What caused this

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highflyer

highflyer

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I went to replace the intake gaskets today and found this .I was really not expecting something like this...less than 500 miles new cam and lifters new or rebuilt everything..i did not OVER rev the motor and don't think the kid did either..but not positive BOUT THE SON..what could have caused it I found two bent pushrods...im the only one that drove it for the last month since my sons been back at school...I found two bent rods..now the question is what damage am I looking at...cam lobe..valve..from just looking ,I don't see any damage at the lifter og valve..ill be in it a little better tho tomorrow..what do you all think...tx...j
 

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Do you have the recommended valve springs on it? If their too light it could have floated a couple valves and they smacked the pistons. Pull the lifters out 1 by 1 so you don't mix them up and see what the bottoms look like. I assume you (or whoever built the engine) checked lifter preload to make sure the pushrods are the right length?

LOL on the kid... I was terrible about running the old mans car hard whenever I got it... A rev limiter sure helps with those problems.
 
I don't see any scratch marks in the pic, but make sure you have clearance where they pass thru the head opening? I learned to use moly pushrods only after I found a slight bend in some during inspection. The only time I ever bent some like that was when I had a spring failure. Make sure you inspect them also. Was the engine making noise?
 
Some general ramblin'............

Seems to me that on the www we seem to see a LOT of bent pushrods.

(By the way, I don't understand how anyone can run an engine for long and not notice...........)

Take a good hard look at the engine build. What did you use for parts, rockers, pushrods, lifters, and do all these provide the proper geometry?

and are you confident that the valve to piston clearance has been properly checked?

Has the engine been over-revved? You have a rev limiter? In this day and age there is no excuse NOT to have one. "It only takes once"

Now contrast that with my old 340, after it was gone through and in my old Landcruiser. That thing had factory 273 rockers, a mild solid cam, and pretty much all factory equiv. parts, and no head nor deck milling.

I ran that thing HARD you'd get stuck in a mud hole or in the snow, that thing might see 5--7K for 1/2 minute getting the tires cleaned up and out of the hole, all told. This happened especially chompin' through deep snow.

NOT ONCE did I bend or break a PR or suck a valve. And those same rockers/ pus rods are on the 318 right now, although it just came out of the car for paint.

As hinted above, I would seriously consider pulling the heads for inspection, or at the very least run a leakdown test
 
OUCH !!!! I'm with Dart273.. If 340's are put together right they are just about indestructable.
 
could be a guide that was to tight and stuck causing the push rod to bend like that.

Put a new push rod in and see how the compression test compares to the rest of the cyl.

You are probably going to be pulling and head to replace a valve. and maybe a valve guide.
 
Gator said:
OUCH !!!! I'm with Dart273.. If 340's are put together right they are just about indestructable.
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Not true but sounds good. lol either it was over reved or the vale or lifter hung up. If the valve hit the piston its bent and you would know it. Put a new one in and do a cylinder leakage test on the cyl's in question.Then you will know what you have as far as damage. There is no sence tearing it down till you do this.As it could be just not heat treated properly. Happens a-lot on new motors . and all sourced parts.
 
67Dart273 said:
Some general ramblin'............

Has the engine been over-revved? You have a rev limiter? In this day and age there is no excuse NOT to have one. "It only takes once"

Now contrast that with my old 340, after it was gone through and in my old Landcruiser. That thing had factory 273 rockers, a mild solid cam, and pretty much all factory equiv. parts, and no head nor deck milling.

I ran that thing HARD you'd get stuck in a mud hole or in the snow, that thing might see 5--7K for 1/2 minute getting the tires cleaned up and out of the hole, all told. This happened especially chompin' through deep snow.

The 340 I had in my 78 cj-7 seen more high rpm, shove the petal thru the floor clearing the tires to come out of the mud action than most people would dare to do on a street car.
It was really light, (single wall fiberglass body) street legal.
The motor would not break, but it would trash a rear end once in a while.

My guess on the bent push rod the valve springs floated and the piston now has nice smiley faces from the valve hitting.
Click to expand...
 
Was the bent part on the top or bottom? was the push rod still in the rocker?
 
If you can get your hands on a flexible bore scope you could pull the plug and take a look at the piston for signs of it hitting the valve.
 
I think most of these have been listed already but these are things to check for.

piston to valve clearance.

Adequate valve springs open pressure.

Unusual rocker wear/damage (on the valve side)

Unusual guide wear/damage

I'm sure you already know this but when you find the problem and rectify it, replace all the pushrods not just the damaged ones.
 
DFX 340 Duster said:
If you can get your hands on a flexible bore scope you could pull the plug and take a look at the piston for signs of it hitting the valve.
Click to expand...

true, but if the engine is already apart far enough visually inspect the lifters and cam lobes, it's really not much extra work to pull the heads and check them properly with your own eyes.

Maybe i'm paranoid, but I don't trust a LCD screen to tell me if my motor is damaged or not.

But then not everybody seems to have the bad luck that I do lol!
 
Has anybody mentioned coil bind on the valve springs - It can happen, and would bend the pushrod on the first start so you would never notice the engine started running different.

You have to check everything when you start mixing different parts.
 
Have you rolled all of the pushrods across a flat surface to see how many are bent? There should not be any "wobble" or bend at all.
 
That has happened on the engine stand before. Everything together then second guessing and going back to turning crank with timing chain removed. The big pull bar on the balancer bolt would make one strong enough to wad up a couple of push rods.
 
I have seen this so many times it makes my head spin and im nearly every case it ends up being valve spring coil bind
 
Well...here it is and thanks all for the ideas and inspiration...I myself and no one else did this to my self..i threw some crap gas in to burn it up..problem is, it had a additive in it that CLOGGED up the intake valves ,when intake opened it stuck open long enuf to lose contact with pushrod,pushrod fell out and landed under rocker arm ,next time bent pushrod,I pulled the heads and found no contact with the valve and piston.. and this is what I deduced.after pulling both heads.the motor is ready to take out and now im gonna add another cam and lifters oil pump and timing chain and gears..one PR was bent 45 or so degrees an inch or so up from the bottom and the other was bent straight on like a 's'..this is the one that really bothers me takes much more pressure to do an s bend than a 45 at one end..my concern now is cam bearings..i wont know till my son and I pull it sunday..the heads ill have to take out all the valves clean them and check the valve guides and do any repairs necessary..i don't think they are hurt but don't know yet..right now I need to come up with a VG compressor so I can take out the keepers..iv got the
" from the top screw type ,but I cant get enuf room to remove them with this type..also found the intake man wasn't quite sealing on one side..i knew I had a slight leak and actually knew where it was..its the problem discussed on FABO about the casting not lining up with the ports on the head.performer.so ill have to center mark every port and check it when I put it back on..side to side compression was good on the old gasket..brand new pistons top were severly coated along with the intake valves and a coating on the cyl walls down 3/8 ..i can move very slightly all the pistons from side to side so I don't think the upper rings are clogged and can only see em move if it has a little oil squirted around piston..good thing if there is any,is it happened in the garage when I was getting ready to pull the manifold to put in new gaskets..it was idling and I had just started it..i heard it bark thru and shut it off...well that's it ..lesson learned..now ill have to clean the tank and lines pump carb new filter.because of one STUPID .SS..ANY AND ALL CRITICISM AND IDEAS ETC WELCOME..J
 
pics of my mess..the clean one [piston]I cleaned and the rest are well you know...this motor had less than 300 miles on it..ran great till I botched it..except a small vac leak ,,but when the motor got warm the vac leak almost disappeared.you can see around the front port where there is no witness mark where the man was leaking.j
 

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I'm not a fan of new Edelbrock quality control.

Before you put that intake back on and attempt to center it, do some further measuring.

The new manifolds have had reported core shift issues. Some people on this forum have been sent 3 manifolds or more and returned them, because they don't measure properly, even on one side, against a gasket.

Measure the distance from the #3 to #5 runners and check to make sure it's the same measurement from #4 to #6 on the other side. The problem people have been showing here is that runner pairs are spaced unequal.

You can also check the short spacing, between each runner set, but that is easier to see with the eye than the longer space. [][]<here>[][]

If the manifold runner spacing on each side checks out, go ahead and center it on your engine. It may require you to oval your intake mount holes on the manifold to do correctly, after you've removed the index pegs from the block. Don't forget to RTV the bolts and put a smidge under the right/ pass. side front corner, where it overhangs, by the timing cover and head. That is a common oil leak spot from lousy design/ gasket coverage.


Also, what kind of additive was used in your engine, just so I know never to use it?
 
Looks like it was sucking oil from the look of the valve stem. I would say more than likely from the intake not sealing.
 
I'm won't pretend to know how the push rod got bent but I do know one thing:

When I was 16 years old I used to drive my Dad's 55 Chevy. I would deliberately look for some one to race. I would get going about 15/20 MPH then slam it down into low (column shift, auto, low is all the way down) and hit the gas. But one time I got to drive the other car it was a 57 ford station wagon automatic. I hadn't driven it much but this time I decided to race it for the first time. So I found a willing racer got going 15/20 MPH and slammed it into low (all the way down on the column shift). Me not knowing cars very well at that age didn't realize that shifting all the way down on that car ('57 Ford) is actually REVERSE!!! So the car abruptly came to a screeching halt. I had to crank on it for about 15 minutes to get it to start up. Drove it home and said nothing to my Dad. A few days later my Dad complained about the Ford not running right so he asked me to help him fix it. Long story short...my Dad removed one of the valve covers and found two broken rocker arms. He had no idea how they got that way and I wasn't about to say a word.:-?

I'm not saying that's what happened here but it's a true story. I think I got the cars and years right but not sure which one had low (all the way down)...thought I was gonna die when I got home that day!!!

Still haven't stopped racing...:burnout:

Treblig
 
it is called [get rid of old outboard motor gas] additive...I should have taken it to a redemption center...only one side of man was leaking ...but all intake valves show this crap buildup..the motor burned no oil before stupid mistake,i pulled and put in new plugs twice...,,and no one raced it or even pushed it...not me and I quizzed my son and he said absolutely not...I was with a guy in a 62 impala on hiway 101 in palo alto one nite racing another...he slammed it to low at 100 thinking that 283 would go faster.and we drove it home...j
 
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