bent pushrods

[fryedaddy]

i took my valve covers off to check my valves and i noticed some bent pushrods,two or three on each side.my 428 is new,maybe 1000 miles.i noticed a loss in power lately and noise i thought was a header leak,but it must have been the push rod problem.what could be the cause,backfire,timing,valve adjustment,pushrod length?i didnt ask the engine shop if the valves were adjusted when i picked it up.

[machoneman]

Ouch! Bent p-rods are caused either by interference or insufficient clearance. Interference can come from the valves hitting the pistons due to over-revving, weak valve springs or not enough valve to piston clearance. These are the usual if not only causes. On clearance, new valve guides or re-worked guides may have too tight a grip on the valve stems, hanging open the valves when they should be closed or are closing and the valve head hit the piston tops. There are more reasons that these btw for the bent p-rods.   

If you paid an engine shop as it sounds, I get it back to them ASAP and get them to diagnose the issue and fix it for you for free since it sounds like they did do something wrong.   

[fryedaddy]

i may have overreved it a while back.it dont smoke or knock or nothing.i wonder if it will be ok if i put new pushrods in it and use my rev limiter from now on

[machoneman]

You can try it as many have. What I'd do is add new rods, take a short low rpm spin, park it and do a compression test (or leak-down if you have the equipment).
Why?
It's to check that no valve heads are bent from collisions with the piston tops as a bent valve head will often break pretty quickly, leading to major carnage. Write down your PSI #'s for each cylinder too.

[jayb]

+1 on what Bob said, replace the pushrods and then do a leakdown or compression check.  If its a new motor and it has some significant leakage, probably the valves are bent.  Hydraulic lifter pump-up or overrevving so that the springs lose control of the valves can lead to piston to valve contact and bent valves and pushrods, or bent or broken rockers.  It would be a good idea to take a very careful look at the valvetrain components.

[fryedaddy]

i ended up with 4 bent rods all odd 1357 intakes.thanks i will inspect all of the valve train. my push rods are around 9 3/16 length i see so many sizes i hope thats the ones i need

[fryedaddy]

i called the engine shop,he asked what kind of rockers i have,i told him stock adjustables and he asked how far down my adjusting screws were.he asked if they were around half way in.i told him they were at least 2/3 in.hes going to order me some new rods.he is going to look it up,he said i might need a little longer push rod since they are screwed in so far.i havnt found any more damage.that was a cheap set of rods.

[FloridaMack]

Seeing as its all intake pushrods that bent it would scare me a bit. Intake valve is bigger and more likely to make contact with the piston.

[fryedaddy]

im not too worried my dad and uncle had a wrecker with a 390 in it,they would pop wheelies pulling cars out of tight places and i remember they bent a few pushrods doing it but they never damaged the engine other than a pushrod or two.i will know when i put the new ones in. i had a big backfire that blew the oil cap and dipstick off,that may have done it

[fryedaddy]

i checked the dia. of the pushrods with a caliper and it was only .310 in diameter and the wall thickness is only .050 does that seem small. they are littler than some others ive had. they were made by a company named madd dogg racing.has anyone heard of them.some of the cups were loose too,and fell off

[fryedaddy]

after giving those pushrods a good look,4 are bent fairly bad,4 were slightly bent,i asked Larry Sneed at S&G machine in Bristol and he said my valves should be ok,he didnt think i would have bent a valve head that would break off later.i sure hope not,but im still going to do a compression check when i get it back together because it will eat away at me wondering if i dont find out for sure,and it could eat away at my pocket book too

[C6AE]

I would be more than a little curious at exactly why they bent.

If it is an interference issue the guides/valves are likely scored. If the valves are not bent it would be a surprise to me as they are pretty delicate that way. Over-revved or seized, either way they hit the pistons. I would have to look, pull the valves and put them back in the grinder to prove they are straight. These valves may seal up again with the pressure of combustion, but it seems likely this will raise it's ugly head down the road a ways, just after the "warranty" is past...

[fryedaddy]

theres no warranty, my uncle was building me a 428,he was a great engine builder,but he got sick and died before he got finished with my engine.its all new but i had to go to my uncles house and pick up the parts,all the engine shop did was put my stuff together for me,i didnt buy anything off them,and my uncle had bought all my parts and machine work and his wife would not let me pay her anything.so i lost my uncle and gained a free 428 in the process,so i cant start pointing fingers over this. i took a cup off one of the pushrods and the wall thickness of the rod was only .050 thick,that dont seem thick enough for a high performance app to me

[fastback 427]

My first high compression 390 built over 20 years ago bent push rods like crazy. It would only do it if you stabbed it off idle. Some were so bent we had to pull them out with a claw hammer . A couple times a lifter would pop out and instant loss of oil pressure. Drove that motor hard for ten years with no other problems. A set of comp push rods and all was well. We pulled it apart and there was no sign of valve to piston contact anywhere. Must have been lucky or young and dumb, I wouldn't do that on my 427 now without checking.

[fryedaddy]

thats the kind of stories i like to hear.i dont care much for negative comments