Valve lash keeps getting loose

[miller]

So I'm thinking that the metal that came off the cam lobe, (.120" off the top) may have been suspended in the oil.

Just re-read the entire thread. .120" off the lobe? Did you measure the lobe itself, once the cam was in your hand? I know you've done alot of checking for metal, but...

Keep something in mind. It is possible that metal particles can get trapped in some pocket. There's plenty of places inside a block, for that stuff to get, and break loose later, once oil gets to it.

All I'm saying is be sure! Even flushing is a waste of time, unless the motor is down.

 

[Garys1969RR]

Just re-read the entire thread. .120" off the lobe? Did you measure the lobe itself, once the cam was in your hand? I know you've done alot of checking for metal, but...

Keep something in mind. It is possible that metal particles can get trapped in some pocket. There's plenty of places inside a block, for that stuff to get, and break loose later, once oil gets to it.

All I'm saying is be sure! Even flushing is a waste of time, unless the motor is down.

The lift at valve was .520" before the lobe started to go. After the problem started, I measured it at .380 lift at valve. That's a loss of .180". Since rocker ratio is 1.5, the lobe would have lost .120" off the top. A little over 1/10 of an inch of the lobe gone.

 

[IQ52]

Hey, no problem. Some people lap in their valves. You are just lapping in your entire engine!

 

[khryslerkid]

The lift at valve was .520" before the lobe started to go. After the problem started, I measured it at .380 lift at valve. That's a loss of .180". Since rocker ratio is 1.5, the lobe would have lost .120" off the top. A little over 1/10 of an inch of the lobe gone.

Thats a combination of lobe and lifter.

Have you decided to tear it down yet?

 

[Garys1969RR]

I have the motor partially disassembled at this point. Still undecided as to what to do next. Looking at the lifter valley, the crankshaft, and bottom of piston skirts, I have yet to find any signs of metal shavings or any damage. I suspect the bottom of the oil pan is where I might find some. That's prob what I should do next. Pull the oil pan.

 

[Fran Blacker]

Maybe you should just pull the motor and drop the pan without flipping the motor upside down. then put it on a engine stand and inspect it. If you don't have A/C how long can it take? Put an engine in my Satellite and dumb *** me didn't crank up oil pressure. Started engine and it was dripping out the back. Pulled the engine, one of the gallery plugs was leaking. Tighten it up AND cranked oil pressure no leak. Put motor back in and fired it 8 hrs, by myself. I was younger then 50 years old, don't know your health.

 

[miller]

Since rocker ratio is 1.5, the lobe would have lost .120" off the top. A little over 1/10 of an inch of the lobe gone.

IQ52 well has a point! Way too hard to armchair quarterback on this stuff. What I was seeing is a caved-in tappet surface, and the hammered effect on that lobe (why the lobe edges are rolled over).

If the numbers in your quote are correct, big time questions! But, again going by your photos isn't enough. As far as that cam lobe itself, only one number is needed. The true measurement off that lobe itself, heel to toe...nothing else in the way. Compare it with some of the other exhaust lobes, to get the real number.

If there is loose metal, it has to be in the engine 'somewhere'. Take a look at one of the oil galley diagrams, it will show areas that need to be looked at, one way or the other.
Your the one with parts in hand...only you can decide.

 

[Garys1969RR]

Pulled the pan off, and no metal particles anywhere. Engine looks clean on the inside.

 

[miller]

Admit that is curious. But still curious about the measurement on that cam lobe itself.

When you pulled the lifters, any hang up in the bores? Suppose you already know there's two plugs you can pull from the front of the block, under the timing chain gear, that gives you access to the two oil galleys that feed the lifters.

Just strange your not finding metal...unless, like you've already said, very small particles that came out with the oil. Even so...a magnet would have picked 'em up.

 

[Garys1969RR]

Lifters came out smoothly, no sticking at all. This was just 1 lobe that started to go, and I caught it right away. It's not like several lobes went completely flat. I'll measure the height of the worn cam lobe and compare it to a few other ones.

 

[oldbee]

'Garys' , way back I had a GMC pickup and the cam went south(85?,notorious for cam failures); had a spare GM cam in box,drained oil,installed spare & went another 100,000 before I traded it in.Lucky?maybe,don't know but it lived.Every suggestion you have on here is good; it's up to you I guess.

 

[moper]

When I was 17 I thought it would be cool to install a hydraulic roller in my 340. So I bought a Crane cam I liked, and a set of stock hydraulic lifters for a 318, plus the dogbones and spider. Put it all in. Ran great. For a bit. Then started running "funky". Apparently the holes in the spider are for bolts, that have bosses in roller cam blocks. 340s were never roller cam blocks. So... the lifters tossed the dogbones and started to turn. Did I mention the cam I got was a flat tappet? Anyway... All kinds of iron went into the engine. I put the old cam back in and drove it. My ignorance was already showing I hope...lol. Anyway that thing was full of crap when I did take it apart after I blew the ring lands off it and there was iron embedded everywhere. 305 Chevies ate cams too. Just put in new ones. Here's the thing - My engine would have had issues over time - I blew it up earlier. The Chevies were only done to get out of warranty. So it's up to you. It would bug the **** out of me. It's your car and investment.

 

[oldbee]

Kinda true on all points 'moper'.. Although the pickup was out of warranty..Don't know where those "great" camshafts came from in the 80's for GM. Never saw any tech bulletins about them.

 

[Fran Blacker]

When I was 17 I thought it would be cool to install a hydraulic roller in my 340. So I bought a Crane cam I liked, and a set of stock hydraulic lifters for a 318, plus the dogbones and spider. Put it all in. Ran great. For a bit. Then started running "funky". Apparently the holes in the spider are for bolts, that have bosses in roller cam blocks. 340s were never roller cam blocks. So... the lifters tossed the dogbones and started to turn. Did I mention the cam I got was a flat tappet? Anyway... All kinds of iron went into the engine. I put the old cam back in and drove it. My ignorance was already showing I hope...lol. Anyway that thing was full of crap when I did take it apart after I blew the ring lands off it and there was iron embedded everywhere. 305 Chevies ate cams too. Just put in new ones. Here's the thing - My engine would have had issues over time - I blew it up earlier. The Chevies were only done to get out of warranty. So it's up to you. It would bug the **** out of me. It's your car and investment.

As long as you learn from your mistakes, your going in the right direction. It can get expensive.

 

[miller]

I'll measure the height of the worn cam lobe and compare it to a few other ones.

That's all you can do...look. Investigate, and decide.

If there was metal, my experiance is there would be metal through out the engine. At least signs of it. The real sticking point is the crank, with all the oiling ports inside it. That's why I mentioned #4 main cap, to look at the bearing half.

 

[moper]

We learn every day - unless we're close minded...lol
Problem I see is - no metal in the filter. No metal found anywhere. And missing metal from the cam. If it cam off the cam or lifter - it's in there. If you haven't found it - it's still there. If it was mine, or you were a customer of mine, I'd be doing just that: tearing it all down to start verifiably clean. Ultimately it's Gary's investment of time and gold.

 

[miller]

To a point, I'll agree, moper. It's about investigation...and deciding. In motors, there's really no telling what you find, until you dig deep enough.
Still curious on that lobe measurement! Errr...did I say I'm a pain!

 

[Garys1969RR]

UPDATE: Got the roller cam in, drove it today and it's running great! Breaks the tires loose in second, when the (six pack) end carbs open. Just like before. Oil leak on dr side valve cover. Motor oil is still clean, I changed it and the filter after the one cam lobe started to go. I have oil and filter on hand, so I can change it for the second time tomorrow. No signs of any oil contamination after driving it. Motor is quiet and responsive. Oil is still a clear amber color, just like new. Compression was checked after the new cam installation, and it had 210 lbs on #1 and #7. It was 195 with the old cam. Alternator is over charging, so I ordered a new voltage regulator.