Thread: The more I learn, the less I know...

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A few days ago, i posted about "dropped a valve" in my 350.
Pulled the valve covers and found all valves in place
.... "noise" problem was a broken rod on the #4 exh. Nearly broke in half, so I'm wondering what I should be looking for as a cause. Other things to be concerned about?
I have checked the distributor and timing marks, etc... all ok there.
Checked lifter travel (removed another rod and put it in #4, turned crank by hand and measured distance open and closed for comparison) and seems very close to other cylinders.
Replaced the rod and have done initial rocker adjustments.

There are a few reasons why a push rod will come out of it's socket in the rocker arm and or lifter.

1. Rocker arm nut came lose.
2. Rocker arm stud pulling out of head, or unscrewing.
3. Rocker arm broken in the area where the ball sits.
4. Valve sticking open due to tight valve guide.
5. Weak valve spring.

I'm sure there are a few more that I can't think of right now.

6. Bad metallurgy.

Is this a new or rebuilt engine? If you have a big cam in it, coil bind (valve spring bottoming out) will break pushrods.

7. wrong combination of rocker arms and pushrod holes in the heads (pushrod rubbing)
8. pushrod column failure from a previous event (dent in pushrod)
9. really bad karma

from my own personal experience:
10. missed shifts
11. losing traction in second gear and zinging the motor a tad
12. if it's got t__s or wheels, eventually it's gonna give you trouble.

Thanks to all of you...
HRP: it's rebuilt, but the cam is not radical (.434 int / .444 exh).

Pro60: Good list... thanks...

Tech: mebbe, but...

robot: interesting point about the rods / holes. Both heads are the same casting# 14102193. Driver side bank has round holes for the rods / pass side has elongated holes. Rockers on d/side are correct part, with "stops" on the edges to keep the rod in the vacinity of the valve. p/side had different rockers... smooth and nothing to guide the rods. I was able to move a rocker almost completely off the rod by hand. Could this be the "smoking gun"?
Still can't rule out karma...

Dave: #12 is rat on da money :-)

Tonight, I changed all rods and rocker assemblies. hand cranked it around 'n around to look for potential problems / binding / etc.
All looks ok, but i'm a little nervous about actually starting it. Thinking about using it for a planter, or really big yard art... sigh... shoot, I guess i'll polish up the ol' cajones and crank her up

So, how did it come out???? Can't leave us all just hanging here, how does it run??????

Are you using guide plates with unhardend push rods

383: nope.. stock rods, rockers, pivots & nuts for '87 & up 350.

More issues & a little history of how I got to this point.
# 1 - a repair shop guy ( I know... don't ask...long story) said that the groove for the valve retainer was "boogered up at the top of the groove and he didn't know why. He suspected a bad lifter, so he replaced it. This was on the #3 exh. (for some reason, he also replaced #5 exh.) then he adjusted valves with engine running. He said "adjusted ticking noise out of it, but it came right back. Unable to keep 'ticking noise' out of engine". He then warned me that I would drop a valve if i didn't rebuild the heads.
At that point, I picked up the truck from the shop and drove it on a short trip... when the rod broke... then towed it home and tore it down...
Now, if y'all have the patience to re-read this whole thing (thread) to see if any of it makes sense, maybe someone can tell me if you think I might really drop a valve.
Gawd... I'm such a noooooooob... this is my first engine rebuild & i was really proud of it... don't want to do further damage.

I really appreciate all your thoughts, so far...

Before you go any further. Take a straight edge and run it scross the tops of all the rocker studs. See if any of them are higher than the rest. If they are all the same, you have a lifter that has gone bad and is leaking down. If one of the studs is in fact taller than the rest, chances are that is the one that is giving you the trouble.

Hope y'all had a safe holiday... not ignoring your posts, just got too busy to get on the 'puter.

First: pro60chevy... checked as you suggested. Ordered new set of comp cams' lifters that they recommend for my cam. Should be here by Thursday.

Second: Denny 'meboy from Illinois... I was surprised to find that one head had the correct rockers (with the rails) and the other did not. I could twist the rockers off the valves with my hand. Perhaps a clue there, eh? I have new rockers, push rods, pivots and nuts for both heads.

Removed the heads and took 'em to "Lee" to have them inspected. He found all the valve guides worn. He'll replace the guides, do a valve job and make sure all is ok.

Anything I need to be sure is done to the heads before I get 'em back? I don't want to leave anything important out, but I'm not made of $$$ :-)

btw... these are 193 heads... should i just dump 'em and go for something else? The whole head thing has me going in circles...

well good info guys. please don't bash me here but... worn valve guides and being able to move rockers off rods tells me push rod lenght should be checked. these dont sound like stock heads all though i could be wrong.. push rod lenght is extremely important for proper geometry of valve to rocker arm.