[Guest]

I am finally going to put the MPI kit in. I already have a 4.0L HO head and I figuire while I am in there I may as well change the cam to take full advantage of all the Mods the engine has. I am not looking for anything super drastic, I am hoping to get something that will be good on the Highway as well as the trail. I called JeepConnection and he suggested the "smallest one" but he only has stuff for a 4.0L engine, and Mopar said that wouldnt work in the 4.2 block. Could anyone tell me what kind of specs I should look for in the Cam, and best yet a good place to get one? would be greatly appreciated.

 

[Guest]

just in case for specs, I have an 87 YJ with a 258 and 4.0 HO head, swapped in an AX15 too

 

[865]

I suggest you call HESCO. I believe they sell a cam that is compatible with your application.

 

[Tippy]

I did the same mods you are doing about 2 years ago. I used a COMP cam grind # 260H (PN 68-201-4). It has 260 duration and .447 lift. It makes good power from 1200-4400 rpm. It lopes a little, but not like a dragster. Makes better power than stock. Stay away from something with a big lope. I'd get a whole kit - cam, timing chain and lifters since you are in there. The only thing that I didn't like about the comp timing chain is that you couldn't degree it. I don't know how much difference that would make, but my setup runs a little hot (210* w/ 3 core radiator on the trail) and Hesco says that is my problem. Hesco sells a double roller timing chain set up that can be degreed. I don't know how much it is, but it might be worth looking at. I think an electric fan will solve my cooling problems as I have replaced everything else!!

 

[elusive]

In reply to:

Mopar said that wouldnt work in the 4.2 block

[/ QUOTE ]

sounds kinda odd since I know for a fact I have a 4.2 cam in my 4.0

I agree with tippy's cam choice, though the split duration 4.0 cams are nice too

 

[Guest]

seemed odd to me too, but I dont want to put something iffy in the truck and then have to tear it down again.

 

[jfralph]

Sounds real strange. I installed a chrysler (4.0) cam in my 4.2 when I installed the MPI. Mopar has some good cam choices. Remember, to much duration and you start loosing low end performance. On mine, I looked at the stock specs and went with the cam with more lift and similiar duration.

Good luck.

 

[LEVE]

1. To quote Twosocks:

In reply to:

I suggest you call HESCO. I believe they sell a cam that is compatible with your application.

[/ QUOTE ]2. He's given the best information you can get.
3. The HESCO/SMPI kit is somewhat hard programmed.
4. For a specified duration and lift of a specific cam.
5. You change the cam,
6. And you have to change the programming of the Eprom,
7. To take into effect the changes made by the cam.
8. Otherwise there's not a happy compromise,
9. And your plans for a hotter cam will be defeated.
10. This is a closed system.
11. You change Part A,
12. And if affects Part B.
13. To do it right you've got to know,
14. The relationships between each part,
15. And how a change affects the system.

 

[1274]

Xburn3
I have a 258 with the 4.0L clifford head conversion kit. I ran their headers and cam. I also run the Megasquirt MPI. The 264 cam has great throttle response and develops tremendous low end torque.

I have listed the web site below.

http://cliffordperformanceshop.com/catalog/97-2021-efi_camshaft_hyd__type_1710694.htm

http://www.bgsoflex.com/megasquirt.html

Have fun,

Fran

 

[1274]

Xburn3
Here is another sitr you might find interesting http://www.amcwc.com/techtips.html

Fran

 

[Guest]

Wow, thanks for all the replys. Couple things:

I cannot really understand why the 4.0 cam wont work with the 4.2 either. One of the tech guys at Mopar checked it out and told me no. Perhaps the tow have some sort of a difference, but I can't see how being that the head is a 4.0L to begin with.

And LEVE, I am a little confused about your reply. At this point I agree calling HESCO is the way to go, but it sounds like your telling me I will need to reprogram the cpu too? Maybe I am not understanding right. Benny wasn't there today and everyone seems to tell me he is the man to talk to.

I guess overall I was hoping a cam was made to utilize the full output of the MPI and the 4.0L head. I am (of course) looking to pass emissions as well as not have any adverse effects on the engine (heating probs, etc). Just tryin to sqeeze what I can out of this engine.

 

[RRich]

I'm not familiar with your injection system. But -

You should know - any system that uses a device to measure airflow, like a map sensor or mass airflow sensor will not tolerate a cam with more overlap than stock - which is usually minimal. You can push that by about 10%, but more will give that "dragster lope" - or "plug wire off" lope without any increase in power, often even less.

What happens is the extra overlap makes the intake pulsate, driving the map/maf sensor nuts! It won't give the right readings to the ECM - makes for the wrong mixture.
(I've done experimenting on using a long hose to the map, trying to dampen the pulsations - it works - but then you lose throttle respose bad.)

You can go much higher lift, even a tad more duration, but not overlap. Honest, and knowledgable, cam grinders will tell you that.

A simple way - ratio rockers for more lift - with more spring - within reason of course. Not sure if anyone makes them for your engine, you might have to modify some.

 

[Guest]

Just for an update: I talked with Hesco and Benny suggested their H264-14 (looks like * Lift-.470 * Duration- [email protected] * Lobe centers- 114), and a double roller timing chain. Not quite sure if that will yeild stellar results but I have heard a lot of good things about Benny so I guess I have nothing to do but trust him. Hopefully someone could back this suggestion up, if not I hope someone else in my situation benefitted from the info.

 

[LEVE]

In reply to:

And LEVE, I am a little confused about your reply. At this point I agree calling HESCO is the way to go, but it sounds like your telling me I will need to reprogram the cpu too?

[/ QUOTE ]1. Yep, you've got it...
2. The computer is programmed for a specific RPM/Fuel step.
3. When you put in a cam that's not for the system,
4. The computer is still programmed for the OEM cam.
5. So, unless you re-program the computer,
6. To take in effect the newer, hotter cam,
7. You've done a disservice to the sytstem,.
8. By thowing everything outta specifications.