Motor ideals

[littlejohn]

I was wanting to get anyone opinions on my truck and what you would think be best for it.

Right now i have a 401 amc engine and a 3 speed automatic GM th 400 and a full time warner quadtrac.

What I was wanting to do is to put in a 400 Chevy big block and either GM 700 r4 or a 400 turbo. then i was wanting to put in a NP 205 to a NP 203.

all opinions and informations welcome
thanks john

[64Trvlr]

John
Why not use a 454 instead of the 400, they're the same size and weight? 454/400/205 would be a good strong combo and easy and cheap to get parts for. What's wrong with what you have now? Why do you want to change it out?
:cool:

[ibnfe]

from my experience, big blocks put out too much juice for the front dana 44 axle shafts if you offroad. EVERYONE I know with Jeeps to Broncos to Chebbys with BB motors snap those shafts offroad on a regular basis, mainly the short shaft. Even the alloy shafts from WARN have been snapped a time or two. These are fellas that run 35's and bigger tires though. it would probably be cheaper money wise to beef up/rebuild what you have if the 401 is healthy enough to need minimal or no boring (if it needs a rebuild that is). Just my .02 though.

[UnkleMunky]

If you have low range on your QT, you have a lower low range than a 205 or 203 would give you. I think the 205s and 203s were all in the 2:1 range, where a QT was like 2.58:1 low range. Thus, you'd be giving up some there.

I also have to ask why swap out this combo? An AMC 401/TH400/QT combo is right up there with most everything else you noted, and you already have it in there! Just take care of each of those components and you be all right. Personally, I'd rather hear an AMC engine over a GM anyday. Maybe not as easy to find parts for, but if you already have an AMC(Jeep), why not keep it AMC-powered?

Just my thoughts.....I vote for keeping it AMC-powered, but that's just me! smile.gif Take care...

[littlejohn]

Thanks for your replies

I thought about a 454 but it uses to much gas for me. I'm not totally sure what I m going to do. I thought about rebuilding everything to keep it original but in the long run I think i would be better with a chevy motor because of there durability. I know 401 has cooling problems and Have oil problems when going up inclines.

Actually I dont what to do. I stumped

thanks john

[TimB]

You mention you have cooling problems. A Chevy 400 is not a big block, but a small block with siamezed cylinders, just like the AMC 401, so you would probably have the same cooling problems. A big block would require even more cooling capacity and more space in the engine compartment. The previous remarks about snapping axles with a big block are well worth considering. Also the loss in low range from a NP-205 are not desireable for off-road. My '76 w/AMC 401 also had cooling problems. I had Doug Thorley headers, which increased the problem. I was able to keep it under control with a 4 row high-efficiency radiator and louvering the hood with three rows on each side. This worked okay in Las Vegas, but when I moved to the Pacific Northwest, it was too much water getting on the engine. I would reccomend you find a two row aluminum radiator and keep what you have and use stock cast exhaust manifolds. Yes, Chevy parts are cheaper, but for the time and expense to engineer the switch to all different powertrain will eat up any savings you think you will gain. I am running an aluminum radiator on both my present Jeeps with no cooling problems so far. My experience has shown me that for every modification made, it takes three to four more modifications to make it work. And oh how the days, weeks, months roll by with no Jeep to drive.

[Jake_S]

Why not swap in a Mopar 440. It's the same design as the AMC motors and parts are easy to find and a little cheaper than AMC's, plus, you can rebuild one to stock specs with a slightly bumpier cam,and have all the power you need. I beleive the swap isn't too terribly involved. Just my opinion.
Jake_S

[littlejohn]

I m not trying to argue with anyone but the fact is there are big block they are just hard to find. I have contact alot of people to verify that. thanks for the info thou

[64Trvlr]

Tim
The 400 big block John is refering to is really a 402. The 400 you're thinking of is the small block , as far as the 205 xfer case I run one with no off road problems at all. As far as the expence of swapping drivetrains, if you use all of one make it goes pretty smooth and fairly inexpensive. The real expense is when you mix engines, transmissions, and xfer cases from different sources then it gets expensive fast.
:cool: