to replace or not replace .......that is the question!

[olileo]

i need a second opinion.
i have a chevy 350 on a 69 c10 with notched rocker studs(2). the rocker arms have been readjusted and slack removed, but i continue to have tapping noises comming from that head. my mechanic has "advised" me not to worry about it as a way to save me some money.which i aprreciate. the worst, he said ,that can happen is if the stud snaps off it will only be firing on 7 instead of 8. i plan to replace the studs or heads(whichever will be cheaper)down the road some time.in the meantime it will be a short trip errand runner. nothing more.should i worry bout it now or can it wait?

[silicon212]

Well. if a stud comes out, there will be more than simply a dropped cylinder. You could wind up with a bent pushrod and a damaged camshaft. If the lifter comes out of its bore, you can have an oil pressure failure, leading to engine failure.

If the stud is pulling out of the head, you can anchor it with a pin drilled into it through the head.

[luxeryvic]

i say replace the heads, you can get a used pair for relatively cheap and by the time you pay for labour itll probly be cheaper to get heads and change them yourself IMO

[777stickman]

I built a 327 for a friend to put in his '34 Chevy glass body coupe. That was 7 years ago. Per his request the cam and lifters were Crane. The push rods were Summit as were the stock style rockers. Early this year the motor developed a lifter tick and a loss of power.

Here's what we found.

The upper end of the #3 intake push rod and the push rod side of the rocker were toast. The snap ring that holds the lifter together was gone??

What caused this??

Replaced the lifter, rocker arm and push rod and all is good.

Hope this helps..............Steve

[rhandwor]

It could have been a bad lifter but I think the valve guide is worn allowing the push rod to move sideways. Normally you can put your hand on the rocker arm and feel the slop. If this is the problem you can put a new valve guide in it but I would have a machine shop do a valve job and replace defective guides.
If you watched when you set the valves normally it is apparent and you get it set and it changes position. I doubt this happened quickly but over some time.
Seven years it is his cost to pay you labor for your work.

[MrPbody]

Valve guide is a good bet. Chevy engines are notorious for this, especially the older small blocks. If you adjust it and it quiets down, but the clatter returns quickly, that's it.

Replacing studs isn't as straight-forward as you might think. If the notch is too deep, it CAN break the stud easily. If that happens, the head will have to come off to repair it. "Repair" studs are available, that have a 7/16-14 thread on the bottom, with no "hex" (like the typical screw-in stud). The tough part is tapping the hole straight. We do it here in the shop, on a precision machine. Can't do that "in the car".

If you do remove the heads to replace the studs, I would simply have ALL the studs replaced and install guideplates at the same time. Cheap "insurance". If you DO install guideplates, the pushrods MUST be replaced with "hardened" ones. Not expensive, but VERY necessary.

Jim

[rhandwor]

What supplier are you using for repair studs. Do they have any for exhaust manifold studs. They would be a handy item. Have you ever seen a small hole saw for removing broken exhaust studs in aluminium heads?