Flat tappet Cam Failure theory's.

[dave1251]

I will cover one of many flat tappet cam failure theory's other than the lower ZDDP level's of PCMO'S. I chose not to discuss that theory because frankly I am bored of it although it could apply and you can not convince some people that this may not be the reason for cam failure I prefer to look at all possible factors because I have not seen cam failure in stock applications in even older cars that have flat tappet cams from the 60's and 70's using SL, SM, SN, GF-4 or GF-5 oils. Even though I will point another factor I will not dismiss this theory I just will not discuss it here. Enjoy my alternate theory below.

During 2004 the major flat tappet cam manufactures were
Hylift(Johnson),Eaton, Stanadyne, and Delphi(GM).

Hylift the major supplier of Johnson lifters and the aftermarket supplier such as Federal-Mogul well simply put went belly up. If you want to know why feel free to google hylift.

Eaton decided it no longer wanted to be in the flat-tappet business "very low volume no-one was buying flat-tappet cams" and it soldout to Stanadyne, which initially added no capacity and in fact shut Eaton's line down.

The other manufactures Delphi was still producing cams for GM and Stanadyne was focusing on other business.

With Hylift and Eaton out of the lifter business there was a flood of foreign aftermarket cams and often the foreign cams were manufactured with questionable metallurgy and an improper crown radius yet foreign cams were affordable and available. Of course during this time-line there was a major uptrend in flat-tappet failures.

I hope you enjoyed the read on a often forgotten factor on flat tappet cam failure. Please add other possible factors and comments but please do not included the lower ZDDP level theory that has been covered to death and beyond.

 

[1999nick]

What does your discussion of the manufacturers of flat tappet cams have to do with the failure in use of these cams?

 

[OVERKILL]

Basically he's saying the increase in flat tappet cam failures coincides with the influx of foreign cam cores, many of which probably came from China.

Walmart/Habour Freight cam cores became common, and an increase in failure rates went along with it.

 

[dave1251]

Overkill thanks, that is the reason why I wrote this. I also did this because honestly I want to point out the decrease of ZDDP may or may not be the only reason for the increase of flat tappet cam failure.

 

[JetStar]

Over the years I have read the same thing. Not only a cam core contribution, but compounded with lifters of questionable quality.

 

[doitmyself]

Quote:
I prefer to look at all possible factors because I have not seen cam failure in stock applications in even older cars that have flat tappet cams from the 60's and 70's using SL, SM, SN, GF-4 or GF-5 oils.


Thank you Dave. Are you confident that this idea holds true outside your circle of experience?

The impression I got from studying BITOG was that the problem manifested itself with mostly high pressure (springs) modded systems. You are adding that poor parts manufacturing may also be a contributing cause.

Hasn't anyone confirmed the parts quality issue?

 

[Kestas]

Has anybody reported what it was about the metallurgy that was deficient? Most tappets are chill cast iron - roughly 50% carbide at the face. It's not rocket science to produce these parts. But if anybody can screw up metallurgy, offshore facilities can.

 

[Kestas]

Another thought - I wonder how many of people who rebuild tappet engines, also make modifications to hop up the engine's output, such as installing more aggressive cams. I'll bet it's a lot.

[sarcasm] of course valvetrain failure can't be attributed to the fact that the rebuilder went ahead and redesigned the engine... it must be the oil! [/sarcasm]

 

[SteveSRT8]

^^^spot on the money.

I grew up in the flat tappet era, and I've seen many a lifter that was flat as a pancake from the box! Also seen many a bad cam, as in poor flame hardening or bad machining, or both. Then there's the break in procedure.

Careful inspection of all the parts will help you a bit, as the aftermarket is a bit sketchy in isolated instances.

 

[mechtech2]

Old V8s with flat tappets [actually convex radiused] wore a lot, even with old high ZDDP oils. The tappets always became concave and the cams worn.
Many new engines use bucket/tappets/lifters, with no rollers.
but with lighter loads, they exhibit almost no wear. This is with modern ZDDP weak oils.

Cam/lifter wear has nothing to do with foreign mfrs.

 

[Garak]

Originally Posted By: dave1251
With Hylift and Eaton out of the lifter business there was a flood of foreign aftermarket cams and often the foreign cams were manufactured with questionable metallurgy and an improper crown radius yet foreign cams were affordable and available. Of course during this time-line there was a major uptrend in flat-tappet failures.


I think your theory has definite merit. Even back in the Chevy small block days (with high ZDDP oil) there were major issues of excessive cam wear. All our fleet vehicles had the issue. Could they have been poorly sourced? An engine design issue?

With aftermarket cams, particularly from questionable sources, I would suggest that such issues become magnified. You take something like a small block Chevy, use a more aggressive cam that was poorly manufactured, and follow improper break in procedures, you shouldn't be surprised that there would be a high rate of failure.

 

[GMBoy]

I've never looked at it this way, by I can see some merit in what dave1251 is saying. When you consider the junk bearings and tools that come from offshore locations it sure does appear that a lot of their metalurgy is poor....so could the tappets.

 

[SteveSRT8]

I have had bad lifters right out of the box from almost every major mfgr in the US alone. Comp Cams, Crane, Lunati, etc. It doesn't matter where you buy them from, they should ALL be inspected and measured before install.

I am amazed at the trust of those who simply put the parts on right out of a box without careful checking. Metallurgy won't help you a bit if the lifter is flat in the carton!

 

[MarkM66]

Just had a comp xtreme 286 flat tappet cam go flat in a 468 BBC I built.

I built the engine years ago, and just got the car ready for the engine. I broke the engine in with 30 min of run time, @ 2000 rpm or so, plenty of zddp, but I skipped removing the inner valve springs. So I rolled the dice on that one. Still a major disappointment. Engine is pulled and coming back apart.

I'm done with flat tappet cams for life. Hyd. roller is going in it.

 

[dave1251]

Everyone thanks for your responses. This is what I was looking for! But to answer the question I can not verify from anything other than my experiences, but this is something I will keep a eye out for and update everyone.

 

[SteveSRT8]

Originally Posted By: MarkM66
I'm done with flat tappet cams for life. Hyd. roller is going in it.


A really sad story. Especially after the long journey!

A small investment in machining and better parts(roller) will pay off in better power numbers and HUGE driveability improvements.

You'll be amazed at how much lift you can have with a roller and yet get excellent manners.

Next hurdle? Fuel Injection!

 

[Propflux01]

Originally Posted By: MarkM66
Just had a comp xtreme 286 flat tappet cam go flat in a 468 BBC I built.

I built the engine years ago......

but I skipped removing the inner valve springs....


And you wonder why it went flat...

 

[Garak]

Originally Posted By: SteveSRT8
I am amazed at the trust of those who simply put the parts on right out of a box without careful checking. Metallurgy won't help you a bit if the lifter is flat in the carton!


That's important, too. Some don't pay enough attention to detail or simply don't know. Some are boy racers or DIYers, and as another poster pointed out, some simply roll the dice.

 

[rodinator1234]

MarkM66

Just out of curiosity how much spring pressure did you have? Over the nose and on the seat.

 

[SteveSRT8]

Originally Posted By: Garak
Originally Posted By: SteveSRT8
I am amazed at the trust of those who simply put the parts on right out of a box without careful checking. Metallurgy won't help you a bit if the lifter is flat in the carton!


That's important, too. Some don't pay enough attention to detail or simply don't know. Some are boy racers or DIYers, and as another poster pointed out, some simply roll the dice.


So true. I had the good fortune to be trained by a Royal Canadian Air Force helo mechanic, and fussy would not begin to describe his work ethic. We would sit and mike parts for a LONG time before we ever assembled anything!

A few minutes of careful work can save a lot of time down the road.