Got a slightly bent pushrod.I guess thars what sheared off my rocker arm stud.Spring looks fine and lifter looks good best i can tell.Ive got a rev limiter so why/how`d this happen?Just a bad stud or what?What do I need to do or look for besides replacing the stud and pushrod.This started as what I thought was an injector or tune up problem so my original post is on the tpi board heres a try at a link.https://www.thirdgen.org/tpi/injector problem/

 

look closely at that valve spring. I bet its broken in two.

 

I`m no mechanic so i double checked it,but unless there is an invisible crack in it its fine.I ran my fingers around it and felt no cracks or burs either.My springs are supposed to be good up to .525 lift,i didnt over rev,so could the lifter be bad.The moter has less than 4000 miles on it but ive hear they could be bad even on new crate moters sometimes.I`ve heard about lifters pumping up or something and breaking studs or bending rods.?????????

 

sounds like your spring was binding..

 

what would cause that and why

 

If the head wasnt set up properly for the lift of the cam, the spring will not have enough clearance. As the cam lift exceeds the physical limitations of the spring/head setup, the spring will bind. This can bend a pushrod. Something bent the pushrod,they usually dont just bend for no reason.

 

More likely whatever bent your pushrod also broke your stud.

 

We took the heads to a machine shop and had something done .I think heli-coiled or something.What should be done to them.Check my sig,the cam is under .500 lift and my springs were designed for the cam,came on the heads and are supposed to be good to .525 lift.I didnt think there would be a problem.The guy who built it said he checked for coil bind and valve lash.

 

wait you brought your heads to a guy to have them done and he checked for valve lash? without the block? he is a magician

 

No.i took them to a machine shop.Then when another guy,put the engine together and installed the ENTIRE engine,He did all that.I trust his work.He has been working on all my cars for the last 4 years,has been building race moters for 30 years and is ASE certified.I witnessed him build a 440 hp 306 C.I. he put in his nephews mustang and it still runs like a champ.Magician....no,damn good mechanic........I believe so.Also,I didnt brought or bring them anywhere.I took them to a machine shop

 

That's only one part of the numbers. You could put springs in that are good for up to .600" lift and still have problems if the heads and the rest of the valve train isn't set up properly for them.

Piston to valve clearance needs to be checked to see if the pistons will accept that much lift. The top of the valve guides need to be machined down to accept a higher lift. If the lift is too great, the bottom of the spring retainer will hit the top of the guide. The rockers need to be able to move the full rotation without hitting the rocker stud. A full roller rocker has no problems but a stamped steel type rocker needs to be a long slot rocker for just about anything over .500 lift. At maximum lift, there should be a minimum of .060" between the spring coils. Any kind of interference like these will bend a pushrod.

 

OK.I`m gonna talk to my mechanic about this,but I cant imagine him missing it on my engine and not on others he`s done.So on an l-98 block with l-98 alluminum heads with a stock GM cam do you think I would still need to worry about that?And i do have full roller rockers if that matters.thanks for the replies.I`M not trying to say any of yall are wrong I was just under the impression from the guys at GMPP that all this stuff would work together fine considering its a pretty miled combo with mostly stock production parts.Just wondering WTF,I hate not being able to drive my car with the tops off on a beautiful day off of work.

 

do yall think i may have damaged the valve?Should I just replace the stud and pushrod and see what happens or what?

 

My builder was recommended to me by a Professional Straight Line Race Driver, but because I do not want be liable I won't mention any names.
So why would a professional like that forget to make sure that the oil dip stick hole wasn't blocked by the oil pan gasket, know not to use a generic oil filter he knew had problems, forget to replace the stock short rocker studs for the longer made for roller rocker studs?
I'm not saying that anyone is perfect, but all of these problems were preventable. If I make a mistake well, you all know how that story ends, but I'll be dammed if I going pay someone else to make mistakes. Because of that I always make sure that anyone who does any work for me garantees his workmanship.

The moral of the story is never take anything for granted, check, recheck, then check again until you're statisfied.

 

so should I just put a new rocker stud and pushrod on and see where I stand.DId I possibly damage the valve.I guess I`LL know if it runs like crap when i re place the messed up stuff.

 

Do a leakdown test on that cylinder. If a valve is bent, it will leak.

A compression test will mean installing the rockers and cranking the engine over.

 

well i replaced the pushrod and rocker stud and polly lock.Car runs fine and seems ok.I think the valve could stand to be adjusted by a pro.It loosened up on me about 3 times after short drives and this last time i guess i got it.Drove it about 30 minutes and all seems fineI have never adjusted the valves my self.I did it by reading some instructions but i think I`ll still take it to a mechanic for a check up.

 

From reading your sig, you are asking .512 lift from spring rated to .525, does anybody else think that is a little close (guessing your cam is a 476/480 with 1.5 rockers)?

 

No. Its .476/.480 with the 1.6`s.pace performance part number 12551142.I also thought I`ve seen a guy or two running the LT-4 hot cam with these same springs.I`m not saying it`s a good Idea but I`ve spoken to one and he said he has had no problems.I think his screan name is brisk.My car is still running slightly roughat idle but cleans up under a little load.Could the timing have gotten off some how or should i adjust all the valves?

 

Found my rough idle.Breather grommet was torn and caused a vacume leak.Next problem.Changed my oil and had some metal shavings.I`m hopeing its just particles from the broken stud.What do yall think.Last thing.Turns out my pushrod wasnt slightily bent.Must have been the counter top I was useing,cause a friend of mine told me to roll it across a sheet of glass.I did and it was fine which leads me to believe either the stud was loose or to tight because the geometry looks good.The roller tip operates right over the center of the valve stems.Atleast it`s good to know the pushrod was fine meaning lifter and all should be fine too.....I hope.

 

hmm, rocker keeps backing off, and metal shavings in oil pan. What kind of cam are we talking about here?

 

Well,The rocker is fine now once I got it set properly.but it seems another one on the other side(either 2 or 6) just started tapping a little.Seems every couple of months i gotta re adjust one.Guess i`m gonna go the stud girdle route.As for the cam its a GM production cam,LT4,WITH 1.6 rockers. and the supporting mods are in my sig.I`m hopeing the metal shaveings are from the stud that broke and sheared off inside the polly lock.The car seems to be running fine with all its power.So I am going to do a compression test and make sure evrythings ok.It seems to be running slightly rich until it gets up to opperating temp and the oder seems to go away a little.