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By M_S - 18 Years Ago
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Yesterday, I went to start the car ('56 'bird, 312, fordo) and heard a metal 'crunching' sound as it cranked. It lit off and ran extremely rough so I shut it off and went to investigate. I removed both valve covers and saw one rocker motionless when I cranked it over. I removed the rocker shaft and found that the pushrod looks a bit like a boomerang.
My first thought was to straighten the push rod (just to test with), re-install and see if it happens again, and if not, buy a new one and go my merry way. My better judgment told me to contact the experts first for recommendations.
I am concerned that the valve tapped the piston since it was stuck partially open. I tapped the top of the spring/retainer/valve stem with a rubber mallet and it does not seem to be stuck. I am also concerned that the tappet is stuck, but I will test this when I can get someone to turn the car over for me.
I have heard that the stock Y pushrods are a weak link and was hoping that this one just gave up on it's own, but the more I think about it the more inclined I am to believe that the tappet stuck (how else would the rocker hold the valve in the open position?).
Any and all comments are greatly appreciated.
(btw, motor internals are all original w/approx. 50k on them)
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By MoonShadow - 18 Years Ago
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I don't like the "crunching" sound part? I would try straightentinf the pushrod, put it in, and bump it over with a start button (attached to the solenoid). Watch the valve action. If it seems to open and close ok replace the pushrod and try it. Is your engine modified with big springs? If so you need to go to tubular push rods anyway. Hope this helps. Chuck in NH
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By M_S - 18 Years Ago
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I did as suggested and took my frustrations out on the bent pushrod until it submitted, re-installed everything and turned it over. Everything seems fine so far, no funny noises, all rockers rocking, and me feeling much happier yet confused as to how this happened. The car was having a hard time starting, but I don't remember giving the pedal more that three pushes (usually takes two when it is cold) so my guess is that I did not hydraulic that hole. The motor usually never sees any hard use and I have never had it over 4500 rpm. Any other thoughts as to how I (or it) did this so I don't do it again?
My next questions are regarding the repair. Given the light foot I drive with, do any of you see an advantage upgrading to hardened pushrods? Should I just replace the one? Other than taking the plugs out of the rocker shafts and making sure everything is clean is there anything else I should do with them?
Thanks in advance
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By paul2748 - 18 Years Ago
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Do what moonshadow said - go to the tubular pushrods if you don't already have them. I just got some NAPA numbers for them
Short 215-4048
Long 215-4041
I haven't checked these numbers out so I don't know if still available and what the lengths are. If not, I am sure Mummert has them.
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By Ted - 18 Years Ago
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A valve momentarily sticking open upon start up can be related to the engine being inactive for a period of time and a valve then seizes in the guide from condensation rust or old fuel buildup (varnish) when trying to start it after this inactivity. Something that comes to mind is the fuel. Is the fuel old and if so, it could have potentially built up a layer of varnish on an intake valve stem and it simply seized momentarily as a result. You didn’t mention if this was an intake or exhaust valve but with 50K miles on your engine, this is just a shot in the dark. Freshly rebuilt heads are more susceptible to this as the guides are tighter and less tolerate of any kind of buildups on the stems. Like the others, I’d suggest upgrading the stock pushrods with a later model set of tubular ones.
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By M_S - 18 Years Ago
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Ted, I usually drive the car 3-4x/week. It was stored and only started a couple of times a year before this, but I have been driving it regularly for about a year.
I ordered a set from NAPA using the part #'s listed above (thank you), but am not sure if they are tubular. I would have just ordered from Mummert to avoid the confusion but he said it would be at least 2 weeks before he would know when he was getting more in.
Paul, you state that the NAPA #'s are for tubular but their catalog lists them as solid. They may mean just the cup and ball and not the rod itself, but if anyone can confirm, it would be appreciated. The diameter on the new rods is .310 as opposed to .250 on the originals. The diameter coupled with the three piece design makes me feel certain that they are tubular.
Just in case anyone was wondering, the manufacturer is Clevite.
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By paul2748 - 18 Years Ago
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MS - sorry, I don't know any thing more about the pushrods. The numbers were posted on one of the car sites I look at and as I said before, no experience with them.
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By Hoosier Hurricane - 18 Years Ago
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MS: The 4048 pushrods are tubular, I have been using them for years. As you noted, they are made by welding a ball and a cup on the ends of a tube. The diameter further validates their construction. John
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By PF Arcand - 18 Years Ago
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Is it possible a lifter hung up momentarily? Would it have the same result? And would a fuel stabilizer, like "Fresh Start" from Briggs & Stratton be a good idea? My engine has one odd pushrod, so the previous owner probably had the same problem..
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