What Keeps Taking Out My Camshaft?

[mrein3]

I have owned my truck for a little better than 10 years. When I bought it there was a 350cu. in. engine in it of questionable origin.

Not long after I bought it I had to do a valve job. Since I had the engine apart I put a new cam in.

About a year ago I was moving stuff to a storage locker because I was selling my house. I made a lot of short trips and noticed my truck didn't have the snuss it used to. Then it start spitting back up through the carb. I pulled the valve covers and noticed some of the rockers weren't moving as far as the others. I ordered another camshaft and when I pulled the one that was in there two of the lobes were pretty flat.

So fast forward to today. I made a 15 mile run to buy some stuff for the garden. On the way down I noticed a familar lack of performance. On the way back it was spitting through the carb again.

At stop signs my oil pressure gauge goes to nothing. Am I not getting enough oil up there? Is that what is taking out my cams all the time?

I want to build up a 383 but not quite this quick. If a cam only lasted a year is it now time?

Maybe I should be happy. I've been looking for a legitimate excuse to put a better engine in there.

[FRENCHBLUE72]

Have you replaced your lifter's each time you swapped cam's???

[mrein3]

Yes. Both times a new cam and lifter set.

[cduster]

Same lobes every time? Are all the pushrods oiling? Maybe you have a plugged oil passage or a cam bearing not installed properly that is restricting the oil flow.

Dan

[cableguy0]

what kind of cams are you using just stock cams or a performance cam? if your using a performance cam are you doing the proper break in

[69 Short Fleet]

It sounds like lack of oil, might be a little off topic but I went through 3 sets of cams (on a Z1 Kawasaki engine) and the PO had everything bassackwards. First, he had the oil pump "Hotrodded" and it was starving #2 cyl. next he had the head gasket blocking off one of the oil galleys, ect ect ect. The camlobes were all damaged on the same cyl. each time, I'd probably pull the engine and completely dissasemble everything and that way you know whats up or like ya say change the whole motor. Best of luck, Doug

[68C15]

'm with cduster.
you now have an excuse to do the 383. tell wife it will save money in longrun.

[Randy70C-10]

Who is the cam from? I had some bad luck with a couple cams from "CompCams" as well as some of my buddies. I wore out two of them in a year's time.

[cdowns]

if it's high-milage engine you could need new cam bearings,if so go for a complete rebuild

[Randy70C-10]

To add to what he said, you may need a line-bore as well.

[mrein3]

Originally Posted by Randy70C-10

Who is the cam from? I had some bad luck with a couple cams from "CompCams" as well as some of my buddies. I wore out two of them in a year's time.

Funny you should say that. BOTH were CompCams. They weren't a stock grind but they weren't too wild either. I wrote the numbers on the grind down somewhere. The last time the farthest back (number 8?) was flat and the 3rd from the back was flat too. I just parked it yesterday and got on with everything else I had to do.

What scares me about putting in a different engine at this time is that I have a 700r4 that I want to have rebuilt and stick in there. If I got the engine out I may as well do the tranny at the same time. That means driveshaft work. As long as the engine is out I may as well also paint up the frame.

I could get by with putting my current heads on a short block and spending only around $500 or $600. If I start down the 383 and 700r4 slippery slope I'll be tripling that price. Gulp. Sell that to the wife.

Either way I'm putting a two piece timing chain cover on it so the next time I wipe out a cam I won't create the front oil pan leaks that are nearly impossible for me to avoid. You guys have any suggestions on two piece timing chain covers? Is my 1406 Edlebrock carb that is still in the box big enough to handle a 383? Is a 383 worth the extra money? My rebuilder friend has a 400 crank waiting for a project like mine to come along. He said the price difference between rebuilding the 350 I have already on the shop floor and making it a 383 is small. He suggested I do the 383 short block and put my heads on there. If I want to change heads at a later date that would be easy.

Plan B is the cheapest. My 72 Chevelle has a VERY fresh 350 in it. I don't drive the car much any more. Putting that in the truck is a weekend project and nearly free. Then at my leisure I could build up a killer 383 for the car and start driving it again.

[Randy70C-10]

My cams weren't wild either, they were for a blower. (a little bigger than stock). I've heard from a few guys on here that they had them go bad too. Never really hear much about any other cams going flat, you might want to try a Crane or Lunati.

[bigjimzlll]

Just a point to think about....When a lobe or two goes flat...the cam guts(fine metallic,bearing destroying,oil passage clogging) go though the entire oiling system. I have been lucky once or twice by just swapping cam and lifters. With out tearing the complete engine apart and cleaning everything. I have also seen the carnage the cam guts can cause.

Usually a cam will go flat because of inproper break in.

[72C203503ONTHETREE]

I have heard a lot about Crane cams going flat also, so not every cam maker is perfect. One guy I knew went through two Crane cams in a Chevy big block but had the best luck with a Comp Cams, lol. The 1406 carb is a 600cfm isnt it? Thats too small for a 383, may be a bit small for a well built 350 to. I would use the 1407 750 cfm on the 383 if its going to be run at mid to upper rpms. Edelbrock and many others sell two piece front covers, check in Summit Racing. I just replaced the cam in my 72, I just filled the groove in the cover with Ultra Blue RTV and stuck it on, no leaks.

[Cat Fuzz]

If I remember right, the cam is oiled by the crank slinging oil up out of the pan and onto the cam lobes. This is why you run the engine up to 2000 rpm's or so to break in the cam, so its gets plenty of oil. Cam bearings don't normally wear out. They only get replaced because hot tanking destroys them.

Did you break in the cam?

[mrein3]

Originally Posted by Cat Fuzz

Did you break in the cam?

Both times I followed the cam manufacturer's break-in spec to the letter.
Plus I attempt to not let it idle. I shut it off rather than let it sit and idle.

I'm guessing that the engine, which is of an unknown pedigree, is just plain tired. The bottom end of it is AT LEAST 15 years old. I've had it 10 years and the guy I bought it from had it about 5 years before that and he never did anything to it.

I think it is related to the fact that when at a stop sign the oil pressure gauge bottoms out after the engine is warm.

[CHEVYE]

my buddy had the same thing out of 2 comp cams in a row.

[72C203503ONTHETREE]

If you have low or no oil pressure at idle your bearings may be shot and need to replaced. If the clearance is too great the oil at idle isnt forced out enough to get to the cam lobes. My truck still has decent but not great oil pressure and it ate its cam.

[mrein3]

I think I know what my father's day present is going to be.

My rebuilder has a 400 crank just waiting for a project like this. He called his warehouse and had them hold a set of 383 pistons (he said they are different than the stock 350 pistons - but not much more money). The 350 block I'm going to use is a virgin block out of a 1971 Monte I parted out a few years ago that used to be my winter beater.

When the bills start to get totaled up I'll decide then on the 700-R4 I have sitting on the shop floor next to the Monte's 350. It needs the Advanced Adapter's 4wd output shaft and a rebuild.

[Baradium]

Originally Posted by mrein3

Both times I followed the cam manufacturer's break-in spec to the letter.
Plus I attempt to not let it idle. I shut it off rather than let it sit and idle.

I'm guessing that the engine, which is of an unknown pedigree, is just plain tired. The bottom end of it is AT LEAST 15 years old. I've had it 10 years and the guy I bought it from had it about 5 years before that and he never did anything to it.

I think it is related to the fact that when at a stop sign the oil pressure gauge bottoms out after the engine is warm.

Not ever letting the engine idle is bad for it in general...

I try to let an engine warm up as much as possible at idle before going anywhere with it. I also try to let it sit and idle for a few minutes for a proper cool down before shutdown if it's been loaded down.

The more you let the engine idle before driving it to allow the oil to circulate and the engine to warm up the longer it'll last for you.

It's also better to let an engine idle if you are going to be using it again soon. It's easier on it to let it idle and then go back to using it than to shut it down and then restart it. The most wear on all components happens at startup, once an engine is up and running it keeps itself oiled, but after shut down the oil drains back and the startup is dry for a short period.

15 years old is nothing, and age alone doesn't determine condition. My '70 still has it's original engine in it. And my oil pressure is fine at hot idle. That says cam bearings to me if you don't have any pressure at hot idle (although it could be other bearings too). And some engines do eat cam bearings. I wouldn't ever want to change a cam without changing the bearings too (yeah it's more work, but it's worth it).

What oil do you run? The owner's manual for my '70 says to run 10W-40 in most conditions.

[mrein3]

Originally Posted by Baradium

Not ever letting the engine idle is bad for it in general...

I try to let an engine warm up as much as possible at idle before going anywhere with it. I also try to let it sit and idle for a few minutes for a proper cool down before shutdown if it's been loaded down.

The more you let the engine idle before driving it to allow the oil to circulate and the engine to warm up the longer it'll last for you.

It's also better to let an engine idle if you are going to be using it again soon. It's easier on it to let it idle and then go back to using it than to shut it down and then restart it. The most wear on all components happens at startup, once an engine is up and running it keeps itself oiled, but after shut down the oil drains back and the startup is dry for a short period.

15 years old is nothing, and age alone doesn't determine condition. My '70 still has it's original engine in it. And my oil pressure is fine at hot idle. That says cam bearings to me if you don't have any pressure at hot idle (although it could be other bearings too). And some engines do eat cam bearings. I wouldn't ever want to change a cam without changing the bearings too (yeah it's more work, but it's worth it).

What oil do you run? The owner's manual for my '70 says to run 10W-40 in most conditions.

I disagree about leaving your engine idling. Too low of an idle is real hard on your camshaft.
15 years old IS nothing but that is the only history I know about the engine. I've had it 10 years and my friend had it the 5 years before that. Somebody else put the engine in. When I took the heads off to do a valve job they weren't from a mid 80s truck like the stamping on the front of the engine indicates. So who know what the person who did this was thinking.
I'll be darned If I'm going to take this engine out of the truck, replace the cam bearings, then put the same knocky, smokey, cam eating engine back in there when for a couple hundred more bucks I can have a fresh 383. The engine is tired and I'm tired of throwing money and time at it.
I run Mobil 10W-30 year round and change it every 2000-3000 miles "whether it needs or not". The 10W-40 that your 1970 owner's manual is talking about is far different than the stuff on the shelf today at Wal*Mart. The 350 I put in my '72 Chevelle in 1989 has had nothing but 10W-30 in it since the day I dumped the break-in oil. The 307 in my '71 Chevelle has had nothing but 10W-30 in it since I bought it in 1987 or so. I believe thicker oil would only have prolonged the inevitable on this soon to be boat anchor.

[DeepPurple]

You ARE using straight 30 or some such right? Not 10w-30 or some such?
I've seen cams not do well after people have used variable weight oils.

And fwiw, the only cams I've never seen failure in is Isky cams, but they're pretty much racing only.

As far as the 383, as long as it's built right, it's an excellent upgrade. And as long as you don't mind re-jetting the carb, a 1406 will run fine on the engine unless you're racing it. And if you're racing it then any Carter/Edelbrock carb is probably not the best choice.

[Ratpowerd67]

yah, comps cams suck. ive been trough several on big blocks mostly. have very good luck with crane.....rat

[Stroker]

I've got to agree with mrein3 about low idle speeds and camshafts. For a flat tappet cam most of the damage is done to the nose of the lobe at idle speeds. I personally don't set idle speed below 1,000 rpm if higher than stock valve spring pressures are used, even if the engine will idle at a lower rpm. I also think it's a wise move to let engine and oil warm up to operating temp before putting the hammer down, too.

It's hard to say what's taking out the cams but the low oil pressure isn't a good sign for the engine in general. The real enemy of the cam is friction and it could be a number of things causing it to be excessive. I think most of them have already been brought up. I didn't notice how long on average the cams where lasting. If there going flat after only a few hours of operation I would look for a valve train binding problems. If they last for several thousand miles and the lobe failures are random then it would be more likely a problem relating to lubrication, lifter to cam geometery or high spring pressures.

I think the Fathers Day option is the best invesment at this point. Sometimes it just doesn't make sense to keep throwing good money after bad. I think you'll really like the added torque.

[mrein3]

I just found my notes on the mileage of the cams.
I put my first cam in at 46115.1. At that time I also put new heads on. I didn't right down the date but it was approximately 1998.
I did the 2nd one on 5/24/03 with 62066.3.
As it sits I have 64071.0 on the odometer.
So 15,951.2 for the first cam. 2004.7 for the 2nd one.