89RsPower!

So the other day I was driving home from work around 40 mph or so when out of no where my car starts to backfire and run like crap. My first thought was that one of the cheap roller tipped rockers I used must have come apart at the tip and lost the roller. So after Idling the last half mile home I began to listen to which bank the noise was coming from, due to my usual luck it was the passanger side bank (TPI car with complete factory emissions/A.I.R setup and heater hoses/diverter covering the valve cover) After taking all of the junk out of the way to get enough room to take the valve cover off I was surprised at what I found. The el cheapo roller tipped rocker was just fine, turned out the sturdy "looking" scew in stud snapped in half like a twig after around 30k miles of reliable service. Has anyone ever had this happen before? Are the studs that come with these heads junk? I built this car for my father as a daily driver so I know for a fact that it's not driven hard or beaten on, he simply drives he back and forth a few miles a day to work. Any way where can I buy a replacement stud? Need to get it back togather asap, any info would be appreciated.

sofakingdom

iTrader: (1)

http://www.lmgtfy.com/?q=world+castings+components

89RsPower!

thanks for the reply, sadly the only list valves and valve springs..

tuneupman

iTrader: (1)

i had one break on my word product heads at 5500 rpm. it made a funny noise. they are just a screw in stud for a chevy head. i got a used one from a local engine builder and all was well

89RsPower!

Anyone happen to know the specifics such as the base thread size, rocker nut thread size and overall length? Trying to order online which makes it difficult to compare simply by looking.

tuneupman

iTrader: (1)

i think i still have a used one at work . i will look for it today and get back to you

ASE doc

Get World Products techline's phone number from the website and call them. They would like to know that their rocker studs are breaking. Of course, double check valvetrain geometry to be sure there isn't a bind putting excessive strain on the studs.

89RsPower!

Well I stopped simply looking for an answer and decided to just measure it... Looks to be a 7/16 base with a 3/8 thread, Im assuming that "effective stud length" is the length of the stud from the top of the nut portion of the stud to the top of the stud, assuming that's right I believe these would be correct http://www.summitracing.com/parts/ARP-134-7121/

89RsPower!

I'm confident that the valve train geometry is correct with the current setup, I got the engine used with no idea of the actual mileage since it was rebuilt, so I really have no idea how old the components are. It had a flat tappet cam installed but stock length pushrods that I know for a fact were too long due to the amount of machining done to the block. While going through the engine I swapped in a used lt1 roller cam I had around with the factory roller components from the origional 305, the factory pushrods were too long so I replaced them with custom length pushrods along with a new double roller timing set. I didn't inspect the rocker studs at the time but it's possible that one was already slightly cracked from improper geometry from the flat tappet setup that was in it... Still I will recheck before I put it back togather.

ASE doc

Yeah. A good rule of thumb is .020 minimum clearance between max lift and spring bind. You're running roller rockers which is good so we know there's no bind in the fulcrums. Obviously there's no piston to valve clearance issues since you've been running the engine.

To double check piston to valve overlap clearance, install a soft spring like you can buy at the hardware store. It needs to be just stiff enough to hold the valve closed with the retainer and locks in place. Put the crank at 0 degrees TDC on the intake stroke(at the end of the exhaust stroke) and measure how far the valve can open in this state. Should be no less than .100. Turn the crank back and forth 10 degrees each way and check to be sure that there is no less than .100 clearance at any point.

tuneupman

iTrader: (1)

i was able to find a used one in my box and measure it and your numbers look good. that should be the part you need.

89RsPower!

thanks for the replies, will find out soon enough