Bent Push Rods

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jimbo

jimbo

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So, I picked up a 76 LA 360 long block off Craigslist a couple years ago from a rolled Powerwagon. Low miles on a rebuilt motor, 20k or so and stored inside since pulled. $140
That said, I needed a core anyway so I got it home and on the stand and started looking it over. The oil pan was only held on with a few bolts for transport as were the valve covers. Upon inspection everything was super clean and the only noticeable issue I saw was the new timing chain was a bit saggy and a few (3) push rods were upsized from the rest. After closer inspection inspection a total of 3 more of the smaller push rods were slightly bent (+or- 1to3°). As a result I pulled them all and installed a new set of the larger diameter push rods. I have since started putting it together for with a car oil pan, '68 340 cast intake, new balancer, water pump etc.
So I'm on the fence now about tearing it down completely, as I did not build this motor and do not know it's history. Best case, I won't need any machining and will get by with rings, bearings, and gaskets. Worst case it's garbage, nice clean garbage. I have built several mopars from /6, 318, 340, 360, and a HP 383. I am well aware of the cost in time and money involved and I'm not planning to sell this to someone else.
I could use a few other opinions than my own, thanks.

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Take the rocker arms off and tap on all of the valves to make sure that they are not stuck and caused the bent push rods...

Then install them and turn the engine over to make sure that the push rods are not hitting the pistons...
 
jimbo said:
So, I picked up a 76 LA 360 long block off Craigslist a couple years ago from a rolled Powerwagon. Low miles on a rebuilt motor, 20k or so and stored inside since pulled. $140
That said, I needed a core anyway so I got it home and on the stand and started looking it over. The oil pan was only held on with a few bolts for transport as were the valve covers. Upon inspection everything was super clean and the only noticeable issue I saw was the new timing chain was a bit saggy and a few (3) push rods were upsized from the rest. After closer inspection inspection a total of 3 more of the smaller push rods were slightly bent (+or- 1to3°). As a result I pulled them all and installed a new set of the larger diameter push rods. I have since started putting it together for with a car oil pan, '68 340 cast intake, new balancer, water pump etc.
So I'm on the fence now about tearing it down completely, as I did not build this motor and do not know it's history. Best case, I won't need any machining and will get by with rings, bearings, and gaskets. Worst case it's garbage, nice clean garbage. I have built several mopars from /6, 318, 340, 360, and a HP 383. I am well aware of the cost in time and money involved and I'm not planning to sell this to someone else.
I could use a few other opinions than my own, thanks.

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Don't forget to install the oil slinger before putting the timing chain cover on...
 
The oil pan is off maybe plasti Guage rods and mains, maybe compression leak down being as it’s unknown to you. The pushrods not being true could have been that way when installed. If it’s all good I’d fire it up. It does look very clean inside. As far as slack on timing chain and gears, it seems the new stuff is getting kind of sloppy right out of the box.
 
krazykuda said:
Take the rocker arms off and tap on all of the valves to make sure that they are not stuck and caused the bent push rods...

Then install them and turn the engine over to make sure that the push rods are not hitting the pistons...
Click to expand...

I can guarantee sitting right here at the kitchen table that the pushrods are not going to hit the Pistons. Now I'm not saying the valves might not hit the Pistons but for sure the pushrods will not. lol
 
Do you know the specs on the cam? The retainers could be hitting the guides bending the valves. If you have a cam card degree the cam.
 
I was wondering if the springs are too tall for the cam, but like I said it's all buttoned up now. I installed the oil slinger and the engine turns freely.
 
I don't know 360's well. Do they come OEM with roller timing chain? If not may indicate a good quality rebuild.
 
dano said:
Do you know the specs on the cam? The retainers could be hitting the guides bending the valves. If you have a cam card degree the cam.
Click to expand...

More of a chance of bending the pushrod than a valve unless it hits a piston when a retainer hits the guide, I would think.
 
Also check the rocker arms, they have an offset that may affect the pushrod clearance with the head if they're install incorrectly.
 
I would check everything, especially on the top end. Cam specs, spring pressures, bent valves, all of it.

When I bought my '71 Dart it was running pretty rough. I took a look at it and found similar stuff, a couple of bent push rods, a couple of bent valves, a couple of pistons with valve strikes. Everything in the bottom end was stock with 80k+ miles, timing chain was new. I figured they replaced the timing chain when it went south and missed the valves and pushrods. Replaced two bent valves a few pushrods, buttoned it all back up. Ran great til I shut it down and started it again, timing was way off. Checked all kinds of stuff, ended up pulling the engine because it was pretty worn anyway.

When I tore it down I found out some mouthbreather didn't put a woodruff key in the timing gear when they installed the new timing chain. So the timing gear was slipping on the cam. The bolt was enough to hold tension when it was running, but on shut down or start up it was moving.

Good luck!
 
I'd pull it completely apart and check everything. Check for all the oil galley plugs to be installed. Don't forget the one in the passage between the oil pump and the oil filter. Of course, check the bearing clearances, and rods and pistons are facing correctly, and rod caps are oriented properly. Make sure the cam bearings are intact and installed correctly. Check TDC mark on dampener, degree cam. Check spring height and clearances for cam lift. Check to make sure you have proper lifter preload, and rocker shafts are oriented correctly. When you're all re assembled, prelube and check for good oil pressure. I may have forgotten a few things that somebody can point out, too.
Bottom line, it's so much easier to check it out thoroughly, now, than gambling on it being done right already.
 
I'm with some of the others and has kinda been my thinking right along,its out now, go through it so you know everything is ok.With no history on this no way I would not, for the cost and already finding some issues and not know why?? Peace of mind
 
I'd at least pull the heads and check the bores, piston tops, head surfaces, valves, deck surfaces, etc.

The chain may be poor out of the box or they may have line-bored the block and sunk the crank in a bit.

I'd for sure replace the chain and rework cam timing accurately. You can be sure the cam is now retarded a few degrees with that amount of slack, and if the pistons are the stock low compression stuff, that is not going to help.
 
Now is the time.
Pull the oil pump cover and check for damage, grooves, etc.
"Feel'' the rods for slop.
Remove and plastigage #1 rod bearing and #1 main bearing. [The last ones to get oil]
Change timing chain.
Remove and check rocker shafts. It looks like the pass. side rocker shaft is on wrong. When looking at the head, the rocker arm shaft notch goes down and to the left.
Pull the heads. Look for marks from valves hitting the pistons.
Replace all pushrods.
Some valves could be bent, especially the intakes.

That should keep you busy for a while.
 
most likely guides are varnished up
but heck check everything
i missed that rocker shaft
renolds or ewiss chain, maybe a magnum tensioner
 
Last edited:
pt70 said:
Now is the time.
Pull the oil pump cover and check for damage, grooves, etc.
"Feel'' the rods for slop.
Remove and plastigage #1 rod bearing and #1 main bearing. [The last ones to get oil]
Change timing chain.
Remove and check rocker shafts. It looks like the pass. side rocker shaft is on wrong. When looking at the head, the rocker arm shaft notch goes down and to the left.
Pull the heads. Look for marks from valves hitting the pistons.
Replace all pushrods.
Some valves could be bent, especially the intakes.

That should keep you busy for a while.
Click to expand...


Good eye, catching the passenger side rocker shaft being on backward.
 
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