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Camshaft advance

A

Antiferret

NAXJA Forum User
Location
Redbank Plains
has anyone tried this to introduce lower torque?
i will be going to 32 inch (actually 31.7 inches) by 7.50 inch (skinnys!) and seems like a half decent way to get back some driveability and towing prowess.

what are your thoughts/experiences?
 
It'll lower the power band, might work. What year? I heard some years already have the cam advanced.


BTW, most folks change the gears. :)
 
'96.

apparently chrysler retarded the camshaft to help meet emissions without using a knock sensor. seems reasonable. i however think burning less petrol (gas to youse) while travelling to and from places to wheel seems like a better thing to do with an older vehicle that spits out crap anyway.

BTW, i'm not a greenie:explosion

if someone has done it, i'd like to know how far i would be able to advance the cam before i start breaking things. i cannot really afford to break things, thats why i go gently offroad.
 
Advanceing the cam reduces the low end torque but allow to engine to turn higher RPM's.
If you are looking for more low end torque and power, you need to retard the cam.
For me, I prefer to re-gear than mess with the engine. I think it is well optimized for what it is. Well, I think I will utilize some long (runner) headers for more low end torque since I very rearly push my XJ beyond 3,000 RPM.I do that only to allow me to evertake another vehicle before dropping back to my normal 2,000 to 2,300 RPM.

I used to fool around with cam degrees when I raced (amature) power boats equipped with single or twin Chevy 350 cc or 454 cc bored and stroked.
 
Hello sorry you have it backwords I use to build and race SbF 289 in mustangs and By advancing the cam, the valves open and close earlier. Duration and overlap remain unchanged. Advancing raises the cylinder pressure (due to earlier valve closing) This improves low end and mid-range torque at the expense of some top-end power. The result is similar to using a shorter-duration cam since the intake valve closing point is more critical than its opening point.

Retarding the cam so valves open and close later has the opposite effect. This should increase top-end power, at the expense of low end, and mid-range torque. Thus: 1) Advance Cam: More low and mid-range torque, 2) Retard Cam: More top-end power. I used a 3 keyd crank gear one key advances one is straight up or stock timming and the other retards the timming. the keys on most are 4 dregess make a big diffance.I have seen some old timmer set a stock chain up one notch fast and get away with it .Dont know if a 4.0 will work or not because with one notch is like 8 or so advance.They make a 3 keyed timming chain set for 4.0 but it like 140.00 for it .
 
My stroker has a timing set with the 4* advanced or retarded positions. We set it even, but one of these days I want to set it retarded to try for more top speed......or just change cams.
 
Will the ECM over ride your distributor setting if you advance the timing?
 
you cant advance the dist timming it comes off the CPS and the ECM controls it but the cam timming it a diff thing all together and the ECM has no control over it.
 
If you are looking to gain drive ability and get better power for towing, you need new gears.

Not only will it put you in the right power band, but it will lessen the strain on your tranny, which builds lots of heat when under geared.

The cam might be something to look into once re geared, but IMO, unless you are building a stroker, you don't need to do much.
 
I think it would be a upgrade thing to do you gain some low end from it .If a person was doing a RMS then I would chainge the timming chain if it has a lot miles on it even a stock replacement will get some power back just from the chain strech by setting the cam timming back to were it should be. if you wanted to upgrade to a 3 keyed timming set and set it advance and try it . heck we spend $200.00 on stuff that dosent give back as much power and low end.
 
Once upon a time, in a galaxy far, far away...

Renix had a "high-altitude" option for the CPS/CKP. The sensor was offset instead of centered on the mount.

You could try modifying a CPS/CKP.
 
I read that some where i wondered if it works on a 91 and up 4.0L mines a 92 was thinking about doing that gain of about 2 to 3 dregess from what I read.
 
Dobbs said:
I read that some where i wondered if it works on a 91 and up 4.0L mines a 92 was thinking about doing that gain of about 2 to 3 dregess from what I read.
Click to expand...

It should work, it is simply changing the point at which the CPS/CKP is telling the ECU/PCM that things are lined up--the ECU/PCM doesn't know it is being "misled".

Kinda like the entire world versus the climatologists/Global Warmers. :D
 
srmitchell said:
If you are looking to gain drive ability and get better power for towing, you need new gears.

Not only will it put you in the right power band, but it will lessen the strain on your tranny, which builds lots of heat when under geared.

The cam might be something to look into once re geared, but IMO, unless you are building a stroker, you don't need to do much.
Click to expand...

i initially thought so too. but lowering the powerband (torqueband) should bring immediate benefits without gearing.

my holden commodore (aussie car) weighs more than the xj and is powered by the 3.8 buick engine (heavily updated). it developes most of its torque just above 1800rpm and is really punchy and AWESOME for towing despite being a small engine (3.05 diff ratio on 235/65 r15).



get superb economy on the commodore and looking to make the jeep a low rpm gruntbox.

"Kinda like the entire world versus the climatologists/Global Warmers"

(i like this quote btw!!)
 
srmitchell said:
If you are looking to gain drive ability and get better power for towing, you need new gears.

Not only will it put you in the right power band, but it will lessen the strain on your tranny, which builds lots of heat when under geared.

The cam might be something to look into once re geared, but IMO, unless you are building a stroker, you don't need to do much.
Click to expand...

I agree, i once blew a planetary gear out the side of my transfer case on a long drive on the freeway due to heat. Now that i'm re geared I've done loads of freeway miles without a problem. Gears are by far the best way to add power to your rig... Next to a stroker, but i would still re gear even if i had a stroker.
 
Last edited:
nochance9 said:
I agree, i once blew a planetary gear out the side of my transfer case on a long drive on the freeway due to heat. Now that i'm re geared I've done loads of freeway miles without a problem. Gears are by far the best way to add power to your rig... Next to a stroker, but i would still re gear even if i had a stroker.
Click to expand...

righto.

i have heard that the aw4 can take about 600hp or so (correct me if i am wrong) i have also heard it take a supra into the 12 second 1/4 mile bracket standard. i thinks if i have a large aftermarket cooler + fan i should be sweet (i don't have to worry about minus temps and sluggish shifts here, its pushing 40 celcius outside! ). regearing is a pain here (legalities and spares, otherwise it would have a d44 at the back) versus drilling 1 new cam pin hole (cost of a new timing cover gasket).
 
Have you actually seen the torque curve on a 4.0,Its basically flat!
Just do gears!
 
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