What is the common thought about using a zinc
additive, or an oil that contains zinc? any
harm? any benefit?
If you Google mtfca: what kind of oil you'll find enough reading material to make it your life's work. When it comes to zinc in particular, if I remember correctly, its use in a Model T is generally considered a waste of money. Here's my opinion on oil: http://dauntlessgeezer.com/DG103.html.
Including the zinc additives won't hurt anything but doesn't provide a significant benefit either. It came along to help limit wear on flat tappet engines that had high tension valve springs. Think mainly 60's and 70's high performance motors. Model T's with light spring pressures really don't need it.
From a slightly different perspective - how many miles do people really put on their T's? There are some serious drivers but most of us put at best a few thousand miles a year on our cars. Even cars with many decades of driving typically show limited cam/lifter wear.
The need for ZDDP came during the horsepower race during the 50's and 60's when higher rpms made harder valve springs needed, and thus higher forces between cam and lifter. A T engine has but a fraction of those forces at the camshaft and thus no need for special additives in the oil. The low rpm makes lead replacement additives in the gas to save the valves equally unnecessary - tetraethyl lead wasn't even available until after the T heydays.
I don't use any additives and don't worry about it either. The T also seems to not care.
I had an adjustable tappet adjusting bolt
head shear off after 3 hrs of operation since
new installation. Exhaust valve would not open
causing it to backfire thru the carb during
I am putting in another
set of tappets from a different manufacturer.
Some say add zinc to prevent such occurrence
It can't hurt and every old cam follower (Lifter) I've seen had a worn/cupped surface on both ends. There's really no way to tell for sure how long the parts were used.
Up until a few years ago, most all oil from 197x had Zinc. I believe they are using a Boron complex now which should be better than Zinc. I agree that adding zinc probably won't improve wear--Only make your oil cost more.
What sort of engine and transmission assembly are you speaking about adding zinc?
No Oil Additives?
Jerry you must be pulling our legs on that comment! :-)
I know of at least one person that uses MMO in the gas and sometimes in the oil.
Some people insist that you should use STP at every oil change and others that say Motor Medic or Motor Honey is essential.
As for me - I'm cheap and trying to figure out how to get the guy that changes the oil in my wife's van to save it for my T.
Danny S: the sheared off adjusting bolt was due to improper hardening in a repro part - hardening made it too hard and brittle, so it sheared off. No oil could have prevented that - only a properly made part. And most of them are OK now, I think.
The sheared bolt head looked like it was
trapped for a time before it fell loose in
the valve galley, causing the exhaust valve
not to open at all. The sheared surface was
unevenly polished, with no sharp edge to be
found at all.
I agree with Roger K. of Sweden.... It is a
hardening/manufacturing defect. That is why I
am replacing all my lifters/cam followers to
another manufacturer. I am just wondering how
many others have and will suffer the same from a
poorly manufactured batch of bolts.
It was probably cracked in manufacture or in heat treat. The pounding of the valve just popped it off. To be a stickler, it was not "sheared", as there was no shearing forces acting on it in this application. Most likely it's just a fluke and rest of your tappet screws are probably o.k.
As Roger stated, no amount of zinc would prevent this.
This lifter wore out in less than a thousand miles. Bad oil? No. All the others were fine, and are still in the car. This one just failed to get hardened properly. It sometimes happens.
I know of a customer for that adjuster bolt!
Did the valve job yesterday and had another adj bolt
fail in a lifter and break just by touching it. Looks like a bad batch of little brittle bolts.
I am not going to read through all the threads that come up on search. However, a comment not often made, that may or may not be easily found on that search, but has been made a few times. I do disagree with the "can't hurt" on this point. It has not been proven to my knowledge. But has been suspected that zinc added to the oil may cause some of the difficult to diagnose problems with model T ignition. It IS conductive, and COULD cause trouble with either the magneto, or timer (if engine oil leaks into the timer).
There was a recent thread about the magneto field coil burning to ground, resulting in a total failure of the magneto. The car was run for awhile afterwards on battery. When the engine was torn down for a refresh, the burn was found, and a simple cleaning seemed to fix it (as I recall from a later update).
The cause of the burn was not determined for certain. It could have been iron debris, lining remnants, or anything that could electrically bridge a "near short". Once the near short is bridged, even for only a moment, the oil provides carbon which builds a carbon trail that usually will remain until it is physically removed. I have cleaned similar carbon trails out of a few field coils myself.
Lubricating oil itself will not cause a carbon trail. It requires some sort of additive or contaminant to start the short. Cotton (clean no, contaminated, maybe), iron debris, brass (some types of band linings used brass fibers), or zinc, could result in such a failure.
Every time I read the sage advice of "cleaning the timer" as a hopeful fix for a rough running engine? I know the advice is good. But I also wonder what is in the oil? All those successful cleanings must have bridged the gap with something. And the timer gaps are huge compared to the field coil with gaps of much less than a tenth of an inch.
This one of the more interesting articles on the function of ZDDP (zinc compounds) in oil. I've been running a high zinc full synthetic 10w-40 in my engine since it was rebuilt going on four years ago now with no ill effects to the magneto. What I can't say is if the film the article claims ZDDP leaves is electrically conductive or not. Wish that was addressed, but it wasn't. Anyways, it is still a good informative article from a reliable source.