bent pushrods - Team Camaro Tech
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post #1 of 8 (permalink) Old Jan 8th, 06, 09:51 AM Thread Starter
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vince
 
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Location: metairie. LA.
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bent pushrods

I bent 2 pushrods this morning. I adjusted valve lash yesterday. thought i did it right. I started up today and was going to verify adjustment using method of loosening till clatter, then tighten back down till no clatter. After a few minutes while i was working on driver side I heard knocking on passenger side. shut it off and noticed 2 bent pushrods. I am wondering if I need guide plates for pushrods. I have roller cam (cca-8-433-8), aluminum heads, centerbolt, angleplug, 58cc, that do not have the individual holes for each pushrod, i also have rollertip rocker arms (cca-1417-16), standard length pushrods (cca-7808-16). I bought this engine as a shortblock then started buying the additional needed parts. Any ideas?
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post #2 of 8 (permalink) Old Jan 8th, 06, 10:12 AM
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Jim
 
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Re: bent pushrods

There needs to be something to locate the rockers or pushrods. This could be the individual pushrod holes in a stock older head, a guideplate, or a self centering rocker arm. Gotta have one of the 3.





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post #3 of 8 (permalink) Old Jan 8th, 06, 11:27 AM
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Dave
 
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Re: bent pushrods

Additionally pushrods don't bend by themselves. They get bent when they run out of travel and the lifter is still going up. Either the slot isn't long enough in the rocker, valve is hitting something or spring is bottoming out. You have a mechanical clearance problem with your combination that needs to be resolved.

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post #4 of 8 (permalink) Old Jan 8th, 06, 11:47 AM
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Paul
 
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Re: bent pushrods

Is it a hydraulic roller? If not valves need to be adjusted with the engine off.

Last edited by 1969 RS/SS DROPTOP; Jan 8th, 06 at 01:25 PM.
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post #5 of 8 (permalink) Old Jan 8th, 06, 04:43 PM Thread Starter
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vince
 
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Re: bent pushrods

The lifters are hydraulic, the rocker arms i think are the self centering (they have the washers on either side of the roller tip). The springs seem to have additional room for compression when the valve is completely open. When the valves are closed there is plenty room between rocker arm and springs. I dont think i mentioned it earlier but there was a "ting ting" type of noise that seemed to be coming from the drivers side. ( opposite side of bent pussrods) I got a little nervous so i pulled the head off but everything looks fine. No foriegn materiel or evidence of anything hitting valves or pistons. I will remove passenger side head tomorrow.
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post #6 of 8 (permalink) Old Jan 8th, 06, 06:03 PM
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Don
 
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Re: bent pushrods

1) How's the valve to piston clearance?
2) Think you have some intake manifold bolts too long? Going to far into head and hitting push rod?
3) Washers on the side of the centering roller tips? What kind are those?
4) Were your valve guides recently knurled?

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

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post #7 of 8 (permalink) Old Jan 8th, 06, 06:56 PM Thread Starter
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vince
 
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Re: bent pushrods

I dont know a whole lot about the particulars of head mechanics, so what exactly is a knurled valve guide and how can it cause a knock? Years ago when i was puting this project together i did have the valve size increased from 1.94 to 2.00. I'm not quite sure what exactly was done at the machine shop during this procedure.
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post #8 of 8 (permalink) Old Jan 9th, 06, 06:23 AM
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Don
 
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Re: bent pushrods

Knurled valve guides is a cheapo way to correct excessive stem / guide wear. It involves of basically making threads into the inside of the guides. It works for a while and provides extra lubrication as the little threaded groves hold oil. This sometimes also causes problems as when the valve stem is fitted back into the hole,,, the stem head can break one of the little threads and fold it over. With a heated engine, this little particle can swell and cause the valve stem to tighten and gall thus stick the valve, either in full open or closed position. So if the force is great enuff, you will or could either bend the next weakest point with would be the push rod or it could cause the valve to hang open,, at the wrong time , thus the piston comes up and sorta closes it for you,, Not a good thing,, it will bend the valve over time or go thru the piston top.

So tapping the piston could cause the little ting sound . Oversizing the valve head would not or should not have anything to do with this . I had one such case on the knurled valve guides and it did not show up until on a long trip. Need to go back to the shop and ask questions, my guess is that if its more than 90 days old, its yours.

I am only suggesting this ,, your case may be differant. Since you have heads off, I would take each valve apart and look for trouble. Hope you dont have any broken springs that are stacking. Also becareful that the valve stem does not have a worn mushroom tip as this also will cause scratches and gouges into the valve guide area when you pull valve out. Check your seals too. Good luck

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

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Last edited by zdld17; Jan 9th, 06 at 06:50 AM.
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