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Old 04-09-2012, 05:08 PM
oldbogie oldbogie is offline
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Quote:
Originally Posted by Dannyringo
Hello:
Well, I learned something new yesterday that scared the living heck out of me...I bought the Lunati 60101LK cam for my rv that I plan on replacing the motor in...It appears that I lost some cam lobes with the missing I hear in the old motor, as well as blowing smoke out the tail pipes (175,000miles+)...I lost oil pressure last year and as a bandaid, I replaced the oil pump with a new HV melling...That did not correct the problem with low oil pressure once warmed up...
This past Feb. after traveling about 500 miles round trip, I heard a dreaded knocking sound that reminded me of a rod knock, but it sounded much higher and perhaps piston slap, or a piston pin knocking...Either way, it disappeared when I drove it 5 hrs later about 2 min. after starting it...It reappeared the next day when restarting it at a Auto Zone with a tech at hand, then disappeared after the 2nd heard knock...The tech agreed that it might be a piston, since the sound was near the top of a motor...

Either way, yesterday I learned that all of today's oil has limited zinc and other anti-friction additives in them and this is the sole reason why 1 in 10 motors upon break in fail~! This is according to Joe Gibbs racing...According to his site, if a person uses his breakin oil, they would have a better chance of a 1 in 40 chance of a hyd. flat tappet cam wiping out...
Although the odds are better, after reading his information and with the fact that I travel a lot in my Rv, I do not think it wise to go with a Hyd, flat tappet cam anymore, since I would have to have an oil after break in with high amounts of zinc, phosphorus and sulfur and low amounts of Calcium, which Calcium is a detergent used in today's oil... It is Calcium that washes away the anti-friction additives in oil and leaves the metal bare, causing extreme wear of the cam lobes....This is unacceptable in a pre-roller cam motor...
I would be curious how many people have already lost their motors because of this...Mine took 2 years for the lobes to wipe, now the motor is junk...

So, currently I am looking at two cams, one by Howards and the other by Lunati...I think Howards is going to be the winner for a Hyd. roller cam...

Any thoughts on this oil dilemma from the school of hard knocks and how it tore up your motor and learning about the additives being taken out of the oil you used?

I understand that at the end of 2011, they took most, or all of the zinc out of the oils currently on the shelves at your local big box stores, as well as big box auto parts stores...all because they wanted Cat converters to last 125,000 miles, or more and that zinc coated over time the platinum in the converters which then were either replaced, or illegally removed permanently.
Any thoughts?
This has been coming for a long time, it is the reason that the OEMs started switching to roller cams in the mid 1980's and finished up by 1996.

For many years an under the radar agreement left conventional levels of ZDDP in the 15-40, 20-40 and 20-50 weight oils especially those marked for Diesel engines. But now 25 years after the start of roller tappet conversions, that's changing.

Actually modern F/T cams and tappets are being treated to various surface hardening efforts and really aren't suffering failure rates any worse that pre roller history. GM and other engines that didn't use a thrust plate to retain the cam's fore and aft movements clearly suffer worse than engines that positively prevented movements. GM was repeatably sued for cam wear issues clear back to the 1960's and 70's so this isn't anything new. I started using a thrust button in regular flat tappet builds 35-40 years ago and the lobe/lifter failure rate went to zero.

From a spring stand point you're somewhat damned if you don't go to a stiffer spring and damned if you do. A soft spring lets the valve train bounce either from spring harmonics or slight over revving which bangs the lifter into the lobe. A stiff spring stops this but places a higher load on the lobe to lifter interface all the time. I think a 100 pound spring with the valve closed isn't enough. For a mild cam I like to see something more like 120-130 with a damper. Even for a mild engine I like to see a spring with a flat wound damper as this soaks up any random harmonics in the spring without having to use excessive spring pressure to shove these events above the usual rev range. You just have to crowd the advantages on your side when doing a build.

Obviously converting a non roller block to a roller is a time consuming and expensive undertaking. But with the availability of roller blocks with roller cams or of blocks that are machined for roller cams though may use a flat tappet (like GM trucks from 1985 to 1995) that include the machined provisions for a roller cam, there really isn't any excuse to fight the flat tappet wars unless you're building a class race engine that dictates a flat tappet by rule.

Bogie
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