Technical Flat tappet cam failures

Looking to get some real world numbers on who has had a cam failure after a rebuild or during/after the break in process.

If you did ruin your engine, what did you find to be the root cause, what did you have to replace?


I had a 302 with a 331 stroker kit eat a Comp cam, zinc additive, break-in oil, assembly lube used. I have built a couple dozen engines, I was an ASE Master tech/Advanced level tech so this isn't my first rodeo. This is my first engine failure (sucks because its my engine that messed my track record up)

I have a list of things that are bad, need to be replaced, and things I will do different when I re-redo my engine.

Ill save my specifics until I get some responses.

 

Wiped out two Comp Cams flat tappet big chevy. This was in two different engines and both times it happened in the garage. Replaced each one with the exact same cam and the exact same procedure and both have been fine since. I think its a crap shoot! On the first one we just drained the oil replaced the cam and stuck powerful magnets on the pan and oil filter. When we took it apart at the end of the racing season it was UGLY! Lots of scuffing on the skirts and cyl walls. Still ran good though.

 

b block Chev. Wiped out lobes even with Zinc additive. Crapped out the engine with particles. Started all over and that time it ran ok. ??????????

 

I pay Comp to re-surface harden my new cams after grinding. I think it's like $50

 

2001 was the last time it happened to me, I've been putting hydraulic rollers in the BBCs since then.

 

Back in the 80s and 90s there was a lot of talk about bad cam blanks, oil, etc. Even the factory cams were failing (but over time, not at brake-in). I took a Ford 400 apart with only 30 or 40K miles on it and the cam lobes were flat. I know a lot of Chevys had issues also.

 

if you mess with sbc's your well aquanted with flat cam's!

 

Never had an issue with flat tappet. Solid roller w/ big lift on the other hand... not enough oil splash to live too long on the street I've found. Idle rpm's don't lube them enough. Best left to the track IMO.

 

Last spring installed Edelbrock RPM cam and lifters in a SBF. Used Rotella T and Comp zinc additive. Didn't wipe out the cam, but an unbelievable amount of grit was in oil and filter after initial run.

I was tempted (and I think it's a good idea) to break-in flat tappet cams with light duty valve springs.

 

Mike 51 Merc just touched on something that most miss or won't admit too. In Comp's break in instructions, there is a phrase hidden that says something like, "If you are using dual springs, remove one of the pair". Now, that isn't the direct quote, but it is the gist of what they are trying to say. I believe they want you to pull the inner springs, but it's been a bit and I can't remember. I thought this sounded like a bunch of work when I first put my Plymouth's rumpity Chrysler small block together, so I didn't... Flat cam city a few months later. Went through the whole thing again, did the single spring deal, broke it all in, 90,000 miles... Follow the directions, even when it's work.

 

Besides dual springs, the other issue is that a lot of springs today are designed for roller lifters and have higher spring rates than flat tappet springs.

 

Around 2004 my GMC 302 engine lost a few lobes on a reground performance cam after about 500 miles. It was the ZDDP oil problem .I totally dissembled the engine and found metal shit in all the bearings...Cleaned the engine,new bearing and rings..

 

And that engine now has eighty thousand (counting the time when you had it) miles on it. I'm still using the Valvoline 20-50 racing oil in it.

 

2 cams in the same motor 15 min of running third cam ok used different oil and GM lifters had to disassemble and clean each time flat tappet solid lifter cams now i only use Brad Penn

 

I've never had a failure back when we used flat tappet cams. I never bothered with break in. The cams we used usually came with assembly lube or we got a can from a GM dealer. We often used the cam and lifters in more than one engine. In the early 70s we could get a 327 with a bad cam from the salvage yard that sponsored us. Those 327 and 307 engines had factory hydraulic lifter camshafts that had one lobe that wasn't properly hardened but they still lasted about 50,000 miles before the problem showed up.

In my opinion, the break in procedure and oil additives are just a smokescreen to cover poor quality control. It is either a poorly hardened camshaft or lifters. Cams and lifters should be checked for hardness.

 

I never had a cam issue until the late 80s. From what I read at the time Chevy factory cams were having a major cam failure issue, but Ford was also having some problems.

 

Both of mine were within the last 10 years. My brother in law lost one in his 383 sbc as well during this period. I work for Valvoline Oil so believe me, we buried them in zinc. It was/is a manufacturing problem I think. We had the replacement cam for the 383 treated and I will pay the extra from now on to get that done.

 

I think a lot of it has to do with the hardness(or lack thereof)differential between cam lobes and lifter surfaces.I recall having that problem in 57-58 Oldsmobiles wiping out cam lobes in a relatively short period of time.I must have replaced a dozen or so with that problem and it was almost always the lobes that wore out although I did have one or two that concaved the lifters.Seems whenever there is a metal incompatibility problem this occurs and not just in engines.

 

Stuck a comp 268h in a 350 a few months ago and was scared shitless I was going to wipe it out but I followed all the instructions, used the Comp lube as well as the break-in additive and all was well for the 1500 miles I put on it before sale to the new owner. The 268h is a pretty mild cam and I used the stock springs which probably helped. Also added an extra quart of oil for break-in just to splash a little more on the cam.

 

I own a auto supply & grew up in a full service machine shop & I have seen countless failures after 2004 due to I believe oils changing and possible the nitride issue. I still run open "a" dirt mods & choose to break my comp solid .597 .600 lift cams in with VR1 valvoline , comp 159 red moly & gobs of black engine assembly moly assembly lube on all surfaces with passage ways clear. But I also invested in a Howard's cam s 1:2 ratio break in rollers rockers for extra insurance because I still got to say some cams may not be nitrite treated deeply. Many assemblies & zero failures. I can't count on both hands though how many customers who have no idea how to properly set valves either hyd it solids & come in with wiped out lobes, And I've seen even a few builders who possibly got a faulty cam grind. Ask for the nitride & overdo the oil with zinc thing & you'll probably be alright. Installed spring height & coil bind are paramount too. Nothing like the sickness of metallic particles gliding themselves through all the oil galleries of your rides innerds!

 

Just broke in a 327 with a comp solid lifter cam with the edm hole in the lifter face using isky rev lube, brad penn break in oil. The inner springs were removed as well. I was really worried but everything went well. I figure the edm hole is cheap insurance.


Posted using the Full Custom H.A.M.B. App!

 

And.......for a lot of us I wonder if we got one of the "problem" cams that were stock piled in the performance warehouse somewhere. What else could explain one cam fails while the replacement one doesn't?

 

Larry,the replacement was a NOS cam reground by Lazer Cams. It's a .005 "tight lash" fast lift modified from their short track design. Inline "experts" told me the cam and 1/16 inch rings would be gone in 20,000 miles.

 

Have had a comp, thumper in my 302 for 4 years and prolly 10k miles no problems.............yet

 

There have been a number of lobe failures on hydraulic and flat tappet cams with the most prominent cause being faulty heat treat. The other is the use of the wrong (newer) oils that have reduced anti ware additives that coat the precious metals in catalytic converters.

 

So I have to ask what break in procedure you are using when you build a new engine (install a new cam)?
In the past, on first startup I have run the cam in at 3000+ rpm for the first 20 minits, change oil and filter and drive it ... never had a problem ... oh yeah lots of moly lube on assembly. just my 2 cents.

 

My 1.5 cents: Never had an issue with early failures. People here talking about splash oil and such. The main thing is the loading at the cam/lifter interface while the two surfaces get "acquainted". Using low load springs or low ratio rockers is a great way to do it, I never bothered though. Break-in rpm should be 2000-2200 rpm, not 3000 as posted above. If you were to measure pushrod load in the engine at various speeds (as I have) you would see that the loads are at their minimum around 2000 rpm. Below that and you have high nose loads from the spring. Above that and the peak loads from the opening and closing accels of the cam start to dominate. Around 2000, the two almost balance out and give you a relatively low smooth loading across the entire lift event, lower than any other engine speed. I will say this is true for all engines, but I expect there are some oddball exceptions. If the cam fails after a successful break-in, say after 10k miles or so, that's usually due to improper heat treatment of cam, lifter, or both.

 

Have any of you guys tried the Racer Brown composite lifters there clam is no more flat cams you can use them on any cam and swap them from lobe to lobe. Kinda pricey but if you figure you have to rebuild your engine again after a cam fails maybe there not so bad.

 

Watch this video it my help


Posted using the Full Custom H.A.M.B. App!

 

Usually---Cam isnt hardened!! treated-as should be done -in the old days - all were heat traeted & had some treatment done or they would go bad!! No excuse for a cam going bad today -if they do its directly the mfg's fault!! They missed something in the proper process!! I have seen some used lifters that caused damage -thats never to be done -used lifters!! Other than that -maybe excess spring pressures!!