67' CJ Top Speed?

I just purchased a 67' CJ project. It currently has the F-134 engine and I was curious what I could expect for a top cruising speed?

 

From what these guys have told me, if your stock pretty much bet on like was said 45-65 mph. I personnally keep an eye on the tach. I don't go over 2800 to 3000 rpm's regardless of speed or gear I'm in.
Some will say 3500 but I feel higher rpm's = more wear.

And you will definitly notice a difference on windy days, I can maintain 55 mph on a calm day but if I'm drivin into the wind like yesterday around 15 to 20 mph wind I was at around 48mph floored.

 

With 5.38s I can squeeze 55mph downhill outa the Hurricane but it's whining pretty good.

 

Wow, I feel sorry for the 4 cylinder crowd. My dauntless will cruise fast enough that I'm afraid to go any faster with that squishy of springs. I usually wuss out around 65-70 mph.

 

It's the telephone pole climbing 5.38s that do me in, but then it not a DD either.

 

With the 5.38s, I expect you're RPM limited with most tires. With any other gearing (ie different axle ratio, overdrive) you'll be power limited.

 

As has been discussed here before, sustained high rpm will not be good for an old f-head. "Top Speed" may not be "safe speed."

Pete

 

gotta disagree Pete
drove mine all over everywhere, Colorado and back many times
F4 5.38s Warn OD
could do it all day, week, year long, no problems

 

take a close look at this pic
this is a multi-club run from the 60s in the Calif desert
how many L4 and F4 (along with 6 cyls) are under these hoods ?
how do you suppose they traveled to the event ?
I don't see any car hauler type trailers....but I see travel trailers
many of these were 4 bangers (I'll concede some may be V8 as well)
and after the weekends fun, they drove them home
I know, because I've been there, done that...
this F4 being "ever so fragile" stuff....I don't know where it all got started

EDIT: photo credit: Desert Magazine, Nov 1971

 

Because V-8 guys saw 4cyl motors years ago that broke often. Too bad they then clumped all 4cyl motors into that category.

 

I knew I was asking for trouble. I've had a lot of f-heads and love 'em. I'm not saying they aren't a great motor.

But painful experience has shown me that it is easy to overspeed a jeep, and "I hear you knocking" becomes more than just a song lyric. At least with 'mature' engines. It is a long stroke motor, and jeeps were meant for endurance at low speeds.

But, again, I'm not a critic of the F-head. I just like to see them treated nice, as befits their age.

Pete

 

my overbored flathead on a 47 2a held up well in iowa and new mexico highways and interstates. but i held it to about 55mph coaxed it up to 65 for a bit but backed down (still had ross box steering and it's windy in march in nm there").
only problem came when the oil foamed on me on the way to santa fe from albq in 1971. then "i heard her knocking". engine was toasted. i hitched into santa fe and took a bus back to albq.

tough little engine

my 225 OF handles 70mph no problem in OD but i don't drive it that fast. too short a wheelbase. usually about 55 to 65mph.

 

Pete
I'm not attacking you, we're still friends
everybodys experience can be different than mine
If you know the engine (meaning it's in good shape mechanically) you shouldn't have any trouble at all for highway speeds.
that's all I'm trying to get across

 

Jim that is a very 8) pic

 

Thanks for all of the responses. The old F Head engine currently runs but is in need of a rebuild. I just wanted to know what my limitations were when I start driving it.

 

The old 4 cylinder engines in Jeeps were built for durability and low-speed torque, not modern highway cruising. They were originally available with plows and PTO pumps, but not reclining bucket seats and cruise control. The engine, when everything is within specs, can withstand highway speeds, but the driveline probably can't for long. The D18 T-case was not designed for sustained high speed, whether or not the vehicle has been retrofitted with unlocking front hubs. Compare the design differences of the D18 with the D300 for example, which disconnects the intermediate gears when in 2WD high range. The D18 spins the gears always, whether or not you are in 4WD, and high speeds challenges the gears, the bearings they ride on, and the oil, which will foam and cook at high speeds, as the T-case does not have much of an oil reserve and no cooling capacity at all. Old Jeeps are far better tractors than sports cars.

Whether or not the engine will survive at higher RPM, there is a practical limit to the speed you should drive something like a CJ-6 or CJ-5, regardless of the state of maintenance. The other many variables have been mentioned above, i.e., gears, tires, steering, and so on.

Once you have yours on the road, you will know. If it feels insecure above 55, don't go there.

 

Well I think this could be debated for a long time if not indefinitly, If you've driven stick before you know by the sound of the engine regardless of the make or design when enough is enough. And what's safe. Also personal preferance. (what you want to get out of it)

Play it safe 55-60mph Don't 55+