Hi All
Seems that I will be up for a cam for my Ser 11 Disco 4.0 auto in the near future.
It's done around 104,000 kilometers and getting a bit to much rattle in the top end, premature wear I suspect.
The plan is to pull it down and replace cam, lifters and check out rocker gear.
So, any suggestions as to what cam to use and also if there is anything else I should do while it is pulled down (top end that is).
BTW, I am happy with the performance of the standard factory cam , but if there is a better one with improved performance then that's what I would use.
TIA
Casey
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Disco Cam
Moderator: Micka
Is yours a Thor Motor? ie It has an inlet manifold that curves to each side of the rockers?
If so I would be very cautious of changing the cam as the manifold resonance supercharges the charge into the chambers. I think that if you put in a hotter cam you will lose mixture out the exhaust and not gain much at high revs because the manifold is restrictive at high revs.
If the old box type injection no worries but be aware any hotter cam will lose you low rev power and if you have an auto will make it seem sluggish,as an auto spends most of its time under 3000RPM and needs power for step off at 1500RPM. You also need a good vacuum signal to idle in drive.
The Thor has transformed my 3.9 because I now have 50% more power from idle to 2500RPM even though I have lost comparatively up high.
regards Philip A.
If so I would be very cautious of changing the cam as the manifold resonance supercharges the charge into the chambers. I think that if you put in a hotter cam you will lose mixture out the exhaust and not gain much at high revs because the manifold is restrictive at high revs.
If the old box type injection no worries but be aware any hotter cam will lose you low rev power and if you have an auto will make it seem sluggish,as an auto spends most of its time under 3000RPM and needs power for step off at 1500RPM. You also need a good vacuum signal to idle in drive.
The Thor has transformed my 3.9 because I now have 50% more power from idle to 2500RPM even though I have lost comparatively up high.
regards Philip A.
Yes it ihas the bannana type inlet manifold, I have seen them refered to as "high torque" manifolds.
I think it best to pull it down for a lifter replacement and inspect the cam then, as Desertrover suggests it may just be a lifter(s).
As mentioned before I am happy with the perfromance of the standard cam.
Cheers
Casey
I think it best to pull it down for a lifter replacement and inspect the cam then, as Desertrover suggests it may just be a lifter(s).
As mentioned before I am happy with the perfromance of the standard cam.
Cheers
Casey
Well, seeing you are 4/5 the way there , it might be worthwhile to change the head gaskets and have the heads overhauled. The 4.0 and 4.6 are noted for carboning the exhaust valve stems at 100 to 120 K, and then it all has to come down again!!!
I pulled my 3.9 down at 100K for a head gasket externally leaking between the head and block, and the exhaust valves were not far away from sticking.
Regards Philip A
I pulled my 3.9 down at 100K for a head gasket externally leaking between the head and block, and the exhaust valves were not far away from sticking.
Regards Philip A
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