Push rods bending on 400
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U guys r a lot of help I dont mean to sound ignorant but all jokes aside this is all greek to me I run a lawn care and firewood business in the winter.No patience for working on vehicles. I just needed some differnt ideas on what might be going on here. The guy that works on it for me looks like he would of tried something differnt by now.I think i will hav someone check valve spring clearence for coil binding and go from there.According to comp cams the smallest cam they offer say stock springs will not work. Thank all of u for the help.
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From: chicago burbs
i just found another possible cause, also mechanical interference.
1969 Ford Fairlane OHOnewsletter picture | SuperMotors.net
i have noticed while washing up stock rockers in the solvent tank, that there are different stampings. the difference i found is in the fulcrum area of the rocker body. the way the body is stamped, an increased lift cam might cause the fulcrum to ride up on a section of the body that is not smooth with the rest of the fulcrum travel area, if you understand that? if the fulcrum did travel onto that area the rocker would freak out at max lift. but like i said, not all of my stock rockers were not stamped the same, i didn't take notice wheter or not they had the smooth or ledge top edge. YMMV
1969 Ford Fairlane OHOnewsletter picture | SuperMotors.net
i have noticed while washing up stock rockers in the solvent tank, that there are different stampings. the difference i found is in the fulcrum area of the rocker body. the way the body is stamped, an increased lift cam might cause the fulcrum to ride up on a section of the body that is not smooth with the rest of the fulcrum travel area, if you understand that? if the fulcrum did travel onto that area the rocker would freak out at max lift. but like i said, not all of my stock rockers were not stamped the same, i didn't take notice wheter or not they had the smooth or ledge top edge. YMMV
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From: Longwood, Fl
I wonder if the different mfg's of rockers was at the root of my problem when I put a crane 260 RV cam in my 76 460 at ~125K. It really sounded terrible with all the noise from the rockers when I cranked it. I thought it was because a wear pattern had developed between the sled and the seat in the rocker. I dont think the cam had enough lift for the problem shown in the link, but maybe different mfg's created the seats in the rockers differently so a similar problem was created inside the rocker. I had to change out for a set of comp's roller tips. No more noise 
This is the first indication I have seen that noise was from something other than wear patterns. TX for that article. I wonder if there is any other info on rockers there.
This is the first indication I have seen that noise was from something other than wear patterns. TX for that article. I wonder if there is any other info on rockers there.
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Hi heres what happend to me. I had a 351m in my 78 f150. I installed rv cam, headers,aluminum intake, gear drive,truck avenger carb,hei dizzy anyway I got a set of redone 351m heads cheap off ebay. I put them on and every week or so I would bend the same pushrod. I think it was intake anyway. This happend a coupel of times so I decided to pull the motor and rebuild it. Made it a 410 put another $600 into it (found out I had a bent connecting rod) Thats nothing to do with bent pushrod. Anyway the same thing happend. What I found out is since I diddent check the installed valve spring height I did not know that the valve seat had to be ground deeper in the head on that one valve. Well when that happens it changes the pushrod lenght but just for that valve. so I had to get a -.060 shorter pushrod. They are still available from summit racing. I think there made by copetition cams and you can buy them single.
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From: chicago burbs
shims won't change the lift, all it will do is raise the plunger in the lifter and move the contact patch on the valve tip. all that has changed is the geometry. because the plunger takes up the difference that the shim caused the lift will be the same.
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From: Eastern Ohio
Someone on this forum said " I have to quit posting when I get drunk" , and I am trying to find him. He is my hero.
The number one cause of bent pushrods is coil bind. I disagree with the statement that it will occur at all rpm. At higher rpms, the lifters will travel higher than the cam lobe. It's called momentum. The lifters,pushrods,rockers, and valves will accelerate past the advertised lift. If you're close on specs, coil bind will occur.
I have a pushrod bending problem with my 400 which, at this time, is unresolved. I first blamed it on my son for overreving the motor.
After a hell-of a-fight, I went back to basics. Somewhere, I posted a reply on this subject ( back to the drinking issue) . The old way of setting valves @ 90 degrees doesn't work because of the ramps on aftermarket cams. You have to plot the cam card on graph paper and set the valve at 180 degrees opposite lobe peak, or you may be setting your lash on the ramp.
I may be old and full of it, but that's how it do.
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Very true, i had trouble setting 0 lash on aftermarket cams, the lifters seem to be charged and the push rod set to rest on the base circle of the cam. But still had opened valves on rest position meaning i was setting my lash on the ramp...
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Posting Guru
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Very true, i had trouble setting 0 lash on aftermarket cams, the lifters seem to be charged and the push rod set to rest on the base circle of the cam. But still had opened valves on rest position meaning i was setting my lash on the ramp...
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Bending pushrods in a 1978 F250 400M
I have been having trouble bending the lifter rods on cylinder #8. The engine would run just fine for start up and around town but as soon as a load was placed on it the valves would stick open and bend the rods. The heads were freshly rebuilt with all new valves. I decided to do a bit more looking into the problem and discovered that the rocker and cocker arm were installed backwards. On the original rockers they have oil lines that run at an angel toward each other and on the rocker its self it has matching oil lines. If they are installed opposite each other it creates a were point that heats up and sticks when they are placed under a load (accelerating or hill climbing). I replaced the old rockers and pivot and have not had any trouble since. I hope this helps.
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