Here is a question for the flat tappet cam guys....

[Kern Dog]

Most of us have heard of the increase in flat tappet camshaft and lifter failures over the last 20 years. Some of us have actually had it happen, even more than once.
I have. FOUR times too.
The blame has never been able to be attributed to one issue but is often spread around a few things. The reduction in the Zinc in the oil, stiff valvesprings, too little taper in the lobes or the lifters, improper break in, etc.
I've read that extended idling is bad since the cam relies on splash oiling from the rods spinning and spitting oil past the bearings. This is the reason why during camshaft break in, the RPMs need to be above 2000 to properly supply oil to the lobes.
Here is the question....
Once the cam is broken in, what harm is there in idling? The engine is under no load and there still is some oil being thrown around.
What about when you're rolling down the road and the RPMs are under 2000 RPMs? People with overdrive transmissions can be rolling down the road in 5th gear and be under 2000 RPMs for a few hours at a time. I do. I have a 3.55 axle gear and a .64 overdrive with a 26" tire.
I was out for a drive today and as I saw 1500 RPMs, I wondered if it could be doing harm.
There is a roller cam on the shelf that I intend to swap in over the winter but this issue of low engine speed at cruise has me curious.

 

[Strato58]

Do you think there is any credence to this QS oil being excellent for a flat tappet engine? And possibly break in procedures being done improperly thinking it was the way to go for all these years? Is the oils high film strength a reality? Its amazingly high in PSI. Maybe this blog shouldn't be poo pooed as much as it has.
https://540ratblog.wordpress.com/2013/06/20/motor-oil-wear-test-ranking/

 

[493 Mike]

Iron surfaces "work harden" with time so that will most likely explain why after a break in period cam material can withstand lower oiling conditions and survive.
Mike

 

[Ray70Chrg]

I've read, here on site, that excessive idling is not good but that was intended to mean 700-800 rpm idle and then turning the engine off. Like you stated 2000 rpm long hauls at 70-75 mph are common and have had no ill effects on my cars.

 

[Gunner1]

I worked for a large engine builder. We had 3 wet spin stations. Every long and short block got hooked up to a warm 45psi oil supply and spun at 800 rpm. We adjusted valves and checked compression I can tell you that without an oil pan or intake the amount of oil spun up on the cam was amazing.

 

[Geoff 2]

I see no harm in idling. It [ wear of lobe & lifter surface ] is about the amount of time that the two parts are in contact. Taxis can spend a lot of time idling at the taxi rank, yet the engines are known for long life.

 

[451Mopar]

I never had a cam go flat until after they changed to the API SL standard in 2001. They already had started lowering ZDDP levels in 1996 to 1,000 ppm of ZDDP (API SJ), but I don't recall having issues until the new SL which was still 1,000 ppm ZDDP, but something else changed, maybe deposit control? maybe more detergent in the oil?
When I put the 360 in the Coronet, I will be using the Driven Hot Rod 10w-40 oil.

 

[66 Sat]

I think it's worse with older carburetted cars than modern computer controlled engines. Fuel wash from rich idle mixtures, diluting the oil.
I don't like idling mine when cold either. The idle rpm is lower and the oil is thicker so I reckon the oil flow will be less.

 

[Darter6]

Back in the 60's-70's Cop Cars would idle for hours even days without being turned off. (before roller cams were standard) Officers I knew said sometimes cars would run 72 hours or more not being turned off during shift changes,fueling etc.
That said, yes quality was better back then . This is a interesting debate.

 

[threewood]

Iron surfaces "work harden" with time so that will most likely explain why after a break in period cam material can withstand lower oiling conditions and survive.
Mike

I tend to believe this theory. But even idling, the crank is splashing oil all over the place.

My last flat tappet cam, a Hughes grind, had most of the lobe tops polished off and one polished down and that cam was idled quite ofter. It didn't have the best break in either, but it had a steady diet of Gibbs Driven Hot Rod oil. Hopefully my new Hughes cam (textbook break in, used springs, Gibbs HR oil) lasts longer.

 

[496 polara]

While oil plays a role I think there are many available out there that remove that from being the problem. I believe having the lifters checked before running them for correct taper is the single biggest issue.Throw in too much spring pressure on break in and you have a recipe for failure.

 

[moparedtn]

The underlying thing with this issue to me is simple:
- For decades, we didn't hear (or experience) multitudes of cam failures in engines, rebuilt or otherwise.
Cams (and lifters) were made of certain metals (and were machined a certain way); oil was made a certain
way (all dino, of course).
Rebuilt engines were broken in the same way for the most part, too.
True?

Now...
- Can't hardly be in the hobby without hearing (and/or experiencing) about cam failures these days.

So...
- What changed? Manufacturing? Oil? Building processes?

Point is: Something changed to upset the apple cart - perhaps several things changed - but logic would say
when you are honest enough to point the finger at what actually changed in the process, you honestly
answered the question.