swapping engines

Hi im planning to swap a Chevy 327 small block into a 68 jeepster commando and im trying to come up with a list of the things that need to be changed or modified.So far i know i need a new trans and im pretty sure the gm th400 matches the dana 20 t-case with no adapters,and i think i need to get rid of the ross steering box,and new motor mounts.thats all i know so far,but please correct me if im wrong and all other responses are welcome.Oh and it has a 225 Buick.

 

You will need to trim the radiator suport back, and move the rradiator foreward most likely.
also, the front cross member will most likely need to be modified as well.

A previous owner had droped an AMC 304 V8 into mine at some point, they did a prety good job actually, but it has no radiator suport any longer, no safty hood latch, no engine powered fan (they used and electric) and the radiator is mounted 2" behind the gril with the fam snadwiched in between, the front cross member is notched out to clear the crank pully on the engine
its a bit scary to drive on the highway with no secondary hood latch and only the spring loaded hood pull downs on it (i'll be changing that)
they did leave the Ross steering box, but the exhaust manifold just misses it.

You will need an adapter for the Dana 20 t-case to the TH400. The Dana 20 uses the 'Texas' bolt pattern and the TH400 is circular if I remember correctly. there is a factory adapter available, but its weaker than the aftermarket adpates like the one Novak sells.
If you dont already have the Dana 20 T-case adpater for the TH400, you may want to consider using the Dana300 t-case, it is a stronger case and a stronger adpater.


If you do get rid of the ross stering and use a saginaw box, you may want to use a '72-'73 steering column with the column shifter on it. Adapting it to the steering shaft may be easier

while your in there, be sure to replace and upgrade the wiring under the dash and in the engine comparment. Mine was/is a mess and I am still working on it, I have found several wires with melted insulation and arcing to the chassis.


Hope that helps some.
Good luck and please post up pictures.

 

thanks for the info, but i came across a good deal for a sm465 and i was wondering what t-case will match up without a adapter if any,and i figured the radiator had to be moved forward so thanks for confirming that.

 

NP205, NP208 have factory adapters to the SM465.
I'd use the NP205 myself, if you look hard enough, you will find the factory 'Short' adapter that is only 4" or so long.

I will be running the SM465/NP205 in mine unless I decide to stay with my TH400.

 

I would worry that the NP205 is too wide to fit between the frame rails in a CJ or Commando. The 205 also does not have a very good low range gear, and they are anchor heavy.

I'd stay with the TH400, and swap in a Buick V8. The SBC is easy to find and parts are cheap, but the 300/340/350 Buick is a great swap into a V6/TH400 Jeepster. Move the radiator forward and it drops in, no other mods. The Buicks are smooth, long-stroke torquey engines too; great for Jeeps.

 

i would put a buick 350 but i didnt get one of those for free,and i really want a standard transmission instead of the th400 but im trying to find a t-case or a cheap adapter for dana 20

 

I agree on the Buick engine as well.

As for the NP205, gears are available for it. They are heavy but darn near indestructable to.
T-case selection depends alot on what you are doing with it offroad.
You could also get an adapter for Dana300 t-case to the SM465, (Novak makes one for that).
It is alot lighter and does have a slightly better ratio in stock trim.

He asked for a t-case that would mate to the SM465, the 205 and 208 are the factory t-cases. Anything else requires an adapter.
The 205 is a gear driven t-case, the 208 is chain, I perfere gears is all, that why I would use it.

The SM465 has a wonderfull first gear (6.65:!), and that does help make up for ratio on the 205.

 

i think im going to try and get a sm465 and a 205.so far from research its cheaper to get a used 205 instead of a adapter for a dana 20 or 300

 

I've seen guys use the NP205 and notch the frame, not sure if it will actually fit. I know the Rockwell T221 transfer case fits because I had one behind my SM465. I wouldn't recommend them, they haven't been built since the mid 60's, and some say the upper bearings starve for oil on the highway. If my Jeepster was off road only I would have continued to use it. They weigh close to 200 lbs like the NP205.

 

Not to pile on ... but a couple of comments.

- Most of the strength of a ladder frame is in the frame rails (horizontal part, top and bottom), not in the web (vertical part). The web just holds the rails in place, and the rails are in tension and compression to support the weight of the vehicle. Notching the frame rails will compromise frame strength a lot. You'll need some additional reinforcement to achieve the original strength, and then you get into a mess of where to reinforce, flex versus stiffness, stress risers... a mess. IMO you should go way out of your way to avoid notching the frame rails.

- The old saw says "having the engine does not a good swap make." It'll be cheaper in the long run to use the engine that's the best fit to the vehicle, whether you have it on hand or not.

- Add front disk brakes, put a shift kit in that TH400, and you might like it. The TH400 is very strong and very durable. Think long and hard about discarding the great transmission you already have for something different. Also, the manual-to-automatic swap is much easier than the automatic-to-manual swap. You have to add a lot more stuff to accommodate a stick... mostly you remove stuff to accommodate an automatic.

Also, in case you didn't know, you use a different two-footed driving style with an automatic in the rocks. One foot on the brake and one on the gas - power up and ease off the brake to climb an obstacle. The pro crawlers use automatics ... they work.

 

thanks for the info but im pretty set on the 327 and my BOP trans does not match the gm style bellhousing so either way i have to get another trans.And im prepared for how much work it will be to put this motor and trans in.im going to try my best not to notch the frame and if i have to ill have to break in my fabricating skills.another question what t-case goes on a sm420 with no adapters?

 

never mind about the sm420 they are only divorce mounted with no adapters

 

Jegs and Summit sell an adapter plate to use a BOP trans with Chevy and vice-versa. Likely the easiest route, if you are set on the SBC. New frame towers, move the radiator forward... Buick is easier, but the SBC should fit ok.
http://www.summitracing.com/parts/TCI-230001?part=TCI-230001&autoview=sku

 

thanks

 

sm420 can easily be adapted to your d20 or d300 with a kit from Advance Adapters or Novak adapters. Both have the option of using a stub shaft or new longer main shaft that requires tare down of the trans. Kits are about 400 to 500 depending on where you get them. You would have to have a car style or original sm420 chevy bellhousing with the smaller hole instead of the larger sm465 truck style. I am doing this swap on my SBB350 - sm420 - D20 as soon as the trans syncro kit I ordered shows up.