Flat Tappet Motor Oil One More Time

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The antique design (through 1930's) engines with actual flat tappers that had wear problems now attributed to anything OHV were solid (not hydraulic) flat bottom lifters, and had splash/drip lubrication of lifter/cam. That means the cam lobe to follower bottom interface has no pressurized oil feed going there, through the cam. You will rarely find a design with hydraulic lifters that are not pressure fed, or that are actually dead flat.

The engines with the actual non hydraulic and non oil pressure fed (drip/splash only) cams with actual flat bottom followers generally will need cam/lifter replacement at anywhere from 30,000 to 50,000 miles, depending on driving style if the engine is in factory stock (low compression) configuration. Raising compression ratio or adding a supercharger will obviously aggravate this problem. Replacement cams eventually began using (literally) "fatter" cam lobes with more realistic profiles, and those would last much longer, and that added longevity was often attributed to some whiz bang oil.
 
Sure doesn't show that you are educated. Smart [censored] maybe, Educated, not so much. Yes cummins is still building flat tappet engines. One of the best engines ever built. No where did i state they asked for high ZDDP oil. but well, those who are educated know the higher ZDDP oils are beneficial to said engines.
 
Originally Posted By: silverbar
The engines with the actual non hydraulic and non oil pressure fed (drip/splash only) cams with actual flat bottom followers generally will need cam/lifter replacement at anywhere from 30,000 to 50,000 miles, depending on driving style if the engine is in factory stock (low compression) configuration. Raising compression ratio or adding a supercharger will obviously aggravate this problem. Replacement cams eventually began using (literally) "fatter" cam lobes with more realistic profiles, and those would last much longer, and that added longevity was often attributed to some whiz bang oil.


BMC made the B engine up into the 80s and the A engine up to the late 90s with exactly what you're describing-flat bottom solid tappets.

It's certainly not far fetched for one of those to make well over 100K miles, and usually the rings and bearings are shot before the cam.

Mine has close to 100K miles on it. I DID change the tappets, but that's mostly because I was doing some other work and along with it decided to upgrade to the lighter, more modern tappet/pushrod design introduced in 1973.

I will be changing the camshaft some time soon, but for performance reasons and not out of necessity.
 
Originally Posted By: bunnspecial
Originally Posted By: silverbar
The engines with the actual non hydraulic and non oil pressure fed (drip/splash only) cams with actual flat bottom followers generally will need cam/lifter replacement at anywhere from 30,000 to 50,000 miles, depending on driving style if the engine is in factory stock (low compression) configuration. Raising compression ratio or adding a supercharger will obviously aggravate this problem. Replacement cams eventually began using (literally) "fatter" cam lobes with more realistic profiles, and those would last much longer, and that added longevity was often attributed to some whiz bang oil.


BMC made the B engine up into the 80s and the A engine up to the late 90s with exactly what you're describing-flat bottom solid tappets.

It's certainly not far fetched for one of those to make well over 100K miles, and usually the rings and bearings are shot before the cam.

Mine has close to 100K miles on it. I DID change the tappets, but that's mostly because I was doing some other work and along with it decided to upgrade to the lighter, more modern tappet/pushrod design introduced in 1973.

I will be changing the camshaft some time soon, but for performance reasons and not out of necessity.


Sure bunnspecial, on point. The A and B engines go longer because by the late 50's even the British had started using better steel hardening for cams, and using wider and better designed cam lobes with pressurized oiling. They learned from the past. Look to the X engines before that, which were designed in the late 30's, and in stock form would be lucky to go 50K miles on a cam. Thing is, they reliably went that long because it was a good design. Like I said, replacement cams started coming along later for those X engines that lasted longer, and often people ignorantly attributed that later longevity to magical oil, when in fact it had nearly nothing to do with what oil was in there. And so the flat tappet myth was born.
 
What is it with these losers that keep coming back to this board to get their jollies by being a rude arrogant idiot? I really don’t understand it. I mean you’re going to get banned anyway, it’s just a matter of time. It even appears that that’s what you want. Does this give you some kind of weird pleasure?
 
This guy actually reminds me a whole lot of someone who pops onto the MG forum from time to time...perhaps it's a quite a small world, but the use of the phrase "flat tapper" and references to the MG X-type engine along with an obsession with tappets and valve clearance make me wonder.

BTW, I have a partially stripped B engine(18V) and a bare 18GA(3 main) block sitting in my garage. I don't know where the supposed pressurized oil for the cam comes from. The only oil sources are-primarily-what drains out of the rocker shaft and then down the pushrods(its only exit path) plus some splashing from the crankshaft/sump.

Plus, the last I heard, XPAG/XPEG engines were still wiping cam lobes left and right, some with a only a few thousand miles on them. I'm not overly plugged into the T-type world, but enough people are buying them that there are a few roller cam sets on the market that sell pretty well. I know of a few folks running roller cams in A and B engines, but they are pretty much one-off pieces.
 
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Originally Posted By: bunnspecial


BTW, I have a partially stripped B engine(18V) and a bare 18GA(3 main) block sitting in my garage. I don't know where the supposed pressurized oil for the cam comes from. The only oil sources are-primarily-what drains out of the rocker shaft and then down the pushrods(its only exit path) plus some splashing from the crankshaft/sump.


Exactly my point...
 
Hello,

I have seen BMC B Series engines in the 1960s do over 300k miles without cam/tappet issues
The lubricants in these cases were Castrol Castrolite 20w-20 - temperature rage -10c +28C
The A and B series engines were great and so was the C engine too

No so when the A engine derivative was put into the original first series Mini in 1959 - it was a 20W-50 viscosity or disaster and this at 1k OCIs. This was due to rapid oil degradation due to the integral transmission
 
Yes, those engines thrive on sludge. Best to never change oil in those engines if you lucky enough to find one that actually runs.
 
Originally Posted By: Scdevon
Originally Posted By: Building3
Even if his methodology is wrong, does his answer make sense? That there is more to preventing flat tappet cam wear than just zinc, or is it that zinc levels matter what other anti-wear chemicals may be in the oil?


This is what I always argue. A Pennzoil engineer (for example) could defend Pennzoil in a court of law that Pennzoil's additive package protects at least as well or better at, say, half the zinc level that oils had decades ago when you view the additive package in it's entirety.

If low zinc oils were fatal to flat tappets, wouldn't major oil companies place a warning label on their newer generations of oil to avoid a class action lawsuit from people using it in older cars? There are tens of millions of flat tappet cars still out there on the road. Toyota to this day still manufactures bucket and shim overhead cam engines, don't they? Buckets and shims are flat tappets in my book. It seems like all this obsession about zinc levels is a little overdone.


Bucket and shim is not flat tappet. A flat tappet is a spinning lifter riding on a tapered lobe. In truth, it is not flat, but must have a minuscule crown to work. In most USA flat tappet cams - the once that have failed, it is either the cam core hardness or the radial geometry and hardness of the lifter that was/is the problem.

OEM valve spring pressures can live comfortably at ~800 PPM of a well formulated ZDDP. Aftermarket performance valve trains may need considerably more ...

The OP's 289 and 440 are not suspect having poorly made cam sores or bad lifters as OEM parts. Both will run a zillion miles on any decent motor oil.

Yes, I'd try for a bit above average grade oil to ensure that motors in cars that are actually appreciating in value keep doing that. But these two motors are well understood, and neither is likely to fail a cam
smile.gif
 
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