Have you flattened a cam?

First of lets get the dislosure out of the way. There will always be many folks who have just replaced the cam and lifters, and went about thier merry way. That's great, but for the folks who want to do things right, here are some important tips. When tearing your engine down to check bearings, cylinder walls, piston skirts, etc, etc. Here are two areas often overlooked and taken for granted. The metal from the lobes went EVERWHERE the oil went or flowed. That means through EVERY oil galley and behind the cam bearings!!! So, those of you who are taking the advice of some of us traditional engine builders, please dont forget to remove ALL oil galley plugs ans especially knock out the cam bearings, I cant stress that enough. Dont forget to thoroghly clean pushrods if the oil flowed through them. If oil flowed through a oil tube to the top end, they must be cleaned and maybe a good time to replace that tube also. Dont forget the oil pump and pan, and all the little places around the cylinder head that collect oil. There are many threads on oils to use and supplements so you dont lose a cam to start with. Use the SEARCH feature Ryan has provided for us first.

 

I want to point out also, guys and gals that have a vintage engine with rockers arms operating on a hollow shaft or tube, this is another great place for contaminents to accumulate. An great and HAMB well known example would be the Hemi. They have plugs at the end of the rocker shaft that must be removed and the internals ofthe tubes cleaned thoroughly whether for a rebuild of if you lost some cam lobes.

 

You are absolutely correct. Flat cam lobe requires the engine must be completely disassembled and cleaned if it is expected to live for any length of time.

 

Yup. I didn't do that on the 454 in my 55 when the cam went out last time (2005), and somehow it's still running. I should know better. At least it has a roller in it now so I don't have to worry about it eating up cams quite so fast.

 

I have lost lobes/lifters on both flat-tappet and roller cams mid-season. cleaned 'em up as best I could, plugged another cam in and kept going. I never knew just how much BS I could get away with until I got involved in running in a couple season-long points chases. You end up doing a lot of shit that you normally just wouldn't do when missing race days starts to become critical. Even gone rounds filling a crack in a transmission case with copper-coat and pushing the car through the lanes. Short burnout, stage quick, so the fluid doesnt work its way out of the blanket when the starter can see it.

 

Been there, done that... had to buy a new engine kit and rebuild the darn thing again, only with a roller.

 

Brings back memories of the late 90s and early 2000s when everyone was wiping cams and couldn't figure out why... Glad that is pretty much behind us.

Good info, -Abone.

 

flamedabone...I'm a little uninformed on this I guess, but what was the issue around that time frame? I had a 283 and it wiped out a couple lobes on a cam, and still can't figure out why. With all of the cam swaps I've done over the years, it was the first one that did this. Any info?

 

Conventional wisdom is that it is the removal of beneficial additives and minerals in the newer configured engine oil. Zinc is one. A lot of people say to use diesel engine oil as it is still produced with a lot of the goodies the regular oil is now deficient in.

 

I discovered a bad cam in my 454 this winter, the cause of the failure will probably never be known. I beileve a complete teardown is necessary if you want the engine to live. My bearings were full of embedded metal particles and the oil pump had some obvious damage from ingesting debris. It was the only time this has happened in several dozen cam swaps and engine builds I've done. I guess it was bound to happen sometime.

FWIW the cam, lifters, timing chain, pushrods, pan and oil pump were replaced in the fix. Everything else was carefully cleaned and re-cleaned...

 

I flattened a few lobes on my 409. I thought I was being smart by putting shims under my valve springs to increase tension. Instead, the spring bottomed out before the valves were opened all the way. The result was bent pushrods and flattened lobes. The shims were removed and the cam replaced and everything was fine. It was in a '58 Biscayne which would pull 6,000 rpm with a 3.08 gears. This was flying in 1964.

 

X2....I too build race engines and every nook and cranny can hide fine metal shavings. Nuff said !!

 

Lucky3, behind those cam bearings are like bear traps, and It's nice that you agree, anywhere the oil goes, so does the trash. 03GMC, sorry to hear but you found out, the shims are just for establishing and or correcting the "installed height " of valve springs, they are not to be used for helping worn springs. The only thing you can do with sacked springs are replace them. Glad you have things worked out.

 

I sold an Iron Duke to a kid that didn't understand that it had a radical cam in it. He thought that it ran rough. Adjusted the timing to 0deg because it ran smoother. Then wanted his money back less than a 1000 miles later because it wouldn't run. Said the oil was grey and I sold him a bunk engine.

 

Been there , this is solid advice . If you happen to find yourself in this predicament , that blue workshop towel soaked in trans fluid works wonders for getting filings out of galleries and the like ...

 

One more question...it seems as though using a roller cam and lifters would eliminate the issue...having never used one, is this true? It seems to me that wiping out this type of set-up would be tougher to do. And I did use the zinc additive in the oil when I did the swap, and have heard that with older motors, because this has been removed from modern oil, it should be added at EVERY oil change (which I regularly do).

 

Yes with roller cams and lifters, additional ZDDP is not needed. Yes you need to add it with every change. Its not like a Z-MAX type of product which they claim goes into the metal pores or something like that. When you dump your oil, you dump your ZDDP.

 

Questionable at best. See my post on another "I dont need no stinking ZDDP" type thread about Mercruiser warranty issues with roller lifters...

 

17 yrs old was my first motor rebuild i wiped almost every lobe off the cam. i had no help, just a know it all friend that gave me bad advice when it came to adjusting the valves. tore the motor down and rebuilt it with help from a sympathetic machinist, motor still runs tits almost 18 yrs later. best education ever.

 

Wiped a lobe off a comp cam the very first time out with a new 468. Went home stuck in another new one,drained the oil,put magnets all over the pan and oil filter and ran it the rest of the season. However, when we took it apart in the fall it was UGLY inside. Piston skirts, cyl walls and a few bearings were all hurt. Last season the same thing happened only this time it was an Erson cam. That motor HAS to have 700 runs on it now and still runs fast. I know it's wrong to do but so far.......? P.S. I work for Valvoline Oil Co. so trust me it had huge amounts of zink during break in. I think it's just bad cam blanks industry wide.

 

Mike Jones said that a bunch of soft blanks made it into the market several years ago. I'll try to dredge up his original email...

 

Then how do you explain the tens of MILLIONS of cars around the WORLD with roller cams or roller followers who get by EVERYDAY without "high levels" ZDDP in thier oil, this should be very entertaining and amusing at the very least. I have friends, engineers at Mercruiser that I have raced with and against for decades, please enlighten us with your uh story. Then again its not really needed, not at all, I'm already bored.

 

Let's not forget the rocker pivots on Oldsmobile engines. Used to have them come into the dealership all the time with valve clatter. The standard procedure was to replace the pivots and flush the engine a couple times with Risoline.

 

I just read where comp cams is offering a nitriding option on their cams to help stop this problem. It is kind of pricey but if you ended up in BFE with a blown head gasket, water in the oil, and had to refill with something with low zdp for a while, it should get you by. The upcharge is also worth it to NOT wipe the cam on startup. Every little bit helps I guess.

 

Are you using a cam breakin procedure? Have the engine ready to run for 20- 30 minutes at no less than 2000 rpm. Start it up and bring the revs up and don't let the engine back to idle speed for any reason. If a cam is going to fail, it generally happens in the first few minutes. Some engine builders break in their new cams using light valve springs or remove the inner spring.
New cam requires new lifters. And new lifters require new cam. They must wear in together.

 

All current oils have ZDDP in them. Just lower levels than before the changes that were made in recent years. There is plenty in there for roller cam motors in the current oils, just not enough for flat tappet cams

Also remember that the early 90's time frame (or whenever it exactly was) when cams were falling flat like crazy was due in large part to faulty lifters. Most of the American manufacturers had stopped making lifters as the OE's were no longer using them and the off shore ones were junk. This was a much bigger problem than soft cam blanks

 

Does everybody remember Chevy 305 and 350 motors taking out exhaust lobes usually on cylinders 6 or 8 in the mid to late 70s? It usually occured at between 55-85 thousand miles regardless of the maintanance they received. Replaced dozens of them with the motor in the vehicle, pull the valve covers, back off rockers, pull timing cover,gears, cam, lifters, lube up new cam and lifters and reinstall everything. Obviosly change oil and send it out the door! Never had a come back, dad's truck a 1975 lost the cam in 1980 with 75,000 miles he bought a new one in 1988 and the 75 had 130,000 miles, it was still doing local courier work into the 90s. Cleanlyness is certainly very important but sometimes just getting the vehicle back on the road cheaply out weighs whole and often unnecessary engine kits. This was also in the days of good oil with zinc!

 

I lost 2 lobes on a comp cam in a chevy 327 stroker engine. The engine didn't have 15 miles on it when she started knockin. we pulled the engine and sent it back to the shop to have it gone back through. Bad cam material? Didn't break it in properly? Wrong oil? who knows. It was a pisser though. Did change to an Erson cam this time.

 

Actually Trad I used to have an SBC cam that I flattened with an angle grinder.

It was one that I used as a cam bearing ream for those times that the idiot that installed the cam bearings burred one. I knocked the lobes down to make it easier to slid in and out.

This is excellent advise by the way. You can get lucky once in a while I suppose atleast one of us has but you really need to pull any engine down at the very least for a general inspection and cleaning if you run anything through it be it cam or rocker or????

I pulled an engine down once that had a hydraulic lifter come apart. I do not know how it got there but a piece of the wire keeper for the lifter was loged in the oil pump.

 

Thanks Don, I understand and know all the oils have "SOME" ZDDP in them. I have said many times in other threads, how I read the MSDS, and read and understand the analysis. The levels are extremely low in modern oil. I'm sorry if you thought I meant "ZERO" ZDDP in the modern oil, I simply meant and I thought it was understood that levels are not the adequate for flat tappet cams and lifters in vintage tin any more. I never thought or meant that there wasn't "any" ZDDP in modern oils. I added the term " high levels" in my original post, so there is no misunderstanding. I have even posted before, several times, what is the actual needed ZDDP in Parts Per Million for folks here at the HAMB. Thank you Don.