Causes of bent pushrods

[Thomas]

---Timing off #1 TDE, when you should time off #8 TDC, could very easily put a valve too close to the piston's uprising, causing damaged that would come with an "interference engine". This would include a bent pushrod, but more likely a bent valve. I would check the valves, but that's just me. Backfire would be possible, but that's going to find a means of escape rather than a means of resistance, power & destruction.

---Then you have the possibility that your oil is too thick for the engine. 40W is the heaviest oil that was recommended and is still recommended from when I contacted Southland International and asked them to look for me. They said if the books said 40W was the highest, 0w40 would be the best all-around solution, 0W30 if I ran SEA30 and the usual 10W30 & 10W40 "... if that's the way you feel". I still don't, nor will I ever agree with 20W50 in an engine that runs 40W tops. Try putting 20W50 in a new car that runs 5W30 and see what happens. 30W is considered a hydraulic oil as well as our oil filters are hydraulic filters... ~hint, hint~ Too much pressure if you're running Lucas Oil Stabilizer at all, especially if using Lucas OS and 20W50 oil... no idea what you're running, just saying.

---When installing the rocker assembly, you do not line the timing mark up with 0. You line the leading edge of the counterweight on the haromic balancer with 0. That's roughly 35 degrees BTDC. Pretty much the sam ething the FSM/FRSM states... you do have them no?... and even Chitlons says "On 4-196 and 8-304, 345, 392 engines turn the crankshaft until leading edge of balance weight on crankshaft pulley is aligned with the zero degree mark on the timing indicator before installing rocker arm assembly". The reason is that this will be the lowest possible area on all* lobes, so there will be the least amount of force on the components when installing... against the rediculous theory behind timing that recently included the misplaced pi... pi... ~ahem~... NM... that is 35 degrees further than you need to be, which brings you to the top of a few lobes.

-... It could very much be that the pushrod was seated on the edge of the lifter and not on the plunger cap itself... then again, it could be from installing the rocker arm incorrectly, the wrong oil, incorrect timing, heavy load... or too heavy a foot.

---Oh, and next time you drop a lifter into the valley, try a flexible claw retrieving tool or use that magnet to try and pull the lifter into view and stand it up so you can get the magnet on the flat or cup and pull it straight up and out. Use a narrow magnet with a rubber cup around the sides and the side of the magnet won't be so easy to stick to the lifter bore or grab the lifter. When you use a lifter tool, understand that a good engine has just enough room for the lifters to sit in the bore and there is no side-to-side slop, so... you will have to sort of chisel away at the varnish that is on the bore so the lifter will come out. Pull and push the lifter to break down the varnish, don't try and pull it the first time. That will cause even the best of lifter tools to lose grip of the lifter. There's not much for them to grip in means of a groove... if the retaining spring sits in the groove as well. At best, you have about 1/32" of a lip to grab. the lifter will fall away if you don't work with it. Haste makes waste.

[Jay Tabor]

ih engines arent interference engines, says so in manuel.
way advanced ignition timing has caused bent push rods, seen it, fixed it.

[phurst]

Well, when I got the rig, timing was set at 32* TDC with no vac advance, presumably to bump the idle up due to the wires being in the wrong order. Knocked like hell the first time I tried to drive it. The PO only put 20 miles on it before getting rid of it to me. Sounds like it's either that, or the swapped plug wires. Either way, new lifters and pushrods going in when the rain stops. I guess we'll see how it goes.

[Jay Tabor]

what I deduced from the things i found when the scout came to me for repairs, homeboy had been cruising the freeway and went to pass, during down shift-acceleration . .. things went bangedy bandgedy bang
found half the cylinders had bent pushrods and some had the p rod sticking thru the rocker arms!
I thought and thought and looked and looked for da answear...hmm
something told me>>>>>>> HEY CHECK THE TIMING!
SO i did, the guys had set the static timing to about 20 -30* btdc,[ or more cant remember the nightmare details] something like that.
so i added total mechanical advance and total vacuum advance to the static timing and looking at the cam/valve chart I could see that the sparkplugs were firing while the intake valve was still OPEN.. and the piston was a long ways from tipperary . .
so what i figured was- seeing as how it was mostly all intake pushrods bent to look like pretzels..................... and stuck thru the rocker arms . . . .
CARNAGE.........

that the spark was happening way too soon and the igniting gas was slamming the valves shut and so the valves got pushed up to the seat faster than the pushrods could get out of the way, and whammo!
after i set ricky racers engine timing back to 5* btdc where ITS SUPPOSED TO BE, they drove off in their scout happily ever after..
I had checked for valves being stuck-nope-
broken valve springs-nope...
valves seating- yep..
snap-on combination wrenches in the cylinders -nope....
had oil, good flow to top end...
nothign wrong with cam- that a peek down thru the heads at each lobe could determine..
good compression in cyclanders- yep.
replace a half dozen rocker arms and pushrods and a miscellaenous lifter or two . .
things were fine in the rocker arm assembly set up and op..

so I feel that it was way advanced timing that caused the carnage . .