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Old August 13th, 2011, 07:09 PM   #1
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Bent Push Rods??

Ok-finally opened up the '65 425 after seeing AllanR's post, I figured I would see if my motor was good to go.

Well as the pics show I have 3 bent push rods in a row. What exactly causes a push rod to bend? Any other issues I should be looking out for?

Thanks
d1
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File Type: jpg Bent push rods2.jpg (99.4 KB, 55 views)
File Type: jpg Bent push rods3.jpg (86.4 KB, 49 views)
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Old August 13th, 2011, 07:17 PM   #2
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The most common cause is stuck valves.
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Old August 13th, 2011, 07:21 PM   #3
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Most likely a timing issue the valves tried to open on a cylinder when it was all the way up. sometimes hydralic lifters get stuck and have no give in them. and could be other stuff but three in a row i would think it was timing that done it.

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Old August 13th, 2011, 08:19 PM   #4
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Quote:
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Most likely a timing issue the valves tried to open on a cylinder when it was all the way up. sometimes hydralic lifters get stuck and have no give in them. and could be other stuff but three in a row i would think it was timing that done it.
Stock Olds engines of this vintage are "non interference" engines. This means should the timing chain jump the valves should not contact the pistons. Therefore a lifter would not cause bent pushrods either.
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Old August 13th, 2011, 09:03 PM   #5
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WOW when you said bent I figured you put them on a flat surface and found a few with a little curve to them. Not actually "BENT".

I can only see stuck valves causing that. Are sticking valves common on olds engines?
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Old August 14th, 2011, 09:49 AM   #6
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The only time I bent a pushrod(s) I over revved it.......
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Old August 14th, 2011, 10:04 AM   #7
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No, Olds are not notorious for bending pushrods....as any engine thats been sitting things rust and things get gunked up. I had a 66 Sfire that had been sitting a long time. I bought it and wanted to see if I could get the engine going.....gas in tank smelled a bit like varnish but I added some fresh gas and got it running....seemed to run pretty good too. tbhen I left it sit for a few months and when I tried to start it again I bent a few pushrods like the ones above. Possibly engine heat and that varnish created a sticky tar like goo and that is why caused the valves to stick.
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Old August 14th, 2011, 11:24 AM   #8
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Also check the valve locks. If someone put the wrong locks in, that would definitely happen.

As said, most likely stuck valves. Probably rusted together.
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Old August 14th, 2011, 03:30 PM   #9
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Didn't you have a recent thread, about having your heads worked on and getting custom length pushrods? Is this the same motor?

If so....

The heads were probably NOT properly set up for the valve lift you have. Either coil bind or retainer-to-guide (or valve seal) interference at your max lift.

If you installed aftermarket rocker arms when you did the recent work, there is also a chance they are just WRONG, and possibly binding in some way.

Check for cam damage, too.

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Old August 14th, 2011, 04:24 PM   #10
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Quote:
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Didn't you have a recent thread, about having your heads worked on and getting custom length pushrods? Is this the same motor?

If so....

The heads were probably NOT properly set up for the valve lift you have. Either coil bind or retainer-to-guide (or valve seal) interference at your max lift.

If you installed aftermarket rocker arms when you did the recent work, there is also a chance they are just WRONG, and possibly binding in some way.

Check for cam damage, too.

Lee

Nope different motor all together, but thanks for dredging up bad memories.
The "custom' push rods were for the 350 I am currently running now.

But thanks for addressing this, because I will probably wind up having to do the same thing to the 425. I don't think I will be buying an "all-in-one" kit that will accommodate the mods to the heads and block that I will probably wind up doing.

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Old August 14th, 2011, 06:24 PM   #11
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LOL, the motor in the pics looked rather nasty, so I was HOPING it was not the same!

A machinist friend of mine pointed out to me, back in the mid-90's, how it is rather insulting to a machinist when you bring in one of those "all in one" kits. The "kit" barely ever works (with the exception of some very specialized current kits, like the Patriot kits for LS motors) the way it is advertised, and usually entails enough extra work (labor cost) by the machinist to more than offset any "savings" the kit offered.

Find a GOOD shop, give them the cam specs and intended usage, and let THEM get the parts that will work!

Good luck,
Lee
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Old August 14th, 2011, 07:04 PM   #12
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Yeah, funny you mention that concerning the machinists. When I had my SBO 350 heads rebuilt, I brought in parts that I had acquired over the previous 6 months. I did this in part to save money on parts. So, when I brought them in to be installed in the rebuilt heads I was given the "we use our parts" answer. They used some of the items and told me that some items would not work and that some items could work but would cost me more in labor than if I just let them use their own resources.

It was a learning experience for sure. I took a lot for granted, but in my case I only have one machinist locally that anyone actually trusts, so I was limited in that regard, but it is good info to pass along to others. You need to communicate with your machine shop prior to obtaining parts and come up with a game plan from the start.

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Old August 14th, 2011, 10:57 PM   #13
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2 of the 3 are exhaust, and at the crossover, more heat for the valve stems to gall/stick.
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Old August 14th, 2011, 10:57 PM
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