hello i am working on a 1986 f-150 351 w. the motor was pull for a refresh nothing to special then things got fun. stock block .30 over bore. stock heads with screw in studs comp guide plates and roller tip rockers and a eddy intake where all on this motor before the refresh tare down. motor went to the shop to get looked over. while it was there a stroker crank got throw into the mix. everything checked out fine according to the machine shop. put the motor together a friend was helping with the assembly. the rockers where not tightened according to comp specs. they where just tighten down. motor has never ran but has been cranked. didnt sound right so a valve cover came back off for a retime. the number one intake valve rocker was off the tip of the valve and the pushrod was bent. all rockers where taken back off and about 8 where bent a mix of intake and exhaust. some where bent real bad others just a little. new pushrods have been put in and the rockers left really lose. on turning the motor over when the valves open the push rods get really tight. the block nor the heads have been decked. i am at a lost here everything is the same other than the crank and cam. could have the timing chain been installed wrong? or maybe with new cam and such could the push rods be to long? thank you for your time.

 

There are no stock 351 heads with screw in studs so what heads do you have?
What cam is in the motor?
Stud mount rockers require a specific lash procedure they're not just tightened down, and you have to know that you have the correct length pushrod to start with.

 

yes i understand that no stock heads have screw in studs. these have been machined to have them with guide plates. i also understand that the comp roller tip rockers have a lash procedure to them that is why i stated that wasnt done. i am wondering if this is what is causing my push rods to bend. i do not know the specs the cam is. it is nothing to radical. all the valve train was in the motor to begin with.

 

New cam, new crank--hhhmmm.

Could be piston to valve issues, could be coil bind on the valve springs, could be wrong length pushrods, or a combination.

Back to checking the basic measurements methinks.

Any other interference or possible contact points should be checked as well.

 

Well if it was all in the motor before you must have something setup wrong to be bending pushrods. Was the cam installed straight up with both timing set marks pointing towards each other?

 

IMHO, sounds like plastic gauge wasn't used to check clearances...and somebody's math may have been off (personally I always use plastic gauge)

 

cam was installed straight up. i did use plastic gauge on the bottom end. i am off to talk to the machine shop today.