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Easiest way to boost performance on stock 258?

The "right" gearing depends on your type of driving. How high do you want to rev it in high gear for extended periods if you use it on the highway? Isn't the T-5 overdrive in high gear? If it is, it would allow you to run steeper gears and not over rev the engine.
I have an '81 with stock 258 with the HEI upgrade and stock BBD carb. It starts and runs perfectly. I have the stock 273 gears. I do some fairly long trips so they work for me. The engine runs about 2200 RPM at about 68 MPH. I can cruise all day long at 65-70 and get an honest 17 MPG. I would like steeper gears but don't feel comfortable revving it much higher on the highway. I use low range when I am off road and get by. My opinion is do the distributor upgrade and get a carb if your stock one doesn't work. Get rid of the smog stuff if you can, make sure it is tuned properly and enjoy it. If you want something to set you back in the seat and pull a load, go with a V-8.
 
Don't be afraid of the electronics and the 5.3L/5.7L or the 6.0L EFI engines. I was but I'm so glad I got over it. I even have the 4L60E electronic transmission. Basically once you have the harness in place all you need from the Jeep is a 12 volt power feed.
 
Check another thread here for everything you need for $750 right now
 
Not trying to hijack the OP.
Maybe not easiest, but what is everyone's thoughts on a stroker?
Anyone with experience with one?
 
FLCJ8 said:
Not trying to hijack the OP.
Maybe not easiest, but what is everyone's thoughts on a stroker?
Anyone with experience with one?
Click to expand...
I looked into it but I didn't think there was enough power increase to justify the cost.
 
I am curious, how fast do y'all want to drive pulling how much weight :shrug:

My two regular long distance drivers:

1) Red (258/Mopar MPI/AX15/33" tires/4.10 gears) - this one is "heavy", i.e. bumper/tire carrier/rock rails/in cab cage, this one drives 75-80 mph all day long, 17mpg. On steep/long grades, down shift to 4th gear, maybe lose 5mph.

2) Tan (350/TBI/700R4/33" tires/4.10 gears) - this one is light, no bumpers/armour/cages/tire carriers. This one I run the same speeds as the 6 cylinder one, 75-80mph, 14mpg. The V8 does have more power at higher speeds, easier to pass, does not take as much throttle/down shifts to maintain speeds on long grades.

Just my opinion, but 75-80 is about as fast as I want to drive a lifted (or stock) CJ for any length of time. Just my opinion, but these things were never designed/engineered to be cruising 90+mph all day long. That being said, I did drive the tan one in South Dakota at 90mph for a good chunk, BUT this was on a very good condition 4 lane interstate where the speed limit was 80MPH. Much past 90, starts feeling really light/twitchy :twocents:

My 6 cylinder pulls my small/light trailer fine, BUT the V8 is noticable, since I have the choice, I grab this one for trailer pulling. The most weight I have pulled, and it was definitely overloaded, 2 cubic yards of dirt out of the big Caterpillar front end loader, about 4,000 pounds. The 6 cylinder pulls fine, V8 does better. That being said, that is too much weight to be pulling with a CJ :twocents: After 20 trips, the trailers rear axle bent (1,200 pound axle), and the front tongue folded :crazy: With that much weight, using the V8, I did not use overdrive. Big no-no to pulling heavy loads with a 4L60 in over drive:twocents: So, I was cruising around 55-60 MPH.

On closer to stock Jeeps, my experiences:

My green one (30" tires/3.31 gears/T5/stock 258 with feedback Carter and all systems working) - this one feels the "weakest" at high speeds, but it cruises fine at 65-70MPH. The "weakness" could be the 130,000 miles on the engine.

Tommy's Green Yard Scrambler (32" tires/3.31 gears/T176/fresh 258 with non-feedback Carter) - 70-75MPH no problems, felt good and strong

Josh's Tan Scrambler (P235's/stock auto trans/2.73 gears/stock 258 with Motorcraft carb) - 65MPH in this one felt great, and good mileage. Small tires with 2.73 gears is the key.

Colorado Jamboree (P235's/T5/completely stock 258 with 82 emissions/3.31 gears) - only 50k miles on this one, it ran 70-75 MPH from Colorado to Louisiana no problems, felt strong, good mileage.


The biggest key, IMO, keep the gears and tires right, keep the engine you have running at its peak, these things drive fine on the interstate :twocents:

Obviously, the big V8's are "quicker", but you can hang with them on the Interstate, and pass them when they are at the pump :twocents:

The other issue, my TBI 350 is rated at like only 200HP/300 pound feet of torque. Even with Warn Full Float axles/Detroit Locker, I am not sure how much more power I would want to be pushing through an AMC 20/Dana 30. If your like me, if it has the power, I am going to use it :twocents:
 
Yes it is DeLuke! Ha Ha small world. Damn dude, you own a lot of jeeps! I don't wanna post my cell on this ;public page but send me a PM and I'll hit you back with it. burs
 
hey, thank you for all of that info. I'd grade myself a "c" mechanic so admittedly there are a lot of things I do not know. What exactly is a "4.0HO head"? Is this something I can do on my own in the garage? sorry for all of the questions…cb
 
CBurson said:
hey, thank you for all of that info. I'd grade myself a "c" mechanic so admittedly there are a lot of things I do not know. What exactly is a "4.0HO head"? Is this something I can do on my own in the garage? sorry for all of the questions…cb
Click to expand...

You replace your head with a 4.0 High Output head from a fuel injected cherokee or YJ. You can keep your stock intake and carb, but you have to get a different exhaust manifold/ header.

The 4.0 head offers a lot better flow than the 4.2 head, so it has a lot more power.

It does require removing quite a bit though, and won't be cheap.

http://offroad-review.com/new/index.php?page=68
 
The thread linked doesn't explain filling those holes. What's that all about?
 
The 4.0 has more water passages than the 258. You can bolt a 4.0 head on a 258 without plugging the holes, but eventually it leaks through the gasket.
 
tower210 said:
Here is a post that shows how and which holes to fill.

https://www.jeepstrokers.com/forum/viewtopic.php?t=24

I'm not sure if you are looking for a little more power; that dropping in a healthy (but not beastly) 350 isn't about the same amount of work, and may be a "simpler" task......
Click to expand...

That all falls into Vehicle Modification over here and is quite simply a PITA, replacing the head,not so much.
 
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