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What to do with my motor.

jdub

jdub

Scrambler
Location
Provo, Utah.
Hey, I'm a bit restless with what direction to pursue with my amc258. This motor has a lot of money in it and has served me well for 7 years. I bought my Scrambler used and most all of the motor work was completed. it has:

Original block @ 195,000 today, just turned. (I have had it since 123k)
Mopar's MPI kit. (fuel injection, resembling the 4.0)
Throttle body spacer that really helps on the hills.
Headers.
Serpentine belt system.
A/C.
Alum. valve cover.

I'm very interested in keeping the same set-up in my jeep for reasons of all of the performance parts and feel. This vehicle is amazing. I wheeled late last night, and this morning drove 75mph on the freeway to go shopping and Mtb in SLC while getting close to 20mpg with 35 ssr's

I have another Cj with a SBC swap that I love for the power but it doesn't have the OEM feel like my Scrambler. I don't really want to mess up the value or original feel that this rig has.

I was thinking of doing a bore and rebuild and keeping it the way it is forever. I want a little more power though so I was thinking of getting a stroker type build or swap out this block for a new one.

Either way it will cost big bucks, I've decided that a rebuild is the most affordable and satisfying(less headache) But is there something that I am missing? Is there a factor that I should look at? I don't want to back paddle with a carb. I love them but for climbing hills they aren't any fun. I've heard of headaches from doing a tbi sbc swap. Any ideas will help.

Thanks guys.
 

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M

Meat_

Banned
Location
Lehi
IMHO, if you are going to change anything from stock you just as well put a tbi sbc in it.

Motor/parts/+HP/performance are all cheaper and more readily available. And the motor weighs less.
 
jdub

jdub

Scrambler
Location
Provo, Utah.
I've heard it both ways, people putting heads form a 258 on a 4.0. Can you do it visa versa?

If I did a Chevy transplant I'd run into some motor swap issues that I just love to deal with and at 1985 I think it becomes harder than my '83 is as far as the rule books go. I've been told otherwise though, just as long as it has all the current smog it's fine, as well as being offered in the same class of vehicle.

I don't want to create more of a headache than I need to when emissions comes up every year.

My current issue with a chevy swap is the clearance-ing of the tranny pan and the front driveline with my other jeep.

But the SBC in a Jeep is so much fun to drive. My wife can't drive stick(mentally) and it would be a great upgrade.

Other things to look at in the swap:
Drivelines.
Radiator
Motor mounts
Exhaust
Adaptor from TH350 to d300
All these need to be factored into the price 'cause the purchase of a donor car is the easy part.

Any thing else i'm missing?
 
DaveB

DaveB

Long Jeep Fan
Location
Holladay, Utah
jdub said:
I've heard it both ways, people putting heads form a 258 on a 4.0. Can you do it visa versa?

From what I have seen people usually take a 4.0 block and head and use the crank from the 258. The 4.0 bolts up just fine and uses the same motor mounts as the 258.
Click to expand...
 
DaveB

DaveB

Long Jeep Fan
Location
Holladay, Utah
jdub said:
THank's DaveB. Have you thought a SBC?
Click to expand...

I am going to put one in my 73 Commando project, however emissions requirements are easier to meet on a 73 than your 85. I know you can swap to a v8 in your newer Jeep if you go with a motor that is newer and you put all of the smog stuff on it. When I called the county smog boys I was told that if I did change the engine in a rig that was 84 or newer I would have to have the county do the smog test every year. I put a 99 motor in my 84 CJ8 and the guys that inspect and test it every year don't seem to have an issue with it. The first year I took it in they tested it over and over again because they couldn't believe how low the numbers were for an old jeep.
 
T

Toad

Well-Known Member
Location
Millville(logan)
Put a sbc chevy in it. Oh when your done shot me your address and I will come take that fuel injection of your hands. I really like my 4.2 I have a Weber on mine. The only time I wish I had more power was deep snow or mud. What axle ratio are you running?
T5 has overdrive th350 does not.
 
jdub

jdub

Scrambler
Location
Provo, Utah.
Man, This isn't a very easy choice. I got a bare minimum estimate at 3k for a rebuild. Makes me want to do it myself except I'd pay 3k for a warranty on the work. It's not bad, but has anyone found a better price?
 
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