Technical SBC Bad cam during run-in - Advise needed :)

Hey everyone,

I have recently had my SBC (approx 1972, 350cui, mild cam, roller rockers, approx 300hp) freshened up, the freshen up included:
- Replacing cam and crank bearings (pistons were left dangling in block as rings and bores were good).
- Replacing Lifters and push rods (Hydraulic flat tappet).
- New valve guides.
- Head and was block skimmed.
- Carby rebuild.
- And new gaskets all round.

Everything else was re-used including: Cam (had cleaned), Crank (Had cleaned), pistons, rings, conrods, roller rockers, distributor although everything was cleaned and checked.
There was also an issue with a threaded head bolt that we had to heli-coil in the block (was #11 bolt in tightening order) nearest cyl #7.
The bolt torqued up perfectly and hasn't traveled loose at all, I simply just thought I'd state it.

The motor had its initial run in procedure done and then traveled approx 17miles so in total has a max of 2 hours run time.

The problem is I have badly worn 2 cam lobes and lifters, the culprits are cly #7 Exhaust and cyl #5 Intake, I find this very weird to be right next to the troubled head bolt... although I checked torque specs again multiple times and it doesn't seem to have traveled at all.

The worn lobes are really quite bad to the point lifter(cyl #7) is dented in so bad it has a hole at the bottom and cyl #5 isn't much better in total both valves have lost about 6-8mm of lift. The motor is currently still in the car as removing it from its current application is an absolute B**** that I'd rather not do AGAIN...

Also the sump to timing cover gasket got damaged while removing the timing chain cover.

My main questions are:
- How far do I need to drop the sump to replace the sump to timing chain cover gasket? and can I reuse the other sump gaskets or do I need to replace all again.
- Should I tear the whole motor down to clean it up and replace all the bearings again (I REALLY don't want to!) or could I get away with running some oil through it to clean it up or something?
- Is there any pointers or advise that could be given to help avoiding damaging anything again?

Ultimately I'd like to keep the motor in the car, clean it all up replace the cam and ALL the lifters and pushrods, Obviously I'd replace all the gaskets of things I have removed: intake mani, carb, fuel pump, water pump, timing chain cover and sump to timing cover. would anyone recommend against that?

Any help is greatly appreciated.

 

Don't be kidding yourself, you know you need to take the engine out and do a complete tear down.

 

New lifters? Or did you use the old ones. If you did and they didn't go back on the same cam love it is instant death. All of that metal from the cam and lifters is all over the inside of the motor. Tear it down ... Yes, pistons too... And have it all cleaned.

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Like he said and also be sure to use a zinc additive in your break in oil.

 

I did one recently and I have never had a FT cam failure. I use lots of assembly lube, like the Permatex stuff a lot. I adjust the lifters on the conservative side, can be adjusted after break in. Pre-oil the crap out of it until oil is present at all rockers. Use a high ZDDP oil. I use Valvoline 10W-30 VR1. Multi-grade oil will circulate fast. I added a bottle of Comp Cams break in additive. Then follow what the cam maker's directions say.

 

Its very importiant that lifters remain on the same lobes. Also any new cam needs breaking in. You need to run the engine at 3000 rpm for thirty minutes when first starting it to break in the cam. A good practice is to use a soft low pressure valve spring during break in. and change to the stiffer springs afterward.

 

I see a lot of concerns here myself. "Pistons left dangling" then "skimmed the block". How in t he world did you get the block clean?
NEVER put new/used flat tappet cam parts together.
The machining for the heli-coil may have put debris in the area to accelerate your failure if it wasn't properly cleaned. Again, the heli-coil isn't the problem, it's the cleaning after installation that would worry me.

Strip it down to a bare block. new cam and lifters properly broken in. Clean everything within an inch of it's life then do it again. If you change a flat tappet cam, change the lifters. If you re-use a flat tappet cam, keep the original lifters in their original order.

Need to blow it clear apart and clean it. Bearings will probably be toast as well, possible the oil pump. You now have metal thrghout the entire engine to deal with.

JMO,
SPark

 

My friend had a engine rebuilt for his car and the builder he used will only guarantee the engine if he is present at the start-up. He checked our installation it all over and gave it his blessing. It started up and within a couple of minutes of running at 2000 RPM and with plenty of oil pressure, the cam wiped out. Out came the engine, went back to the shop, torn down , cleaned and EVERYTHING checked and a new cam installed.

A week or two later, we repeated the installation & start-up and the engine ran great and is still running great, 10-years later. Sometimes, things just happen and you have to deal with it. Having a stand-up guy with a lot of engine building experience doing the work, is a major plus.

 

No zinc in oil will cause lifer failure on new cam / lifters @ start up . now complete tear down & cleaning is required , zinc is required in all flat tappet and solid cams

 

This engine got a used cam and new lifters. All the recommendations for what do to with a new cam and new lifters, are not real helpful to figure out what happened here...but are important for the next time you start it up, after you completely take it apart and clean everything, and replace the rings, cam, lifters, gaskets, and whatever other parts need replacing. (inspect the bearings, etc carefully)

What went wrong? you used new lifters on a used cam.

 

For the price of a new cam, the engine shit the bed. Just bad juju to even think about. These days I'm pretty anal and OCD when it comes to new engine assembly.

 

Just my 2 cents here . what I see happening a lot is someone puts an engine together and then cranks and cranks trying to get the timing set ,the lifters set ect. The lube is pretty much gone from the the cam by then. Also most engines I see going together are not CLEAN , taking it to a car wash doesn't mean its clean.

 

When you tear it down, make sure you clean the oil galleys as well. And don't forget to replace the cam bearings too.

 

^^^ This.

It was a crap shoot, it might've worked, lot's of people have gotten away with it over the decades, but this time it didn't. Everyone knows the cam/lifter interface is the most critical on a new or rebuilt engine, and the most common to fail. As soon as I read that the pistons were left dangling, that was a bad sign. Hey, sometimes we get away with cheating and taking short cuts, sometimes it comes back to bite us in the butt, this time it bit.

 

Difficult to tell what happened. The cam was apparently good as it was tested. If you used assembly lube on the cam and lifters and pumped the lifters up, I suspect bad lifters. To wear that deeply into a lifter in 2 hours I suspect a soft metal in the lifter. I've replaced hydraulic lifters without replacing a cam when lifters started clattering and didn't have any problems.

I don't think the manufacturers had any break in when first starting an engine. I suspect most of them started the first time on the assembly line. Maybe there is someone on the HAMB that worked in an engine plant. I toured the St Paul Ford plant in 1971 and they put oil and transmission fluid in at the end of the assembly line. They raced cars off the assembly line to the parking lot.

 

Just think of all time you saved the first go around. The second time will go quicker

 

A cam and lifter failure can happen in a minute or two, sometimes faster if the springs are stout.
When assembling the engine and setting the valves ( if adjustment is needed ), watch for lifter rotation. If they do not rotate, you can wipe out the cam really quickly. Very last step before intake goes on, add more cam break-in grease to lobes you can get to, you just cannot have to much on a new install. Only rotate the engine enough to get it together, prime oil system with a drill, NOT the starter.
Have the carburetor full of fuel, and have the timing set close enough to fire. Cranking for long periods of time with a high lift cam and strong springs, can wipe out a cam before it even starts if not lubricated properly. Any break-in procedure that happened before 2007-2008 no longer applies! Oils are different, cam grinds are much different, and metal quality is different.

Joe

 

How was the cam determined to be good enough for re-use?

Got any pictures of the lobes in question before being put back in the engine, and now that they have failed?

 

I would bet it was cheap lifters..I have seen them wear and pound all to hell in ten minutes of idle time on a new cam...

 

I set up everything with the engine on the stand first. This way it gets lubed, the distributor is in right. Timing marks are easy to see, etc. Then I drop it in the car. My last one fired immediately and we had it going for the cam break-in quickly.

 

what Squirrel said. I wonder if the other people who answered even read the post.???

 

GM used to fire the engines on LP before they where ever installed in a vehicle. They had a big air powered impact that spun the engine from the front balancer. Im certain they had oil in the engines during the test fire. The thing is used to be no matter what camshaft you had if it was A usa cam. The core came from Crane. They supplied blanks to everyone. The factory closed and the equiptment went overseas. So no matter who machines the cam. If you don't start out with a quality core what you wind up with is inferior. Quality parts come from new steel and cast not recycled rusty scrap.

 

I've had a lifter or two go bad, and just replaced the lifters with no problems....any thoughts on that?
It was on a '70 340 Mopar
Just asking for my knowledge, not starting any crap or argument

 

47 years ago the camshafts & lifters where better and harder surface than they are today. And yours was a factory setup. Aftermarket cams and stiff springs its iffy when everything is up to par. Ive got a old 283 with weak valve springs on a stand. I will install a new cam in it fire it up and break in the cam. Then swap the csam into a new engine. Makinh certain to keep the lifters on the lobes that where run in on.

 

That sounds like a good idea....I always wondered about breaking in a new cam at 2,000-3,000 RPM in a new engine , what it would do with the rings,bearings etc.
My experience in breaking in new engines is mostly 2 cycle stuff where they say to idle for a time, then part throttle with short bursts, before you run at top RPM.
One of my old mentors that used to race Merc outboards told me that if they broke them in that way, they would get better rpms and longevity out of their race engines

 

Exactly what Squirrel said. Cause:? Bad lifters

 

Think of hardened sand going through your oiling system, now would you like to not tear it down completely ? The deeper you get into it, more than likely, the more wrong you'll find. This won't be a quickie fix.

 

Buy a new crate engine. Warranty and all= piece of mind.
50 years experience has taught me that new is better. Just saying...


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Not that anyone reads anything anymore,,,, but if they did - haha

they would find

The cam manufacturers say to break the cam in with weak "break in" valve springs then change the valve springs to the heavier ones that match the cam.



Think about this-
You need a belt sander and a catch for the grindings.
Take your cam up to a belt sander and grind off 2 lobes, take 2 lifters and grind off a bunch. Now take all the grindings you caught and dump them into any engine you like.

 

Have you seen what iron ore looks like when it comes out of the ground? It's basically rust. Almost all metal is recycled now. Quality control is likely the reason for bad parts. The metallurgy has to be right as well as the heat treating. If I was building now I would be doing Rockwell hardness testing on the cam and lifters. I've seen a roller bearing with a soft inner race that rolled out like pie crust.