warning signs of cam failure

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340 8BBL

340 8BBL

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ive heard alot of talk about cams going flat recently.having done a swap a few weeks ago i was interested in what the warning signs might be.also what kind of time frame does this happen in?
 
A very loose rocker or rockers.
When the lifter looses all the pre -load due to the lobe on the cam going away it will start to make a lot of noise that won't going away cold or hot.
It wont run right and you will have metal in the oil.
 
Once the cam starts to "go flat" the damage progresses quite quickly. Also, typically it is the lifter face which fails first wiping out the cam lobe.
 
C130 Chief said:
Once the cam starts to "go flat" the damage progresses quite quickly. Also, typically it is the lifter face which fails first wiping out the cam lobe.
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how much run time before your in the clear so to speak,i know the first half hour is critical.....ive probably got 15-20 hours run/drive time on it.
 
My advice is if you think it might have an issue, pull the intake and look. It's an afternoon and $20 for a gasket. Once the oil wedge between the lifter face and lobe are compromised the damage is immediate. It occurs on a sliding scale...lol. The lifter and lobe lose intergrity in under a second, then the parts just start grinding each other for as long as you let them. So really there is no set amount of time. It could even be damaged by trying to pre-oil by using the starter and turning the engine over too much. Then when you fire it, the parts already don't have the oil wedge there and they go bad during break in.
 
The ones I've seen that go bad have done it real quick. 20 miles or less. As stated earlier you have lifter clacking due to excess lash.
 
It will sound like you have a miss or fouled plug, loose rockers, clicking rockers, etc. Mine went flat in less than 20 miles after break in.
 
moper said:
My advice is if you think it might have an issue, pull the intake and look. It's an afternoon and $20 for a gasket.
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If he used Fel-Pro print-o-seal he could just reuse the gasket. I high tack it to each head and use no sealer on the intake side. I reused those gaskets time after time for years.

Edit to add that the gasket stays on each head, the hi tack and heat glues the gasket to each head. With the steel core insert the gasket doesn't tear, looks as good as new just about. Only thing I touch is the rtv on the ends of the block.

Bbm guys have it made, they need not to even drain the rad. For them an intake swap can be a under a 1 hour job, lol
 
It was the lifters.
They are anti pump up lifters from crane and are a little noisy.
I was wondering if he should be running adjustable rockers with them, so he called crane and asked.
He said that the fast bleed lifters needed adjustable rockers, but not the regular anti pump lifters that crane sells.
 
T67POWER said:
It was the lifters.
They are anti pump up lifters from crane and are a little noisy.
I was wondering if he should be running adjustable rockers with them, so he called crane and asked.
He said that the fast bleed lifters needed adjustable rockers, but not the regular anti pump lifters that crane sells.
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He's wrong. ALL anti pump up lifters have to have an adjustable valvetrain because they require different lifter preloads.....some even recommend running up to .002" valve lash. They MUST be adjusted much looser than a regular hydraulic lifter or they will fail.
 
"fast bleed" are anti pump up lifters and in Crane those are the 99278-16s. Standard lifters are... well... basically stock. Those in Crane are 99378-16s. If you're reading the catalog (and my impression is the "tech" guy was...) the write up is the same for both lifters, but only one set is really the anti pump up. As was said, anti pump ups need much less preload. Usually around .010. Standard lifters can have as much as .060 preload and as little as .020.
 
I don't know exactly what lifters he bought from crane, but i guess he talked to them about it, and was told they tend to be noisy and don't need the adjustable valve gear.
He told me he didn't buy the fast bleed lifters.
You need adjustable rockers for those according to crane.
I wonder what part number they where????
May be just a hi performance hydraulic lifter with better valving, and he's talking about how they are resistant to pumping up.
 
the lifters are pn 99278-16.it runs and idles perfectly.ive got 200+ miles on it now since the swap.i drove it to work a few times which is an 86 mile round trip.the valve train noise T67 mentioned is not what id consider excessive by any means.its very very slight.this is the 4th schneider cam ive run and every one had a little noise ,not like a loose rocker or collapsed lifter. all the stories of failure ive heard lately made me have some concern.
 
Glad every things ok 66.8)
How this cam run and what are the specs????
 
T67POWER said:
Glad every things ok 66.8)
How this cam run and what are the specs????
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nothing special,284* 234@50 470 lift 112 lsa. +2 .very streetable.runs real strong from about 2000 to 6000.decent idle as well,14" of vac.i swapped from a 280/290 on a 108 lsa.it did lose some power,but is much better"driver".not so all or nothing lol.
 
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