Hitch

The rocker arm does not have a specified height as the only thing that determines the height is the pushrod and the valve stem. I'm confused as to how the guide plates being installed or not installed affects this relationship.

knight37128

If the stud is lower (no guide plate) then there is not enough thread on the stud to get it to the correct height.

It is essentially riding on the "top" of the stud not in the middle. On factory rocker arms, the stud pokes through the nut. Now think of a lower stud, it would not poke through. Thus you will have too much "flex".

I ran across this last summer. He put washers under the studs, no more bent push rods, or broke rocker arms.

You can buy shaft mount rocker arms or you can put the guide plate (washers will work) back on.

Hitch

This is like a tar baby..

If what you are saying is true how would you be able to adjust the valve properly?

63C2splitter

What type of push rods are you using? If the heads have stronger springs you may need to get thicker walled push rods(.080 or .090).

knight37128

If, as you say, it makes no difference. Why does General Motors offer two (2) different screw in studs for the small block Chevy?

One for guide plates and one for without guide plates.

Item number 8210 and item number 3973416.

http://www.competitionproducts.com/p...t_on=&sort_by=

Wow, maybe someone at GM has run across this before.

JohnZ

GM only sells one - the GM #3973416, with the hex on the base; the other one (#8210) is an aftermarket threaded stud with no collar or hex on the base, probably made by Pioneer or Federal-Mogul (the photo of #8210 is incorrect). The only thing that determines the position of the rocker arm, ball and nut is the length of the pushrod and the valve stem.

wombvette

John, you forgot all the s and the and

knight37128

Turn to page 163 in your GM Performance Catalog.

12495497
Screw-In Rocker Stud Kit (3/8")
These 3/8" studs fit all high-performance small-block V-8 and
90° V-6 Chevrolet cylinder heads machined for screw-in
studs and using guide plates. Unlike pressed studs, these
screw-in studs won’t pull out of their bosses under high
load. Kit includes 16 pieces. For single stud usage, use P/N
10168410. The lower thread section is 7/16".

12371058
Screw-In Rocker Stud Kit (LT1, LT4 style)
These 3/8" studs are used on all late-model LT1, LT4, and
any head not using a pushrod guide plate. Kit includes 16
pieces. For single stud usage, use P/N 12552126. The lower
thread section is 7/16".

wombvette

OK, lets quit arguing about things that didnt happen. So maybe you can get one with , or one without. In this case, it doesnt make any difference. This valve is galled and stuck in the guide.

Hitch

Wayne,

Excellent pics.. So it was the valve guides are expanding and causing the valves to stick? Or was this because the valve seats and were not machined properly and this caused the exhaust valves to heat up and cause the valve to stick in the guide? Dave

Realtor-Bob

Hi Guys,

You all have left me in the dust with all this stuff. It's beyond the comprehension of my pea brain. That's why I took it to Wayne.

Bob

larryseed

Don't feel alone>

Tom454

I just took apart a set of heads that were worked on by "The Man", and here is what I found...

Heads were cracked & re-welded.
Heads had damage repaired by JB weld.
Intake bolt threads in one head were "heli-coiled" using 3 different manufacturer inserts... 1 of them failed completely, 2 were on the verge.
Valve guides were knurled.
Valve seats were cut off center from the valve centerline.
Valve seats had cutter blade "chatter" marks all over them.
Valve seats were the wrong width (affects heat dissipation)
Valve seats are not centered on the valve face.. can cause valve head to warp due to improper heat dissipation.
Valves were at the wrong installed height.

When they gall that badly, it's usually a sign that the guides were too tight on the valve stem.


But since I do not have the heads in my hands, I do not have an opinion. I'm just an innocent bystander.

Injected Stingray

Bob this is a common problem when converting older heads to stainless steel valves. The original cast iron guides don't have the proper clearance they have to be opened up a little. My cylinder head guy won't even install stainless valves with out bronze guides because of gaulling. Have bronze guides put in before you hurt your bottom end. Chris

wombvette

I agree with this and that is the way we are proceeding. The material is definitely being deposited on the valve and causing the problem. Though, when we check the guide it measures just fine and you would never dream that it would gall. I am not going to blame my machine guy though. He inherited these crappy heads just like I did.

Hitch

Wayne was "The Man" SA? If so that is 2 for 2 as it relates to problems lately.. Dave

Pop Chevy

Either the guides are too tight or they are simply not getting enough lube. Valve stems DO need a little oil, not a lot but a little. What type of seals are on the heads?

Tom454

On the pair of heads I took apart... I don't believe Wayne was Da Man. I was told otherwise. Wayne is a smart guy. I met him when I was a member of the Raleigh Corvette Club.

I have respect for Wayne. I don't think he would knurl valve guides.

Hitch

Tom, I to have a great deal of respect for Wayne I was refering to SA of Fuquay who owns a Speed shop. The same place that built Rob's motor that had to have the heads pulled off it because they were junk. Dave

Tom454

So when are you coming over to play on my backhoe?... I know you miss it. Don't lie.