Hughes rocker arm pedestal shims

-
S

Shadow

Well-Known Member
Joined
Mar 11, 2013
Messages
117
Reaction score
13
Location
Porterville ca
Anyone have experience running these
shims? Ordered some and have them on
the way but wonder if there is any nightmare
stories associated with them. Going into
340, stock cam, stock compression,
x heads, 273 rockers with the cup and ball
pushrods. Will probably never see 4000 rpm
just a street car.
 
Why would you need the shims with adjustable rockers?
 
On my new Eddy heads with Hughes rockers I needed one fat shim under the shaft to get the geometry right. No big deal and the soft shims may help seal the oil from the heads to the shaft (or make it leak more, who knows?).
 
airwoofer said:
On my new Eddy heads with Hughes rockers I needed one fat shim under the shaft to get the geometry right. No big deal and the soft shims may help seal the oil from the heads to the shaft (or make it leak more, who knows?).
Click to expand...
:cheers: just went thru this on my victor knock offs. you may or may not need them, depends on your stuff, in my case I put .060 in,ended up pulling them all back out. the valve contact area came out perfect w/o them at all on the procomp heads. that being said,to you guys that question this procedure,: the valve train geometry dictates if, and how many shims are needed to get full cam lift. there is a sweet spot (if you will) that will get perfect or close to perfect valve -roller contact and "have full cam lift." making up the diff. w/ the adjusters ain`t the right way to do it. if done that way the geometry may or may not be off. usually it`s not perfect. read hughs engines tech articles on this, they are better w/ words than I am, it`s very informative, and after going thru this, I agree w/ them. never done a small block, but they are supposed to be more criticle than the big blocks. just ordered the correct pushrods for mine this morning. ' They are alittle differant than can be bought from anyone not custom building them. mine were 9.480 long w/ everything centered. sorry for the long post guys!!!!!!!!!!!bob:glasses7:
 
famous bob said:
:cheers: just went thru this on my victor knock offs. you may or may not need them, depends on your stuff, in my case I put .060 in,ended up pulling them all back out. the valve contact area came out perfect w/o them at all on the procomp heads. that being said,to you guys that question this procedure,: the valve train geometry dictates if, and how many shims are needed to get full cam lift. there is a sweet spot (if you will) that will get perfect or close to perfect valve -roller contact and "have full cam lift." making up the diff. w/ the adjusters ain`t the right way to do it. if done that way the geometry may or may not be off. usually it`s not perfect. read hughs engines tech articles on this, they are better w/ words than I am, it`s very informative, and after going thru this, I agree w/ them. never done a small block, but they are supposed to be more criticle than the big blocks. just ordered the correct pushrods for mine this morning. ' They are alittle differant than can be bought from anyone not custom building them. mine were 9.480 long w/ everything centered. sorry for the long post guys!!!!!!!!!!!bob:glasses7:
Click to expand...
by the way, the more I get into these procomp heads, the better I like them--just sayin--bob
 
The heads were just milled a bit and when
I tried to adjust the valves I could not get the
adjusters short enough, they got where the
cup on the pushrod was hitting the rocker so it
seemed to me the easiest just to shim it up
a bit rather than to chase down shorter
pushrods and it looked like it would also keep the best geometry.
 
Your real fix is getting the right length pushrods. Smith Bro's makes some great ones. Not cheap, but light-years better than the stock stuff and they'll make them any length you want. I have two sets, one in my 340 and another in the 318 I'm building. The 340 has Harlands, the 318 will be getting stock style 273 rockers.

Shimming up the rocker shafts should work as well, and that will cost a ton less. The shims shouldn't cause you any issues.

But why on earth will your 340 never see more than 4k rpm? Even a bone stock 340 has a lot of fun left in it at 4k. :burnout:
 
Shadow said:
The heads were just milled a bit and when
I tried to adjust the valves I could not get the
adjusters short enough, they got where the
cup on the pushrod was hitting the rocker so it
seemed to me the easiest just to shim it up
a bit rather than to chase down shorter
pushrods and it looked like it would also keep the best geometry.
Click to expand...

If you're having trouble getting the adjusters set correctly, the heads were milled much more than a "bit". I agree. Correct length pushrods are the right way to do it. I cannot imagine how much in the way of shims you'll need.
 
If the pushrods are too long due to milling you need to buy shorter pushrods.
On a Mopar (or any shaft system) if you put shims under the shaft, you affect the geometry of the rocker and the valve stem tip in a negative way. That's because the centerline of the valve stem is tilted towards the shaft. If you drew a line up from the valve and up through the center of the shaft (like straight up through a hold down bolt), those lines would eventually intersect. So as you raise the shaft you also push it sideways a little. The rocker tip moves towards the exhaust side of the valve's tip. That's a bad thing for power, longevity, and guide life and it doesn't take more than .010-.020" of shim to cause problems.
 
Shims under the rocker shaft are to get the rocker pad centered on the valve stem. Getting the correct length pushrod solves the adjuster stud problem. Spend the time to get the rocker centered on the valve stem. Put some grease on the valve stem and crank the engine. The mark on the valve should be centered. The shims will change it. You can buy .030 sheet aluminum at the hardware store. Cut it to size , put them under the shaft and let the fun begin. It's a pain but well worth it. Incorrect rocker geometry will cause all kinds of problems. Buy an adjustable pushrod to get the correct length and have Smith Bros. make you some .085 wall 5/16 rods. Remember a shortcut is the fastest way to somewhere you didn't want to go.
 
I guess I'm looking at it the wrong way. Already as much as I've backed the adjuster out of the rocker I'm hitting the rocker with the cup of the pushrod and the angle that the rocker sits at now is rocked way over on the pushrod side, if I get a shorter pushrod my rocker arm will end up rocked even deeper into the pushrod side which is definitely not the geometry she came with from the factory, so I thought the shims might keep the "teeter totter" more centered. Make any sence at all ?
 
I've actually also wondered if the machine shop knew they were going to mill the heads if they should have accounted for the difference with the installed height of the valve stems themselves. If they were to be surfaced a bit too it seems like things would be way more in line but to mill the heads but leave the valves at stock length already throws things off right from the start.
 
Shadow said:
I've actually also wondered if the machine shop knew they were going to mill the heads if they should have accounted for the difference with the installed height of the valve stems themselves. If they were to be surfaced a bit too it seems like things would be way more in line but to mill the heads but leave the valves at stock length already throws things off right from the start.
Click to expand...

if, your valves were set up right to start w/, your answer is pushrod length. might be worth checking to see if they were (are) right. sha:banghead:ving the heads shouldn`t change they valve set up , but it will and move your rocker arms closer to the cam!
 
Shadow said:
I've actually also wondered if the machine shop knew they were going to mill the heads if they should have accounted for the difference with the installed height of the valve stems themselves. If they were to be surfaced a bit too it seems like things would be way more in line but to mill the heads but leave the valves at stock length already throws things off right from the start.
Click to expand...

Milling the gasket surface has nothing to do with the stem length or valve job.
These are what can affect geometry on a Mopar shaft system:
-The stem heights are a result of the valve job: the seat depth, the seat cut on the valve, and the stem cut of the valve. Those are all set during the valve job.
-The rocker shaft centerline position is set by the factory and unless you replace the stands with support blocks, it never changes.
-The rocker's tip position may vary depending on the rocker manufacturer.

What I would suggest is you get a pushrod checker. Thread the adjuster down so there's 1/2 a thread showing and then use the checker to determine the length you need (and don't forget the proper lifter preload if it's a hydraulic tappet). Then call Manton or Smith Bros. and have a set made and delivered to you.
Pushrod length is one of the innocent bystanders of head milling to gain compression. If you go too far (and again - that's from the factory original surface... not the surface you may have on your heads if they were cut once eons ago) then you have to start buying parts to get things to work right.
 
I see your point there, no matter if the heads were milled or not the valve stem height in relation to the pedistal would not change. I think a guy actually needs a little on both sides. My adjustable rockers can give me a shorter length ( than stock) on the pushrod side simply by backing them off but I feel as though I need to retrieve the correct geometry with also a slight raise of the pedestal. Need to get the grease out like Ted said, mock them up and see where it's at.
 
Yup. If you don't want to use grease a sharpie or dykem works too.
 
You must log in or register to reply here.
-

Back
Top