power

[B_Fisk]

I am looking for advice. I have an 81 wagoneer with a 360 in it. I pull a 5000 pound trailer with it and I use it to get into difficult locations for hunting. Occasionaly I pull trees that fall on our property.My jeep seems to pull an extreme amount of weight, if your not in a hurry. I requested info on swapping motors yesterday, and joe gave me quick and accurate info. I am wondering what my best option is as far as increasing my jeep's ability to pull my trailer over the mountains while maintaing better speeds. I can either install a 4 barrel manifold,a huge carb, and a hot cam, or install a 401 enginge. Wich of these options will best fulfill my desire for more power?

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by B_Fisk:
[QB I am wondering what my best option is as far as increasing my jeep's ability to pull my trailer over the mountains while maintaing better speeds? [/QB]<HR></BLOCKQUOTE>

80 and later Wags have really poor gearing for towing. Stock is 2.73's but even the tow pack option is only 3.31's which in real world specs aren't tow gears either. Ok for a pup trailer to go to the dump but serious towing...no.
I wouldn't put any money into eng mods/4v carb/RV cam/ etc for mountain towing w/o changing gears. It would help but the biggest bang-for-the-buck I think you can do is go with 3.73 gears. It's gonna run ya $1000-$1200 to have a shop do it but it will make a "major" difference in towing ability/speeds where dumping $500 into the motor won't do much for towing with the stock axles. If you can afford both RV cam etc "and" gear changes you've got it made. Considering the weight of a Wag even w/o trailer 3.73's won't seriously affect mpg's. Both my trucks run 4.09's w/360's rated at 195hp and pull 10 mpg in town and 12 freeway flying.
3.73's are IMHO the best all-around-compromise gearing for streetability/towing/offroad.
Your motor has enough of power...your stock axle gearing just won't allow you to maximize it.

[B_Fisk]

Thanks again joe. you really know your stuff.I just discovered this website and I've really learned alot. I want to increase my lift and tire size. Using the info you gave me, I want to try to accomplish a final gear ratio of 3.31:1? my jeep really likes snow and ice. I was amazed. I took my kids sledding in Hoodriver Or. I didn't get stuck untill I got into snow above four feet on the trail. The snow packed under the body and lifted the tires off the ground.6200 pounds of weight, I didn't think snow could lift that much weight. Didn't need chains on the icy roads at all. Really sure footed. I put my stock jeep in places the built Ford and Chevy trucks couldn't go. HaHa.

[NYC]

Joe.
This is a topic I've been thinking about a lot recently - I'll be towing a CJ on a trailer across the country this summer.

I've got a rebuilt 360 (an RV cam was used) and 3.31s (factory tow pack). I've considered 3.73s but I already look for a 4th gear when I'm on the highway. I can't imagine another 500 RPM (that's a guess)

Will the reduced strain on the motor (using 3.73s) off-set the increased RPM and reduced MPG.

I don't know if I can take 35 hours at 2,800 RPM even if the motor can.

What do you think?

[ClarkstonGT]

Maybe someone can help me with something I have been confused about. I think I once read on here that at some point in the late 80's, Jeep did away with the 3.31 gears for the tow package and that all GWs got the 2.73 gears regardless. It probably had to do with CAFE standards and gas mileage. Does anyone know for sure. I have the tow package on my '88 (identified by the tranny cooler), but I am pretty sure my gears are 2.73 (stamped on the housing). Any info.?

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by NYC:
Joe.
I don't know if I can take 35 hours at 2,800 RPM even if the motor can.

What do you think?<HR></BLOCKQUOTE>

I don't think that's too bad considering you're towing...but may just be me. Since you're running tires about 10% larger than stock you've already essentially dropped the effective gear ratio by 10% too.
3.73's w/31's at 65 mph should turn 2625 rpm's. Again I don't think that's bad at all considering the FSJ, the trailer, the CJ...you'll be rolling almost 10,000 lbs down the road.
I guess times have changed...3.73's used to consider pretty high gearing when 4.10's were pretty much stock and options 4.27,4.56 4.88's etc.
Today 3.73's seem to be thought of as really low gearing. Maybe I'm just getting old smile.gif
FWIW I run my rigs at hwy speeds across WA state fairly often and can live with it just fine and all 3 of my FSJ's are geared with 4.09's

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by B_Fisk:
I want to try to accomplish a final gear ratio of 3.31:1? <HR></BLOCKQUOTE>

Figure roughly the % in tire size increase reduces you axle ratio by the same % so running 31's rather rhan the stock 28's with 3.73's will roughly get you down to 3.36 which is pretty close. Using a formula to get new effective gear ratio you still about the same answer.

new ratio = (old dia x old ratio) / new dia.

new ratio = (28" x 3.73) / 31"

= 3.369

[jeepbob]

With a 5000 lb trailer you should be running no less than 3.54's and 3.73's would be prefered. When you are pulling heavy loads you need the gears to do the job. As far as engine mods, a 4v manifold and 600 cfm carb are a good choice. I would inspect the cam lobes for wear and run no more than an Edelbrock performer cam (270/280 adv dur)or equivliant. This cam is just a small step above a stock cam and will give good torque and power on the low and mid ranges which is where it is needed. AMC cams are known to wear out before the rest of the motor. Also I would change the timing chain as if you have more than 70000 miles it is due.

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by ClarkstonGT:
Maybe someone can help me with something I have been confused about. I think I once read on here that at some point in the late 80's, Jeep did away with the 3.31 gears for the tow package and that all GWs got the 2.73 gears regardless. It probably had to do with CAFE standards and gas mileage. Does anyone know for sure. I have the tow package on my '88 (identified by the tranny cooler), but I am pretty sure my gears are 2.73 (stamped on the housing). Any info.?<HR></BLOCKQUOTE>

I'm pretty sure that's just a rumor. If anything I'd say there are more 3.31 equiped late FSJ's than there are w/2.73's
I may be wrong here but I think "all" FSJ's w/ auto trannies have coolers on them, it's not just the ones with the tow pack option.

[Bob Barry]

The tranny cooler, and the 3.31 gears, were options available separately. When you bought the factory Class III tow package (tow package "B", I believe), it was supposed to include both the tranny cooler, the 3.31 gears, the hitch and the wiring with the relay box. I don't know if the Class II tow package (tow package "A", I believe) included all those features, or not.

It's always possible that the cooler and hitch were dealer-installed, in which case I doubt they would have changed the gears from 2.73's to 3.31's.