Re: CJ 258 top end
Do you have a tachometer? What kind of revs are you turning at 60-70mph ...I'm figuring 2700-2800 with the specs on tires & gears you listed. -Anyways that is where it just starts delivering the ponies right? I'm no expert on the ole I6, but I know that mine likes to sit at about 2400-2600 running on the highway turning 31s with 3.31gears and it delivers just enough to stay at speed up these long hills in the Carolinas. Now that TFI and ignition upgrade will help you get a good burn out of her but I don't know about getting many more ponies out of her after that for the highway. I guess it depends on what kind of rpms you are comfortable running at, mine will sing to 3800 ...but she makes me ease up for fear of throwing a rod or loosing a valve - so I rarely take it past 3300. (Not to mention that after about 85mph, she feels more like a watercraft than a Jeep) Anyways, just thought I'd give you my ideas. Later.
'84 CJ7 258 w/HEI