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surprise under the valve cover

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Billy C View Drop Down
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    Posted: 17-December-2010 at 2:29PM
Hey kids,
Yur gona love this. So ever since I can remember I have been getting a tap in my mostly stock 74' 460 at around 2.5k rpm and up in my 72' GTS. So it wasn't really getting worse but it was starting to really bother me now that I am not a total newbie and know sounds like this are not usually good. I have also been having some mystery issues and was too lazy and fullish to check the valve train. So I finally pulled the valve cover off the side I thought the sound was coming from and checked the rocker arms and a little surprise was waiting for me under cylinder #2 exhaust rocker.




Gotta love it!! Clap  I drove 800+ miles with it like this, and the car ran great other than that sound. Still as could be at idle. That is a ford 385 series motor for you. I remember when I got the car about a year ago, before I tore it down to frame, I had two plug wires switch but quickly solved the problem. Still makes sense that one drive down the street with two wires switched would cause this. I ordered a few new ones just in case the problem has a buddy . The rest of the rockers seem good. Very little to no play. Who would have thought....

Anything else I should look for? I plan to change oil and filter too.
-Billy Conturo
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Billy C View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Billy C Quote  Post ReplyReply Direct Link To This Post Posted: 19-December-2010 at 1:57PM
Wow! I replaced the rod and it runs noticeably smoother, I still here a slight tap though. It is so faint I am thinking it may not even be motor, or maybe just some old age lifter/valve train noise??
-Billy Conturo
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GranTorinoSport Quote  Post ReplyReply Direct Link To This Post Posted: 26-December-2010 at 1:20PM
Billy C,

I've read your post a couple of times regarding your pushrod find, but I'm at a loss for any good comment or advice. I can't say I've ever heard of that being any sort of widespread problem.

As long as you know what the cause was, and was able to correct it, it should be fine.

Did the pushrod simply jump out of it's seat? Or did it just warp under normal use?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Blueoval76 Quote  Post ReplyReply Direct Link To This Post Posted: 26-December-2010 at 2:30PM
If there is still a tick then it is possibly a colapsed lifter and since there is space in between it bent the pushrod. I would just drop a lifter in that one and you should bne fine or I guess you could tighten it till all the gap is gone.
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Billy C View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Billy C Quote  Post ReplyReply Direct Link To This Post Posted: 26-December-2010 at 7:13PM
The push rod was fully functioning but bent. I guess what happened was when I had the plug wires mixed up the spark plug fired right before the exhaust stroke, that un-burned mixture ignites un-compressed and wants to expand a bit right as that valve tries to open holding the valve closed enough to effect the weakest link in the system????? I don't know how else it could have happened.. Push rods are HARD.. I can't even bend it if I try. Don't know how else to explain it.

It was scraping on the inside wall of the block, since they are hyd. lifters (stock) there wasn't a noticeable sound at idle and low revs because that space was compensated for by oil between the lifter and cam. When the motor would rev high that oil wouldn't have enough time to fill that gap resulting in major slack in the push rod, clicking back and fourth. 

Now, the rocker arm is tight so I wasn't really too worried about it.. how hard is it to pull a lifter and replace it?


Edited by Billy C - 26-December-2010 at 7:21PM
-Billy Conturo
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Rockatansky View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 26-December-2010 at 7:47PM
valve float is probably the most likely cause to bend a pushrod.
 
over revving a weak valvespring(which can happen at ANY rpm being that the spring is weak and not up to spec) can cause the pushrod to find itself between parts moving not in harmony. the lifter on the way up & the valve also on the way up, something in the middle's gotta give. the float could also involve piston to valve contact, adding more force to the weak link in the middle
 
sometimes with a fresh set of heads thre guides will be sized too tight, the valve sticks in a guide when the temps come up & seize the valve, same result. usually more noticable than just a bent P-rod because the valve is hung open causing an obvious intake or exhaust miss while many times just a bent P-rod will still operate the valve enough so that the cylinder isn't completely dead
 
make a note of which P-rod/valvespring it was that bent & keep an eye on it if it starts running 'funny' in the future
 
did you pull all the P-rods out and roll them on a flat surface? might not be only one


Edited by Rockatansky - 26-December-2010 at 7:49PM
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Billy C View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Billy C Quote  Post ReplyReply Direct Link To This Post Posted: 26-December-2010 at 7:53PM
No, i plan to do that tomorrow if I get a chance. thanks. I know another is very slightly bent. I can tell when I roll it seated.

Thanks
-Billy Conturo
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