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4.2 with 4.0 head or stroker?

tower210

Scrambler Junkie
Lifetime Member
City
Olathe
State
KS
Will it hold speed on the highway? I don't care about power above 4k rpms. I just want to make good and sure that I have enough power to go down the highway.

My stock 4.0/4.56 gears/ 295/70/17 will do 75 on the highway.....not much more; but I fell that’s plenty. I ride 90 minutes each way to my local orp.... little rough with mud caked wheels on the way home
 

CJ-8_Jim

Scrambler Junkie
Lifetime Member
City
NW Chicago Suburb
State
IL
Will it hold speed on the highway? I don't care about power above 4k rpms. I just want to make good and sure that I have enough power to go down the highway.

With 2.73 gears and 31s I easily do the legal max highway speed... I never go over the limit, so I wouldn't know what my budget stroker can comfortably cruise at above that. :unsure:
 
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BDCCLARK

Active member
Lifetime Member
City
gravois mills
State
MO
I'm not worried so much about top speed. I just don't appreciate under powered engines. The whole idea seems like an engineering mistake to me. I want to make sure my jeep will hold highway speeds in overdrive. Heck, I wouldn't even bother messing with a swap if I knew a 258 would do it. From what I read, I'm not so sure it won't. It seems to me that one of the major drawbacks to a solid running 258 is the stock ignition curve in the distributor. I see many people putting efi on and love the improvement in power and drivability. I'm betting that it has way more to do with the computer controlled spark curve.
 

YJ-8

Basic User
City
Austin
State
TX
Will it hold speed on the highway? I don't care about power above 4k rpms. I just want to make good and sure that I have enough power to go down the highway.

Yes, when I had 31" tires and 3.73 gears it had no problem holding speed, it is solid. 5 speed manual, you could chirp the tires shifting 1-2 and once I chirped it going into 3. It will hold 70 no problem, it will hit 80, but its happy place is 30-60, so IDK how fast it will technically go. Fastest I ever hit in it was 95 mph (stock engine) and did not find it very fun, its a Jeep.

Now that I have 35's with the same 3.73 it has trouble on long mountain passes.

FYI: when it was stock (carter BBD carb) it could not hold highway speed if the wind was blowing against you, it was a dog.

All this said, its no modern V8. I drove a 6.0 Caddy Escalade and it would hold 80 up a mtn pass like it was flat, and that weighs 2,000lbs more than my Jeep. It would be nice in a CJ.
 

BDCCLARK

Active member
Lifetime Member
City
gravois mills
State
MO
Yes, when I had 31" tires and 3.73 gears it had no problem holding speed, it is solid. 5 speed manual, you could chirp the tires shifting 1-2 and once I chirped it going into 3. It will hold 70 no problem, it will hit 80, but its happy place is 30-60, so IDK how fast it will technically go. Fastest I ever hit in it was 95 mph (stock engine) and did not find it very fun, its a Jeep.

Now that I have 35's with the same 3.73 it has trouble on long mountain passes.

FYI: when it was stock (carter BBD carb) it could not hold highway speed if the wind was blowing against you, it was a dog.

All this said, its no modern V8. I drove a 6.0 Caddy Escalade and it would hold 80 up a mtn pass like it was flat, and that weighs 2,000lbs more than my Jeep. It would be nice in a CJ.

Thanks for the reply YJ-8. I'm gonna give the inline 6 a whirl. The higher rpm engines are great for sure, but I love the low end pulling 6s.
Chris
 

YJ-8

Basic User
City
Austin
State
TX
Thanks for the reply YJ-8. I'm gonna give the inline 6 a whirl. The higher rpm engines are great for sure, but I love the low end pulling 6s.
Chris


I think you will be impressed how stout a good running I-6 can be, It can surprise you. I also think they have charm.
You can PM me and I will give you all the specs I have on mine.

YJ-8
 

BDCCLARK

Active member
Lifetime Member
City
gravois mills
State
MO
I would love a full spec rundown. I don't seem to have the ability to pm you though. Chris
 

Dave The Sparky

Rebuilding my CJ8 very,very slowly...
Member
City
Halifax
State
UK
I would love a full spec rundown. I don't seem to have the ability to pm you though. Chris

Hover your mouse over YJ-8s avatar and then click start conversation when the information box appears.
Or click on his avatar and the start conversation button should be there..
 

BDCCLARK

Active member
Lifetime Member
City
gravois mills
State
MO
I think you will be impressed how stout a good running I-6 can be, It can surprise you. I also think they have charm.
You can PM me and I will give you all the specs I have on mine.

YJ-8

message sent
 
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