Premature cam failure, ZDDP issue??
- Thread starter Taylor
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This is a common problem with aftermarket cams on the Jeep forums. From what I gather the aftermarket cam lobes are much thinner than the O.E. cams. This puts more pressure on a smaller contact area of the cam.
See if you can find an old stock cam and see if it is infact wider than the aftermarket cam is.
The stock cams are not giving any trouble.
See if you can find an old stock cam and see if it is infact wider than the aftermarket cam is.
The stock cams are not giving any trouble.
Seen this before when the cam end play is greater than 5-8 thousandths. What is the builder setting his end play at?
Valvoline VR1 Racing Oil is made for street use. It has about 1300 t0 1400 ppm zinc and phosphors, made to protect high performance engines. comes in 10w30, 20w50, and straight weights 30, 40, 50, and 60. That's what I would use.
seems you have two sides of the fence on this, those who believe the newer oils are good enough for the flat tappets and those who feel it isnt.
I have two flat tappet motors and I run HDEO in both of them for the extra ZDDP
I have two flat tappet motors and I run HDEO in both of them for the extra ZDDP
I've heard a bunch of porsche owners and muscle car owners say they've lost engines because of the new oil. I think its [censored].
Seems worthwhile to play it safe with such a big investment.
Originally Posted By: TallPaul
Seems worthwhile to play it safe with such a big investment.
exactly thats what I do
Seems worthwhile to play it safe with such a big investment.
exactly thats what I do
OVERKILL
$100 Site Donor 2021
Originally Posted By: Taylor
I had just assumed that when the lobe wore to a certain point, the pushrod was able to jump out of place and be damaged.
Nope. You would just lose some lift. It would not have worn the base-circle of the camshaft.
Is it not possible to convert these engines to roller?
I had just assumed that when the lobe wore to a certain point, the pushrod was able to jump out of place and be damaged.
Nope. You would just lose some lift. It would not have worn the base-circle of the camshaft.
Is it not possible to convert these engines to roller?
Just to throw this out there, my LC2 has known cam-eating problems with aftermarket springs (never above 100lbs closed)and more aggressive ramp speeds. The lower ZDDP exposed an existing problem. The number 3 exhaust lifter bore was centered on the lobe in some blocks causing the lifter to not rotate and eat the cam.
Any of these 4.0 engines showing a pattern of the same lobes going bad?
Some people break the cam in with old stock springs and then install the stiffer springs.
I agree with Overkill, forget these problems and go roller if possible.
Any of these 4.0 engines showing a pattern of the same lobes going bad?
Some people break the cam in with old stock springs and then install the stiffer springs.
I agree with Overkill, forget these problems and go roller if possible.
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Going roller on a 4.0 jeep engine is difficult. I guess if you could manage something like the rev kits that were used on the Ford Cortina engines it might work. Cams run about $800 each (custom ground) and you need to (perhaps) get the Crane (iirc) lifter bore inserts to keep the rollers parallel.
HP out of these engines is very expensive ($75-$150 each) and mostly a waste of time. Torque is cheap with the 4.2 crank. It's up there with the BBC for stroke.
but back on topic ..
We're debating failures in non-stock cams with high spring rates. How can we navigate oil spec's (SH, SJ, SL) when the standards that they met were with 180lbf springs and "may have" managed much more in their excesses of additive potency?
HP out of these engines is very expensive ($75-$150 each) and mostly a waste of time. Torque is cheap with the 4.2 crank. It's up there with the BBC for stroke.
but back on topic ..
We're debating failures in non-stock cams with high spring rates. How can we navigate oil spec's (SH, SJ, SL) when the standards that they met were with 180lbf springs and "may have" managed much more in their excesses of additive potency?
I believe Comp and Crane Cams insist on the use of their zddp additive for flat-tappet apps to prevent failure of their cams. Sounds inter-related to this discussion.
http://cranecams.com/pdf/548e.pdf
http://cranecams.com/pdf/548e.pdf
MolaKule
Staff member
If you run a regular SM oil in a modified street or racing engine, what do you expect when using high pressure springs and gosh awful lobe profiles.
Invest in something like Redline or Amsoil racing oils with a good assembly lube and or run-in oil.
Invest in something like Redline or Amsoil racing oils with a good assembly lube and or run-in oil.
We had a closer look today at the lifters. What I didn't notice was that one lifter was worn completely concave, and had a hole in the center of the wear surface! I felt pretty silly that I missed this. The bad lobe also had a very concave lifter.
My mistake, I had missed this when I pulled the lifters and put them in a box. This explains how the rod was able to jump out.
The pistons, valves etc all looked good.
Max RPM = ~5300
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My mistake, I had missed this when I pulled the lifters and put them in a box. This explains how the rod was able to jump out.
The pistons, valves etc all looked good.
Max RPM = ~5300
__________________
ACEA can be found here and kinda leaves off where the US and API or even ILSAC leave off. We in the US don't really test oils for flat tappet wear anymore, but the Europeans still do. So, you'd want an oil that's tested for flat tappet protection. The API CI4 is the old spec of diesel oils before they changed to CJ4 for emissions reasons. The same reasons why ZDDP and SAPS were removed from gas engine oils, so goes with diesel oils.
Some still try to cling to zinc laden oils, but it's not the real goal. The goal is to use an oil that's designed for flat tappet engines, and break-in properly, and monitor the results. Zinc makes it easier to use a cheap oil without catastrophe, but the proper oil can protect far better without zinc, proving that zinc isn't the only recipe for success.
Some still try to cling to zinc laden oils, but it's not the real goal. The goal is to use an oil that's designed for flat tappet engines, and break-in properly, and monitor the results. Zinc makes it easier to use a cheap oil without catastrophe, but the proper oil can protect far better without zinc, proving that zinc isn't the only recipe for success.
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