Camshaft Eater: What Am I Doing Wrong?
 

I can't figure this out. My truck eats camshafts.

I bought the truck in 1994. It was a cowboy special out of the state of Wyoming. 1970 sheet metal on a 1971 4x4 chassis. Wyoming and Minnesota disagree on how to mark such a beast on the title but I got that all straightened out and never looked back.

The truck had a 1978 4-bolt main 350 with poor oil pressure when I bought it. I put two or three camshafts in that engine. I figured it was the poor oil pressure and started getting the pieces together to build a 383.

The 383 happened when you still had to find an original 400 crank shaft but after they had pistons available to use your 350 rods. This all went together and was installed in the truck in late 2004. (Now a days you buy a complete rotating assembly and go from there).

Then three years ago this happened:
http://67-72chevytrucks.com/vboard/s...d.php?t=710954

Kids, no time, work, etc. It took me three years to pull the 383 apart while my truck limps along on a 307 I had laying around.

Sunday I pulled it apart only to find not one but TWO lobes on the cam were going flat!

I know oils don't have the flat tappet cam additive so I always used the $6/quart Valvoline "racing" oil.

This current flat cam only went 10,000 miles in the 15 years since the 383 build.

What am I doing wrong?

Oh. Since you guys like pictures I better add one. I did finish paint and body work. That only took 24 years.

Re: Camshaft Eater: What Am I Doing Wrong?
 

Did you hot tank it every time you put a new cam in it?

Re: Camshaft Eater: What Am I Doing Wrong?
 

I bet that valvoline doesn't have enough zinc in it. If it had that much trouble with cams, I would invest in a roller cam and never worry about it again.

Re: Camshaft Eater: What Am I Doing Wrong?
 

This^^^ Check the zinc content of that oil. Most oils no longer have the zinc that flat tappets need

Re: Camshaft Eater: What Am I Doing Wrong?
 

Yep... if the engine wasn't torn down and tanked, and then made sure the oil galleries are cleaned out... it's a recipe for cam failure.

When I had a cam wipe out, I was shocked at how much fine metal particles were trapped under the oil pan baffle. So EVERYTHING has to be cleaned out and new bearing put in.

...and use a zinc additive.

Gary

Re: Camshaft Eater: What Am I Doing Wrong?
 

If your cam is stock lift numbers or two steps over, like a RV cam I would suspect something other than the oil. I have run Valvoline VR-1 with a Comp Cams, one step over stock, for 80k now with no issues.

You could have Valve Springs that are too strong??? Or a cam that has not been Nitride Hardened like Comp does on their products.

I find it hard to believe your problem would be attributed to the oil as my research shows the VR-1 oil has a Film Strength of 100,000 psi. That stuff is specifically formulated for a flat tappet motor if I am correct.

Check here:https://540ratblog.wordpress.com/

I have posted this about 4 or 5 times so, I am really thinking you have something else going on with the Cam or Lifters. Brands matter, there is stuff marketed as high end product that will not stand up in today's world.

Re: Camshaft Eater: What Am I Doing Wrong?
 

10,000 miles in 15 years??? That's a lot of setting up dormant.. Given enough time, oil will drip off (or otherwise depart from) internal engine parts. During initial start up, the lifter faces and cam lobes are essentially dry, and considerable wear takes place before oil reaches these surfaces.. Weekly startups and short drives will help this situation..

Re: Camshaft Eater: What Am I Doing Wrong?
 

It could be related to spring pressure and valve adjustment. Too tight and ti is extra wear on the lifter and the lobe.

One of the other posts suggested parts selection, a well made lifter vs. a poorly made camshaft and the lifter will win over time. Check the lifters if the face is still flat then it may not be oil related as both the lifter and the cam should be worn.

If so I would check the oil gallery route.

The next would be geometry and set up. Taller cam without matching springs and matching push rod length may be an issue. If that is the case even if two lobes failed there should be some wear indication across the board.

I am a Comp Cams guy and we had a brand new engine eat a cam shaft once and we second guessed our selves up one side and down the other. Our local shop would not warranty the part as they put it on install and break in (which break in is a another possible point of potential failure, the majority of the damage done in the first ten minutes). Our local race shop owner sent it back to Comp Cams and they sent him a replacement. Never said what it was but said it was a 'factory defect'.

We were happy enough with the service so never dug any deeper as the true cause.

If all else checks out I would look into the break in. I have seen where break ins get interrupted by leaks or other issues and not get the true attention a break in deserves/requires.

Best of luck.

And I am on a 10 year project now that is just about ready to be painted. If 24 is the norm, I am ahead of the curve. LOL

Scott

Re: Camshaft Eater: What Am I Doing Wrong?
 

While your issue could be many many different things these are the most likely:

Engine Block: Back in the day mid 70s and up small block Chevys were notorious for cams going flat. What I found In the majority of these cases was core shift in the casting process and miss machined lifter bores. Before rebuilding any small block I would look for an untouched core that still had its original cam and lifters. Upon teardown I would carefully inspect the cam and lifter wear, then check to see if the lifter bores were properly centered in the casting ( looking for core shift) only about half of the blocks from that era will pass these tests and MoveOn to be rebuilt. You didn’t mention if you used the same block that gave you the initial trouble but your symptoms certainly point towards this.

Junk aftermarket Cam and lifters: I can’t really comment on where things stand today but I can tell you in the last 10 years there isn’t a single brand in the pool that isn’t of questionable quality. It’s a total crapshoot.

Dry starts: These trucks often sit for months and years at a time and every time the engine is fired up after that time period wear can occur for the couple seconds until enough oil is splashed in the lobe area of the cam.

Likely your issue is a combination of all of the above multiplied.

My thoughts on flat tappet camshafts and small block Chevys: there is absolutely no reason to put together any small block with a flat tappet cam anymore. Yes you can save a few bucks, it’s absolutely not worth it. With my experience over the last 10 years you have about a one in three chance of having some sort of a cam wear issue on a flat tappet rebuilt small block.

I read your attached post regarding the crankshaft problems. With everything you put on the table I would write off the 383 and just buy a 350 Vortec roller cam Long block from Jegs for $1500 and be done with it. The Vortec heads will make up the difference in torque over the 383 and the roller lifters will solve the flat cam issue forever.

Steve weim55 Colorado

Re: Camshaft Eater: What Am I Doing Wrong?
 

The flat tappet cam deal is a little complicated. I have wondered about how that mechanical invention came about.
There's a bunch of stuff that have to be in spec for everything to have a good life expectancy.

1. valve spring pressure has to be in line to keep the lifter on the cam, and not too much to put too much pressure on the lifter face. Stock cams are the best place for this. You go high RPM, and you need more spring pressure, AND the lifter gets more abuse, FASTER.

2. The clearance between the bottom of the valve spring retainer has to be adequate, AND you have to factor in space there for the valve stem seal(at the top of the valve guide). If the spring retainer hits the top of the valve guide, your cam goes flat, FAST!!!

3. The lifter HAS to rotate in the lifter bore. Not everyone has the understanding of how the flat tappet works. It spins in the lifter bore, and actually only rides on the back half (or so..) of the cam lobe. The lobe makes the lifter spin. As the lifter spins, it obviously rubs and creates friction (this is where the zinc is needed). IF, IF the lifter ever quits spinning, the lobe and lifter bottom start grinding each other up. You'd think that even with the lifter spinning, this would be the case...that's next...

4. The break in is very important, Factory flat tappet cams had no specific break in time in the engine (at least that's what I've been led to believe). It's amazing that different cam companies have different types of break in lube. Some actually RUN OFF the cam after sitting for a short period of time..Moly paste should be applied to the cam lobes and the bottoms of the lifters, using the minimum amount needed!

Remember that the lifter needs to spin in the lifter bore! If the cam is much more than stock, the cam manufacturer will recommend using the outer springs for break in.

The cam break in is tedious. Your timing needs to be set close, to fire up the engine and bring RPM's to 1800-2000 immediately, for 20-30 minutes!!! The carb needs to be one that you know will fire up and run immediately also. If you have to fiddle around to get the timing set and the carb adjusted with the engine barely running, this can have negative results the the lifters breaking in, the way you want...
All this said, the theory is to allow the lifters to make a wear pattern on the cam lobes, with as little wear as possible. When this occurs, the metal on the lifters and the cam lobe are being hardened, it's call work hardening. This initial pattern will stay essentially the same, for many miles.

The brand of lifters can make a difference. I only use Hylift Johnson lifters, regardless of cam make. THese are possibly the only, or one of a couple American made lifters. NONE of the cam folks use these, or sell them, they are more expensive, but not enough to make me buy another brand...

This info may not help anyone. I learned it all from my engine building buddy. It has not failed me, yet. There's just so many details in putting an engine together, most are not aware of...I could spew another 1000 words on this subjet, and NOT be done...

Re: Camshaft Eater: What Am I Doing Wrong?
 

Weim55 has some very valid points. The one is feel may be most pertinent for your engine is the core shift. I've seen many of these have the cam journal off center so much that rocker nuts are barely on the studs on one side of the engine

Re: Camshaft Eater: What Am I Doing Wrong?
 

This is the best post on this subject in my opinion..... You have to run the engine sustained for 20 to 30 minutes at 2000 rpm while watching for the thermostat to open puking water everywhere the whole time watching temps, oil pressure etc....who knows where the timing really is....keep that rpm up...oh crap, now I have to shut it down because it's overheating! Been there done that no doubt it' doable but better safe than sorry in my opinion!

Re: Camshaft Eater: What Am I Doing Wrong?
 

Had a big block years ago that did the same thing. I double checked everything and ran a brake cylinder hone through the lifter bores while flushing it with solvent. Cleaned the block and reassembled. I did not have an issue after that.

Re: Camshaft Eater: What Am I Doing Wrong?
 

I'm with these guys. I doubt it's clogged oil passages since we are talking about two different engines, basically. I'd think when you built the 383 the block was hot tanked. It's not the oil. I'm sure of that. I have never used an additive and have never wiped a cam. 10k miles in 15 years is not uncommon in the classic vehicle world. My trucks sit for months at a time, again, never wiped a cam. I would think the valve guides would go before the cam from lack of lube. My '72 sat for a year and a half a couple years ago due to a broken plug in the head. New heads, same cam, second truck for that engine I rebuilt in '91. It's in this truck because it was just sitting in the other waiting restoration. Been running it in this truck 15 years. I use Castrol GTX

Re: Camshaft Eater: What Am I Doing Wrong?
 

I'm still at a loss for what happened here.
The camshaft was a Comp Cams 12-231-2. Nothing radical. I used the factory service manual, like I always do, when setting the valves.

It was 15 years ago but I remember following the Comp Cams recommended break in to a T. I even rigged up a tachometer because I hadn't yet installed one in the truck. It was something like 2000 rpms for 20 minutes. Puking 50/50 all over my shop floor. Running back and forth between the oil pressure gauge in the cab and the drain pan under the radiator. I primed the engine before startup with a priming "tool" I made out of one of my many old points distributors.

For sure the tired old 350 didn't get hot tanked between cams but the 383 was a fresh rebuild.

The block I used for the 383 was a 350 out of a 1971 Monte Carlo that I personally ran up to 174,xxx miles before the Minnesota road salt won. That engine didn't eat a cam in all that time unless somebody did it before I owned it before 11x,xxx miles. The only thing I remember doing to that stock 350 was pull the intake because the passage under the carburetor carboned up which screwed up the bimetallic strip that worked the choke. (All my small blocks from that vintage got that job at one time or another).

Since the tick I was hearing was the camshaft and not the crank keyway, I have half a mind to slap another cam in it for $200 plus the cost of a gasket set, reuse the stud I made for the harmonic damper bolt, and put another 15 years and 10,000 miles on it.

I'm so gun shy from flat cams that I put the two-piece timing chain cover on the 383 that Edelbrock makes so I could swap out cams easier.

Regarding not starting it very often, the truck actually gets used quite a bit. However in the winter I don't drive it on the roads due to salt. I plow my driveway (idle idle idle idle push idle idle idle) and drive it out to my fish house on the lake (idle idle idle stop fish idle idle idle home).

Crap the 307 that is in there now wasn't started for 15 years. I put it in the truck, changed the oil and filter, and put 777.7 miles on it with no cam going flat in that. (That is a real number. I just got out my log and subtracted odometer from when I put it in there from when I last filled up on 10 May. Funny). FWIW, this 307 is on its third vehicle. My 1972 Chevelle, I loaned it to my sister for a few years while she ran it in a 1977 Impala, now my truck.

Regarding core shift. Except on these pages I have never heard of core shift. In 35 years of owning small block chevys and working on them I have never witnessed core shift. With 174,xxx miles on the 350 before I turned it into a 383, I doubt I've seen it yet.

Still stumped.

And yes. Today I'd start with a roller 350 like the one tucked away in the corner of my shop from a 1999 Suburban that I ended up with after some horse trading. I got it for nothing. It had a knock that I suspect was from a piece of dirt knocked loose after a plastic intake manifold reseal job the guy had done prior to the knock. I guess that is common in those engines.

Given unlimited time and resources, I'd turn that roller 350 into a 383 or just rebuild it as is. But I also have to stay married.

Re: Camshaft Eater: What Am I Doing Wrong?
 

I really doubt it's the break in procedure... usually when one fails from improper break in it happens QUICK. I'm talking within several hundred miles.

My guess would be that the valves were gunked up from sitting and stuck when you first started it. Even if you used it frequently, the winter driving behavior you described can cause one to gunk up pretty quickly. If it's a stock engine, it usually just bends pushrods. If you have a built engine and hardened or chromoly pushrods then it can damage the lifters or destroy a cam. "short tripping" can also cause the lifters to stick in the bores. If the lifters aren't spinning they will grind a lobe off very quickly. I've personally fought this with a Ford Falcon that sat for years.

There's also a fair chance that the cam was just bad. Even 15 years ago, the quality of aftermarket parts was starting to wane. I've seen cams from huge brand names (comp, lunati, etc) that were not case hardened deep enough and wiped a lobe in short order. When they harden a camshaft, they typically induction harden it and only do the lobes and journal surfaces... This is a selective process and used to be done by hand (probably still is). I had a comp cam years ago that they missed one of the lobes when hardening and it was completely soft right out of the box.

I'd flush the block out and slap a cam and lifter kit in it and keep on trucking.

Re: Camshaft Eater: What Am I Doing Wrong?
 

mrein3, you haven't said anything about the springs you used. I've made the spring mistake myself before by assuming stock springs will work with a small cam. That's not always the case. Did you use springs that matched the cam requirements?

Re: Camshaft Eater: What Am I Doing Wrong?
 

All good info above...Anytime a cam lobe gets wiped off the motor needs to be dismantled and thoroughly cleaned or your flirting with disaster. You indicated the 383 was not jet washed (hot tanked) before reassembly, bad ju ju. The break in oil is critical, just as critical as the cam installation lube used. Theres only one I trust and its not that red karo syrup, it's this stuff, "Isky Rev Lube" https://www.summitracing.com/parts/i...iABEgJR3_D_BwE And even it with break in oil will not protect against fleck that got left behind from a previous failure. Whoever brought up the 15 year old cam brought up a good point, there was a time about and around 15 years ago when cams were failing with Comp and Crane as well as other aftermarket flat tappet cam manufacturers. 68Gold/white pretty well covered it, anytime I break in a cam I use Isky's rev lube and NEW lifters. New lifters are critical for a new cam break in because no two or more lifter and cam lobe surfaces ever wear the same as described in a previous post. The cam lobes get oiled by what the crank slings up and the windage in the pan, that's why varying rpm from 2000 to 2500 is recommended. Varying rpm varies the splash pattern thus oiling every square inch of that cam. Immediately following the break in, or very shortly there after, drain and inspect the oil as well as install a new oil filter because there's no better way to check the break in oil than by cutting that oil filter open and inspecting the folds in the filter paper. Good oil rich in ZDDP (zinc) is getting harder to find and can be expensive as well. Ive used Rotella T for years as well as Delo 400, I also use Mag-1, Mag-1 has one of the highest ZDDP PPM ratings and is very reasonably priced as well. Until you do a complete tear down and cleaning, nothing will work. You may be money ahead going with a new roller motor like an L31 and put the old stroker out to pasture...Good luck

Re: Camshaft Eater: What Am I Doing Wrong?
 

As someone else said I would go with a roller cam and not look back.

Re: Camshaft Eater: What Am I Doing Wrong?
 

A stock truck would not have done this if let sit for so long. Guessing mis matched components.

If you stay with the Flat Tappet design I would be inclined to try these:https://www.howardscams.com/products...rs-accessories

Look for the EDM hole style.

Re: Camshaft Eater: What Am I Doing Wrong?
 

Wouldn't particles worn off the cam affect the softer bearings as well? Didn't the cam being worn excessively and rapidly cause the particles in the first place, if it is clogged passages? All this seems to me to be possible issues but the effect not the cause.

Since total tear down is warranted to assure clear passages, might be a good time to move to that engine in the corner... if you think you can sleep at night never knowing just what caused the issue :cool:

Re: Camshaft Eater: What Am I Doing Wrong?
 

That's my problem. I'm a curious guy.

The only thing that makes sense to me right now is a defective camshaft. This fresh rebuild was to overcome cams going out.

I will say, except for what I may do with this project, I'll never build a flat tappet cam engine again. (I know, never say never).