Thread: Bent pushrod?

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Finally got my 5.0 Ranger to the track last night and it ran like a raped ape until I got to the 1/8th mile timer. The engine seems to have a valve clatter and there is engine vibration. A friend thinks I bent a valve pushrod or cracked a valve spring. I have spark to the cylinder. Before I start ripping the old girl apart, any thoughts?

Originally Posted by jabaker01

Finally got my 5.0 Ranger to the track last night and it ran like a raped ape until I got to the 1/8th mile timer. The engine seems to have a valve clatter and there is engine vibration. A friend thinks I bent a valve pushrod or cracked a valve spring. I have spark to the cylinder. Before I start ripping the old girl apart, any thoughts?

This happened to me when I was using stock "budget" rockers.I had pop the pocket out of one of the rockers where the push rod sits.No one can say what it is at this point ,it could be anything.
Keep all your parts in order ,and INSPECT every piece.You can find signs of things not working correctly.

Okay, I guess I'm thinking in the right direction here. The rockers & rods are stock 5.0 HO (92 Stang). I was careful not to over-rev. Threw shifts at 5,500.
I had an 8.18 (86.5 mph) at the 1/8th and clocked out with a 14.69 (91.27 mph). Not bad on 7 cylinders. Should have been in high 12's.
The part that hurts was it was a first run after 2 years of planning, building, planning again, building again. I'm sure you know how that works!

Originally Posted by jabaker01

Finally got my 5.0 Ranger to the track last night and it ran like a raped ape until I got to the 1/8th mile timer. The engine seems to have a valve clatter and there is engine vibration. A friend thinks I bent a valve pushrod or cracked a valve spring. I have spark to the cylinder. Before I start ripping the old girl apart, any thoughts?

all of the above or, stuck valve, stuck lifter maybe, if you shut it down soon enough it might not be too bad.

Turned out to be am bent exhaust pushrod on #5
and it didn't take anything out with it. I got lucky.
Will be changing out all the pushrods and rockers this week
and will see what the truck does at the strip next Friday night.
I'm looking for low to mid 12's.

Probably should figure out WHY it bent?Trick flow and Comp cams are acouple that make quality rods.

I figure, as a stock (92) pushrod, that it just crapped out with the quick revs and significant power I added. I've ordered all new COMP rods and roller rockers and will see what breaks next.......hopefully nothing.
I should have done the replacement in the beginning when it was all apart but they looked okay and, well, that was stupid. I did replace the lifters when the cam went in and didn't give much thought to the rods.
While it is now opened up, I have carefully looked at the springs, retainers and they look good.
I didn't over-rev or float a valve. I've done that in the past and what I felt and heard on Friday was not at all similar.
Let's hope this takes care of whatever happened. I think it was just a simple rod failure. Either metal fatigue or bad to begin.