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Help with cam

Posted: December 21st, 2009, 7:53 pm
by LetchcoreCJ7
My specs:
1991 4.0l engine
KB944 pistons .040 over
4.0l rods
4.2l crankshaft
redone head. no porting.

I am looking for a cam and new springs for my build. I am not shooting for max power. I want torque and durability/reliability. Most all the comp cams give me about 8 to 1 DCR. I thought I read the Comp Cam springs require head modification? Is that why people use the Mopar springs?

Looking at this one. Is this bolt in? In other words does the head have to be modified to run the springs? What about with the 68-232-4 and these springs?
http://www.summitracing.com/parts/CCA-K68-201-4/

Re: Help with cam

Posted: December 21st, 2009, 8:19 pm
by dwg86
You cannot use the comp springs because they don't make a retainer and keeper for the Jeep 4.0 8mm valve stem. The springs and retainers that comp sells with there cams are for the 258 3/8 valve stem. The only drop in spring available for the Jeep 4.0 is the mopar performance part# P5249464 and mopar performance retainer part# 4452032.

The stock springs are good for up to .450 valve lift. You still might want to replace the stock springs if they have a lot of miles on them and are weak. Your machine shop can check your old springs to see if they are still in spec.

Re: Help with cam

Posted: December 22nd, 2009, 8:14 am
by LetchcoreCJ7
If I use the Mopar P4529228AB i get a DCR of 8.2. If I use the Comp cam 68-232-4 I get a DCR of 7.8. I am guessing if I want to use mid grade fuel the Comp will be better?

I can still use my stock lock with the mopar performance valves and retainers right?

Re: Help with cam

Posted: December 22nd, 2009, 5:31 pm
by dwg86
I run 87 octane with 7.75 DCR.
Stock locks will work.

Re: Help with cam

Posted: December 30th, 2009, 7:39 am
by LetchcoreCJ7
I ordered mopar performance part# P5249464 and mopar performance retainer part# 4452032 and gave them to my engine guy and he said it lowered the spring height and raised the spring pressure to 145lbs. He said that was way to high and wont install them. Is he wrong???? :huh:

Re: Help with cam

Posted: December 30th, 2009, 8:40 am
by dwg86
The only thing I would know to do, in this case, is to have the spring pads machined to raise the installed height and lower the spring pressure.

Re: Help with cam

Posted: December 30th, 2009, 8:52 am
by LetchcoreCJ7
dwg86 wrote:The only thing I would know to do, in this case, is to have the spring pads machined to raise the installed height and lower the spring pressure.
What spring pressure should I shoot for?

Re: Help with cam

Posted: December 30th, 2009, 10:20 am
by SilverXJ
LetchcoreCJ7 wrote:I ordered mopar performance part# P5249464 and mopar performance retainer part# 4452032 and gave them to my engine guy and he said it lowered the spring height and raised the spring pressure to 145lbs. He said that was way to high and wont install them. Is he wrong???? :huh:
That doesn't sound right. They shouldn't have changed the install height noticeably. At 1.64" they should be around 113 lbs. What install height did it come to? One other thought is that the springs are new and will reduce pressure when broken in. I would shoot for 100-110 seat pressure if you are having the seat machined. And make sure all the parts are correct.

Re: Help with cam

Posted: December 30th, 2009, 2:42 pm
by woodjeep
I hope that LetchcoreCJ7's numbers are somehow wrong. I too installed the Mopar perf springs and retainers on my 96 head. I had read that they were an almost exact replacement as far as spring height was concerned. It's sitting on my garage shelf now awaiting springtime. They will be driven by a Comp Cam 68-232-4

Re: Help with cam

Posted: December 30th, 2009, 3:18 pm
by LetchcoreCJ7
I honestly dont know what to due but take the head somewhere else and see if they get the same thing. He took the mopar springs off and shimmed my stock springs .060 to get to 100lbs seat pressure. I dont know if this will work for the 68-232 comp cam now or not? I am temped to buy a spring compressor and measure the height of the mopar springs myself. If the height is right I assume the pressure would be what the manufacture specs out. I double checked the part numbers of the springs and retainers and they are right. These are the parts everyone else is using. My head is the 91' HO 7120 head. I dont get it? :huh:

On a side note what spring seat pressure do the comp cam 68-232 and the mopar cams recommend?

Re: Help with cam

Posted: December 30th, 2009, 7:45 pm
by dwg86
LetchcoreCJ7 wrote:I honestly dont know what to due but take the head somewhere else and see if they get the same thing. He took the mopar springs off and shimmed my stock springs .060 to get to 100lbs seat pressure. I dont know if this will work for the 68-232 comp cam now or not? I am temped to buy a spring compressor and measure the height of the mopar springs myself. If the height is right I assume the pressure would be what the manufacture specs out. I double checked the part numbers of the springs and retainers and they are right. These are the parts everyone else is using. My head is the 91' HO 7120 head. I dont get it? :huh:

On a side note what spring seat pressure do the comp cam 68-232 and the mopar cams recommend?
The stock springs are only good up to .450 lift. If the stock springs are shimmed .060, that would decrease the useable valve spring lift to .390. I would shoot for 110#. The springs might loose a little tension after break in.

I am using the MP springs on my stroker, 7120 head with no problems. I am running SBC 1.94/1.50 valves, but I don't remember what the installed height ended up at.

Re: Help with cam

Posted: December 31st, 2009, 6:54 pm
by SilverXJ
LetchcoreCJ7 wrote:I honestly dont know what to due but take the head somewhere else and see if they get the same thing.
That might be a good idea.
He took the mopar springs off and shimmed my stock springs .060 to get to 100lbs seat pressure.
Thats a bad idea and won't work with the 68-232-4. Sounds like some crap Titan tried to pull on me.. except the screwed up the valve job so bad there were 3 or 4 different thickness shims on the head.

Re: Help with cam

Posted: January 10th, 2010, 9:44 am
by LetchcoreCJ7
So I went with the Mopar P4529228AB because I am trying to use MOPAR parts where possible and the lobes are bigger like stock lobes. Also it starts to make power at 900rpm which should be good for me beacuse I am only doing some light towing and offroading. The lift is .430 on this cam. I have stock springs or the Mopar performance part# P5249464 valve springs. Which ones should I use? The Mopar springs wont be to stiff for this cam will they? :huh:

Re: Help with cam

Posted: January 10th, 2010, 10:03 am
by dwg86
LetchcoreCJ7 wrote:So I went with the Mopar P4529228AB because I am trying to use MOPAR parts where possible and the lobes are bigger like stock lobes. Also it starts to make power at 900rpm which should be good for me beacuse I am only doing some light towing and offroading. The lift is .430 on this cam. I have stock springs or the Mopar performance part# P5249464 valve springs. Which ones should I use? The Mopar springs wont be to stiff for this cam will they? :huh:
I wouldn't use the old valve springs with high miles. If you are using the 28ab cam with .430 lift, you can use the Mopar Performance spring P4529215 made for the Jeep 4.0 (1988-02 Jeep 4.0, conical spring, up to .430 lift) $5.95 each.
http://www.jeepconnection.com/parts/index.html
About half way down the page.

Re: Help with cam

Posted: January 12th, 2010, 7:08 pm
by LetchcoreCJ7
dwg86 wrote:
LetchcoreCJ7 wrote:So I went with the Mopar P4529228AB because I am trying to use MOPAR parts where possible and the lobes are bigger like stock lobes. Also it starts to make power at 900rpm which should be good for me beacuse I am only doing some light towing and offroading. The lift is .430 on this cam. I have stock springs or the Mopar performance part# P5249464 valve springs. Which ones should I use? The Mopar springs wont be to stiff for this cam will they? :huh:
I wouldn't use the old valve springs with high miles. If you are using the 28ab cam with .430 lift, you can use the Mopar Performance spring P4529215 made for the Jeep 4.0 (1988-02 Jeep 4.0, conical spring, up to .430 lift) $5.95 each.
http://www.jeepconnection.com/parts/index.html
About half way down the page.
I already have the Mopar performance part# P5249464 valve springs. Do you think there is a reason then would not work with this cam?