How fast will a CJ with a 258 go.

[ryankopecki]

1040190

I have a CJ-8 with a 5" lift, 33" radial buckshot mudders, 3.31 gears, a t-4, and a rebuilt 258 with headers and a weber. The fastest I've got it to is 58 mph on flat highway. I think maybe I need a bigger jet for the secondary side of the carb but I want to know what I should expect. Please list the engine size and mods, lift, tires, gears, and trans if you can.
[addsig]

 

[synergy]

1040196

well the fastest i go in my jeep is around 83mph with 273 gears and 31's i am in fourth gear then fifth is useless unless i regear my axles.
[addsig]

 

[sillsmack]

1040219

Ryan,

Check a couple of things :

1> look and make sure you don't have something under the go pedal like
a scrunched up carpet or mat
OR
lots of sand & rocks
OR
a dead badger, ect...

2>verify the throttle is in fact going to full throttle.
Get a pretty girl to sit in the captains chair and stand
on the go pedal all the way to the metal. While she does
this you pop the hood & remove the air cleaner and see if
the throttle will open anymore.

If all this checks out, geez dude, maybe it's time to go to the
wrecking yard and look at GM 350V8's...





[addsig]

 

[jsharifi]

1040224

I have an 85 CJ-7 with 31's, 258 and a t-5 transmission. I'm not sure what the gear ratios are (although I would bet that they are between 2.73 and 3.31), but I've taken it up to about 75 mph once or twice. I'm sure I could push it a little more... but since my CJ is about as aerodynamic as a barn door I tend to not want to take it on the highway and test its limits.

It sounds to me like you need to re-gear so that you have more usable power. Even in my CJ fifth gear is just about useless with 31's on.

Good Luck,
Jim
85 CJ
[addsig]

 

[ryankopecki]

1040233

I have the t-4, no overdrive. The throttle opens all the way. 3.31 with 33s is lower than 2.73 with 31s. Most jeeps came with 2.73, I was just lucky to have the lower ones. And i'm thinking of an AMC 390 or 401 for when I swap engines. But that's not untill after the Dana 44s, lockers, 4.10 gears and 38" tires show up in a few years. The 258 is freshly rebuilt but I did it cheap so that it won't too last long and it will give me a good reason to put in a new motor. Hows that for planning ahead.
[addsig]

 

[jackal]

1040251

I have a 78 with a 232. It has a 258 2bblcarb and intake. the gears are 3.54 , and it tops out at 60 mph on level highway.

Jackal
[addsig]

 

[tangel]

1040345

I have an '86 CJ-7 258, Weber 32/36, GM HEI, T-5, 3.31 with 33's and a Maryland state policman got me going 85 down I-95 on level ground. That was about where it tops off unless Im goin downhill with a tailwind.
[addsig]

 

[jprtroy]

1040536

Heck, my 82' CJ-5 with T-18, 4:10's, 33's, Mopar multi-port kit goes faster that. Not much faster though! 62 -64MPH is all I can get out of her. Gearing is the reason in my case. Are you positive the gears are what you mantioned? When I had her stock (3:31's with 31's) I could get 75-80 no problem. A little on the squirley side at that speed, but she'd do it.[addsig]