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  #1  
Old 11-20-2002, 03:31 PM
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Default Get Bent, Pushrods?

Another problem from the master of disaster. I figured out why my truck was smoking! I do have oil leakage past the rings or valve guides somewhere but that was only part of the problem. I took off my valve cover on the drivers side and to my surprise it was missing a brand new intake pushrod on number 7 cylinder! I fished around and found the pushrod (luckily in one piece unlike others I have taken out before). Without any gas going in to the cylinder the plug was just loading up with oil so when the spark plug fired it was just a stream of smoke. Now that gas gets to it, it helps dissapate the oil buildup and burns it all.

Now my problem is why do I keep bending pushrods? Here are the specs...

IH (duh) 392 four barrel intake w/edelbrock 600CFM squarebore carb
Stamped rocker arms (all pivot on central rocker shaft unlike individual rockers on a small block chevy)
Hydraulic lifters
Had all new pushrods in it now it only has 15 new ones and one old one
Always bends on intake valve number 7

I am tired of having to replace this pushrod it is one of the hardest to replace because I have to take off my brake booster and master cylinder to put the lifter back in to place after it pops out of its hole because of the missing pushrod.

I asked my automotive teacher and he is at a loss. What he did tell me that high performance engines have a pushrod guide to keep them at the perfect angle all the time. Is the 392 suppose to have somthing that I may not know about?
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  #2  
Old 11-20-2002, 04:01 PM
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Default Re: Get Bent, Pushrods?

Something is "wrong" with the #7 intake.

Especially if a perfectly good pushrod "falls out"..

By "stamped" you mean one-piece "boat" style, right?

Is the #7 rocker *bent*? Or broken? (BTDT with the welded rockers)?

Has the engine been rebuilt? How's the guide seal on the #7 intake?

Either the rocker is damaged and allowing the pushrod to get loose, or maybe the heads have been off and a thicker gasket used and you're just unlucky enough that #7 pushrod is now too short sometimes?

Or else the valve is sticking in the guide, causing the pushrod to get piched - bent or shot out.

A *dead* lifter might allow things to be loose enough, I suppose - if the lifter just isn't pumping up.

I hate these problems. [img]images/graemlins/smile.gif[/img]
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Old 11-20-2002, 11:27 PM
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Default Re: Get Bent, Pushrods?

Actually I took my rocker arms in to the auto parts store when I bought new pushrods because I had no idea whether they were cast or stamped. The guy at Car Quest said they looked really good and not beat up.
By calling them "Stamped" that all the arms that push down on the valve stem are all pivoting on a central shaft.

I do have (or had) clacky lifters. I bought some of that power punch stuff (partially because I was a little low on oil) and the fact that I poured it all over my drivers side rocker arm shaft and all down the pushrods. Since then my engine surprisingly runs and sounds much better. I want to fix this problem mostly because I like the way it runs on all 8 cylinders. I can actually get my 36" tires to spin faster than I am moving on occasion [img]images/graemlins/wink.gif[/img]

My auto teacher thinks it possibly could be a stuck valve but he said I am going to have to stick a vacuum gauge on the intake manifold when I get it to pop to see if it firing with the intake valve open.

Last but not least, no this engine has not been rebuilt to my knowledge.
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Old 12-01-2002, 07:09 PM
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Default Re: Get Bent, Pushrods?

Almost two weeks later, another one bites the dust (pushrod that is). On my way to Sandlake on I-5 truck starts jolting really badly backfiring in intake running bad. Lasts about 2-3 minutes then stops, smooths out and feels as if there is an intake pushrod missing. Take off the Valve covers at Sandlake and sure enough intake on #7 is gone! I am really beginning to become annoyed. I like it when it runs on all eight cylinders but if I were to just leave out #7 I would never have any problems. I am going to buy one new lifter tomorrow and put it in place on the intake for #7.

I can't really see that a valve guide is sticking but it is a possibility. Thanks for the help.
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