Help...Push rods broken... - Team Camaro Tech
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post #1 of 13 (permalink) Old Jan 30th, 01, 12:39 PM Thread Starter
 
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I am rebuilding a 454 for my camaro. Rebuilt heads,RPM kit, springs,PC valve seals,new bearings. I had the distributor 180 degrees off when I first started it. It back fired a couple of times before I relized what was wrong. Would this be the reason I broke 3 push rods?

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post #2 of 13 (permalink) Old Jan 30th, 01, 01:01 PM
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Freddie
 
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Did you check the rocker arms to see if they are binding against the studs and did you check to see if the valve springs are coil binding (stacking up solid)? You may have the spring retainers hitting the top of the valve guides. I hope you checked the valve to piston clearance while you were building the engine. These are common problems when installing a larger cam. You didn't give any cam specs so I'm assuming you put in a larger one. I don't know if a beckfire can cause broken pushrods, I've never seen it happen.

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post #3 of 13 (permalink) Old Jan 30th, 01, 01:15 PM
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I have never seen an engine actually break a pushrod...they always seem to bend. Where did they break? Just curious...but I seriously doubt the backfire broke the pushrods...sounds like something is binding. Just fyi, if your using stock big block springs and rotaters, they wont handle much more lift than a stock cam without stacking solid.

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post #4 of 13 (permalink) Old Jan 30th, 01, 01:23 PM Thread Starter
 
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I ordered 1.72 roller rockers from Comp Cams.the cam is the Edelbrock RPM cam(560/573 lift). The springs are also Edelbrock matched to the cam.So I don't think they are binding.
I did not check valve to piston clearance. I figured It should not be a issue. The pistons are stock. Should I check this, How do I ?

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post #5 of 13 (permalink) Old Jan 30th, 01, 01:25 PM Thread Starter
 
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Also, I did turn the distibutor around and the car started up and sounded pretty good.

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post #6 of 13 (permalink) Old Jan 30th, 01, 01:31 PM Thread Starter
 
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They all were bent , and broke on the cam end.About 2 inches up. They were all on the intake side.
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post #7 of 13 (permalink) Old Jan 30th, 01, 05:44 PM
 
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Might want to pull your heads and look for bent valves, but I hope not. pdq67



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post #8 of 13 (permalink) Old Jan 30th, 01, 06:09 PM
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Distributer in the wrong position will not bend/break pushrods. Valves hitting the pistons will, I bet this is what happened. Checking piston to valve clearance is a must. Pull your heads, I don't think you will like what you find.

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post #9 of 13 (permalink) Old Jan 31st, 01, 10:44 AM
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Make sure your rocker arms are not coming in contact with your valve covers!!
look for marks on the underside
I've seen it before with rev kits and such with low profile valve covers
John
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post #10 of 13 (permalink) Old Jan 31st, 01, 02:44 PM Thread Starter
 
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I ordered some chromolly pushrods today. I will get to the motor this week end . Thanks for the input...I hope it's not a clerance problem...

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post #11 of 13 (permalink) Old Jan 31st, 01, 03:10 PM
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Bill
 
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Rag,
Very rarely can you replace the stock springs on a rat motor without having to do some machine work. You usually have to do away with the rotators, and definitely check for coil bind. Either that or you had the valves adjusted way too tight. The pushrods bent because of some type of mechanical interference. The bent / broken pushrods, or the misadjusted valves, is what caused the backfire. No insult intended but I think you need to find someone who really knows what they are looking for when you put it back together. It probably bent some valves by the sound of it. Its easy to tell, just take all the rockers off and see if any of the valves are down lower than the rest. If so its bent.
Hope this helps,


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post #12 of 13 (permalink) Old Jan 31st, 01, 03:34 PM Thread Starter
 
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I had the heads done at napa. They installed non-rotator spacers for the springs,Installed .050 under valve locks, cut the valve guides down to install pc seals, installed new exhaust valves , performed a 3 angle valve job and shaved very little off the bottom of the heads.
Could a timing problem do this kind of damage???

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post #13 of 13 (permalink) Old Jan 31st, 01, 06:25 PM
 
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The only timing problem that could cause this type of damage is if you installed the cam improperly. If your lifters were adjusted too tightly also. Or the other types of binding/restrictions described above. Distributor timing will not cause this, it is merely electrical. Distributor timing only causes spark at improper times resulting in unburned gases exploding and backfiring through the opened valves.
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