Cam a cam wear out?

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DQ81

'73 Dart
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Lookin' at a car, owner says his mechanic say the Cam is worn out because her ran with too little oil. Claims there is no other damage.

Haven't actually been to see it yet so don't know how it runs. Owner says it runs fine but when you floor it, it chokes.

Is this at all plausible?

I must admit this is a chebby I'm lookin' at.

Thanks.
 
It is possible but I would look at all other possibilities why it is "choking" (i.e. fuel delivery, vacuum and/or timing issues, etc.) before digging into the motor for a cam change.
 
GTXperience said:
It is possible but I would look at all other possibilities why it is "choking" (i.e. fuel delivery, vacuum and/or timing issues, etc.) before digging into the motor for a cam change.
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Good call, it's just that I spoke to the owner and he claims his mechanic diagnosed it as a 'worn cam due to lack of oil'. Symptoms being chocking at fuller throttle and a tapping sound at fuller throttle.

Maybe BS his mechanic is selling him to get some cash off him I don't know.

Suppose the timing chain could have jumped etc.

Any symptomps that are worn cam specifc that I don't know about?
 
Bought a 69 383 Charger with a wore out cam and messed up timing chain Replaced all and valve job, The car ran its $sss off after that.
 
Mad Dart said:
Bought a 69 383 Charger with a wore out cam and messed up timing chain Replaced all and valve job, The car ran its $sss off after that.
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Nice!

I'm just trying to rule out any other major work on this thing. I can pick it up for a grand and it's got all the goodies on it I want for a beater...

it's a gm though.. and valves jobs on those things are a b$tch...but to beat the snot out of could be fun :)
 
I have had several engines that had flat cams over the years and you can get by with just changing the cam & lifters. However, you really need to know why the cam went flat. If it was for lack of oil, there is going to be more wrong with the engine than just a cam & lifter set. The cam gets oil from oil passages in the brg journal, the lifter bore and the run off from the heads. The oil passages that supply the cam with oil also supply other parts of the engine and if the cam was starved of oil, so were the other parts that are down stream from the cam, so there will be other damage.

I have also seen cams go flat simply because it wasn't broke in correctly or it was a used cam and they didn't match the lifters up with the lobe it was originally matched to.
 
Blownfish said:
I have had several engines that had flat cams over the years and you can get by with just changing the cam & lifters. However, you really need to know why the cam went flat. If it was for lack of oil, there is going to be more wrong with the engine than just a cam & lifter set. The cam gets oil from oil passages in the brg journal, the lifter bore and the run off from the heads. The oil passages that supply the cam with oil also supply other parts of the engine and if the cam was starved of oil, so were the other parts that are down stream from the cam, so there will be other damage.

I have also seen cams go flat simply because it wasn't broke in correctly or it was a used cam and they didn't match the lifters up with the lobe it was originally matched to.
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Went and had a look today at the Buick.

It was a pretty decent ratrod, not rusty at all. And as a bonus has a pretty high stall converter fresh in there. I took it easy as I didn't want to damage anything further.

Motor was a beast but it runs like it has a massive cam at idle(rythmic lope) and shakes slightly (not terribly) but otherwise sounds super healthy, all cylinders fire etc.

It's only when you apply the throttle moderately and increasingly that you get rythmic and light backfires through the carb, very high ticks, slightly visible with the aircleaner off.

When driving same thing...but it runs very well otherwise and doesn't sound bad either, no other ticks, knocks or anything.

Ideas?

David
 
is it possible this thing is all carboned up and just needs a good old fashioned thumping.along with some sea foam?sounds to me the valves are hanging open far enough for this to happen.
 
Id put my money on the exhaust lobe on the cam is flat. This causes the cylinder to actually push the exhaust fumes out the intake valve since it has no where to go. Some other things to consider (if its chevy powered especially) are Broken exhaust rocker, Rocker stud pulled out of the head (which is really common on chevys witha big cam and press in rocker studs), Bent pushrod, faulty/stuck hydraulic lifter, or miss adjusted valve (lifter preload). Chevys are notorious for these different condition and I highly doubt that low oil will cause any of these conditions without a rod knock to go with it. You can find which cylinder it is by spraying water on the header near where the exhaust flange/head flange with the headers warming up after initial start up. You can also disconnect the plug wires one at a time and the popping will get less sharp when you find the cylinder. If the car is at the mechanic still then just pull the covers and take a look it will be obvious when turning the motor over with the starter. Good luck, if its cheap and has a lot of goodies it may be worth it.
 
My 86 Daytona Turbo Z had about a tenth of an inch worn off of all of the lobes and ran just fine.

The only problem it had was a blown head gasket at 250K miles.

I religiously changed the oil every 10K miles and only used Mobile 1 synthetic.
 
Is it a 305? They were known to wear out cams... If it's popping, there's valve sealing issues somewhere. Might only be one. But I'd assume it needs a valve job and price accordingly.
 
moper said:
Is it a 305? They were known to wear out cams... If it's popping, there's valve sealing issues somewhere. Might only be one. But I'd assume it needs a valve job and price accordingly.
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No it's a 350 but that's the same block in essence...

I'm goin' by a buddy's today who's all Chubby, I mean Chevy, I mean crap, I mean, you know...lol

I'll get him to price me on the job, I'll beat the snot out of it but I don't like working on those heads/valves too fidgety...
 
You say it only does it when you are getting on it a bit and that it runs fine otherwise. You may want to pull the balancer off and the timing cover and check the crank to cam timing. It sounds like it may be off. That will cause the symptoms you are stating and it is a pretty easy check.

Jack
 
Take into account the recent changes in oil regarding a reduction in zinc. Older cars run on current EPA approved oil have a tendency to wear down on cams. Our flat tappet engines need an additive, or non EPA rated oil for longevity.
 
GM 305 is the cam eatingest engine I've ever seen. They showed plenty of oil pressure but didn't have enough wash/volume/flow whatever you wish to call it. During 4 years as a used car mechanic at a dealership I lost count of how many of those cams I replaced, atleast 15.
 
Red, I agree with you on the 305, and a lot of the 350's also. I've seen the lifters so hollowed out on the face that you could use them for wine goblets. Made quite a few bucks back in the day changing out those rounded cams and hollowed out lifters.
 
Yup the trouble you are describing with the pop through the intake is the very common Chevy bad cam and if you keep thrashing it as it is running you will break the intake pushrod on that cylinder. Been there seen it many times. Throw a cam and lifters in and check for bent pushrod and she will go many more miles.
 
moper said:
Yeah, 305s are "special" that way...lol.
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Thanks guys.

Just for the record, I have stated it's a 350. NOT a 305, but in this case potato/potaatoo.

It's not being driven momentarily. but would it be allright to run it one 40 mile trip to the mechanic or better off towing it?

cheers, David
 
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