT would be $3000 alone plus adapting fabrication labor/time.

 

In the meantime spend about $500 and get the Z24 head checked/rebuilt and install a std ring kit in it.

 

Gets your power back and on the road while collecting stuff for the KA swap or whichever you decide.

 

Thats what I discovered. Found a guy selling a 4bt and Eaton 5 speed for $3500.

[datzenmike]

200+ hp??? well that really limits you. Forget the KA. 

[nl320what]

They are awesome little powerhouses if you have the cash I would buy it, cause you can always resell it easily if it dont work out.

 

They were in UPS and Bread Step Vans.

 

I'm in the crawler scene alot, so the 4BT is one, the OM617 Benz diesel is cheap and popular, also seen a couple Perkins Desiel swaps.

 

In the interest of getting it on the road faster and economically, head and ring job the Z24 cause they last over 200,000, but the heads tend to get cracks, have it dye checked.

 

[Dog_run_720]

So update on this. Found a rolled 83 and pulled the head to swap it over. Which turned out to be a good thing. The head on the 84 had a crackin the camshaft support and the head gasket was blown on the driver side of the number 3 cylinder. Have yet to find an axle for a SAS. Gonna see if I can salvage the pieces I need. Does anyone have a good site for front suspension pieces?

[Stoffregen Motorsports]

http://www.car-part.com/

[Lockleaf]

Www.craigslist.com

[]2eDeYe]

row52.com