Cam question

[Mike Mike]

First time in this section. Anyway need to rebuild my 94 4.0. Thinking 30 over bore, chyr HP head gasket, port and polish on head, header and cat back. Looking at cams, want to pull peak torque down to the 3200 -3500 rpm range. Any suggestions.

 

[casual]

Dude I'm going through the same thing. I wanted a stroker at first but now I think I'll be fine with a rebuilt stocker lol. I picked up a JY motor dirt cheap $120 and I'm doing .30 over or possibly a .60 over and a Comp 68-231-4 cam w/ 111LSA. Its operating range is 800-5000rpm per Summit Racing.
Theres also a Comp 68-232-4 w/ 113LSA, its operating range is 800-4800rpm. So its not as stronger up top but will have a little more down low. The 232-4 will have a smoother idle & is probably better for daily driving. The 231-4 is the same except a choppier idle & more top end. I read a few guys stalled their AUTO trans when coming to a stop. But a little more idle rpm will fix that!
I'm into go fast (JeepSpeed) type stuff and live in the desert, so I think the 231-4 fits my needs. I say grab the 231-4 and have fun, the idle isn't that bad at all. Just ask around.

YOU WILL ALSO NEED LIFTERS & NEW VALVE SPRINGS WITH EITHER CAM.
I'll be ordering this kit from Summit Racing, has everything I need.
http://www.summitracing.com/parts/CCA-K68-231-4/

 

[gradon]

Don't know if you are aware or not, but apparently you can't use the springs in the Comp kit on the 4.0 head, so you'd be better off just getting the cam and going the mopar P5249464 spring and P4452032 retainer route.

 

[Dr. Dyno]

Correct. The valve springs/retainers in the Compcams kit only fit on the 258 head so you'd definitely need the Mopar stuff.

 

[badron]

Try calling the MAYOR cam manufacture and asking them. What cam to use for your set up.
Few people know more about there cams then them.

 

[casual]

Thanks gardon. I was told the opposite on another site lol. That you can use em in the 4.0 & not the 258.
But thank you very much on that info, that saves a big headache!

 

[Talyn]

Try calling the MAYOR cam manufacture and asking them.

Do you have a URL for mayor? Google didn't find anything for me.


As for cams I recommend calling smaller companies and asking for a custom grind on your engine, transmission, gearing and tires, and usage specs. Comp Cam and other large companies won't do that and would recommend and off the shelf grind.

 

[DieselSJ]

Call Clay Smith about your cam. They ground the cam and did the head work on our Jeepspeed. They grind all of the cams for Hesco. They know 4.0 stuff.

 

[NorCalChris]

Don't know if you are aware or not, but apparently you can't use the springs in the Comp kit on the 4.0 head, so you'd be better off just getting the cam and going the mopar P5249464 spring and P4452032 retainer route.

x2

 

[piratius]

I will also verify that the springs with the kit do not work, even though COMP initially told me that one set would (926-11 or something?)

The springs are much larger diameter than the stock ones, and don't sit properly without further machine work on the head (which is do-able, but why?). Then, the stock valve retainers won't work, and COMP doesn't make a retainer for that spring with an 8mm valve stem, so you'd have to put different valves in at the same time.

The MOPAR P5249464 spring and P4452032 retainer work well - you can use the stock valve locks, or purchase new ones, they're actually pretty cheap compared with $12 per spring and $10 per retainer (I think one "bag" of them from summit was $19.99 - it was listed as only doing 4 cylinders (8 valves) but had enough to do all of mine!)

I just had my COMP cams SK68-232-4 cam package fail during the break in procedure. Turns out it chewed up all the lifters (which all had the appropriate bore tolerance and dropped in smoothly and rotated freely when new) so badly that it wore holes in the bottoms of two of them, causing them to catastrophically lose oil pressure and not open the intake valves in cylinders 2 & 3 at all. Then the lifter not keeping pumped up caused it to slap the cam as it rotated instead of keeping continuous contact, which wiped the cam... :flamemad:

Oh yeah, they also sent me the cam with the sprocket pin in the end in the wrong hole (180* out), so when I put it all together and timed the motor, #1 was firing when #6 was TDC compression stroke. Luckily, the 4.0L motor is symmetrical, meaning you can just spin the distributor 180* to correct the problem, and it fired right up instantly. Still was an annoying problem to troubleshoot...and it ran great for 15 minutes until the lifters blew out.

Just makes me wonder about the tech and/or QC system in place at COMP - potentially careless assembly, people telling you one product works then being contradicted by another (who is correct), and following ALL of the installation and break-in procedures to the LETTER (including the use of break-in additives!) and having parts fail almost instantly. (For reference, the 100,000 mile cam/lifters i took out showed almost no wear at all, just a super-slight cupping on the bottom of the lifters)

~Brad