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what cam to run
- Thread starter honda12
- Start date
MJ1990buildup
NAXJA Forum User
- Location
- Chesapeake Beach
are you keeping the disceplacement stock?
alot of people will take a cam used in a 252 and runn it in their 4.0's bored over
alot of people will take a cam used in a 252 and runn it in their 4.0's bored over
goodburbon
NAXJA Forum User
- Location
- Westcliffe Colorado.
a 35 dollar throttle body spacer netted me a 1mpg increase with that tire/gear combo. Stock cams are usually the most mileage friendly, as that is a big concern for the manufacturers.
BrettM
NAXJA Forum User
- Location
- michifornia
if you keep that gear ratio with 31s you may get better gas mileage with an RV cam
red91
NAXJA Forum User
- Location
- exact location unknown
Thats the set up I run on my rig RIGHT NOW with an AX-15 and I get 19-21 depending on whats going on. There's must be some other factors other than 200k for the decrease in milage.
old_man
NAXJA Forum User
- Location
- Loveland, Colorado
Surprisingly enough, I would call Crane and the other manufacturer's and ask the question. While an RV cam will give you more low end torque, My experience isn't that it helps mileage. If anything I've seen the opposite.
Anybody else have any experience. A cam isn't a cheap swap. Gears might be a viable alternative.
Anybody else have any experience. A cam isn't a cheap swap. Gears might be a viable alternative.
badjeepster
NAXJA Forum User
- Location
- Wyoming
I would also call as many cam manufacturers as I could. Most of them are very helpful.
MrShoeBoy
NAXJA Forum User
- Location
- Cincinnati, OH
old_man said:
He alreatty has the motor out and is in the process of a rebuild. A new cam is a no brainer!
I had an RV cam in my 4.0L and I liked it. With my right foot and 32s with 4.10s and a manual tranny, I got about 15-16mpg in the city and then 19mpg on the interstate if I kept it under 70mph. Crusing 75-80mph I got about 17mpg. I still have that cam and its for sale with only 15k miles on it! PM me for details
AARON
Clean Racing
NAXJA Forum User
- Location
- Bellingham, Wa
honda12 said:
Did You ask your machine shop what they reccomend?? I personally would ask the machine shop where he gets his cams, and see if they can regrind yours to a RV spec. Since the 4.0 benefits from torque more than horsepower. Just my $0.02 worth...
Scott.
Dr. Dyno
NAXJA Forum User
- Location
- Al Ain, UAE
honda12 said:
A 3" lift and 31" tires are not going to help gas mileage. If you're intent on keeping both, regearing to 4.10's would help performance and may also improve gas mileage.
Your Jeep is obviously built mainly for offroad use so you'll need a cam that produces abundant low rev torque. The stock cam will do fine but if you're intent on changing it, I recommend the Crane 750501 unit. You can get it under part no. CRN-750501 from Summit Racing but don't forget that you'll also need new Crane lifters.
thanks for your comments i do plan on 4:10 gears next summer with lockers this motor is all stock and before the lift and tires i got 18MPG and after it gets 14 if im easy on it and around 11MPG if i drive like a normal person.thats something i wasnt expecting i hope the rebuild will help. it sounds like a rv cam will help should i be concerned about the smog police?
- Location
- Terra Firma
I notice you did NOT mention what you run for gears. I have an '88 Comanche that until recently was lifted 4" and running on 31s. With 3.73 gearing I was getting 17 to 19 MPG in local driving and 19 to 21 MPG on the highway ... with the tailgate up.honda12 said:
Cam selection has to be made on the basis of the RPM range you will be operating in. Which means you cannot ignore gearing.
CW
NAXJA Forum User
- Location
- Coeur d'Alene, Idaho
I run a comp 250H in my 4.6L stroker and get 15mpg city and 22 highway. I am istalling this cam for one of my friends in a .030 over rebuild and I think he will be happy with the results.
