[Mean Green]

I bought a new engine with dyno time only on it.

I pulled it apart to change the cam and noticed the pushrods are rubbing against the guide plates/ head. In the pics, you can see the dark marks on the pushrods. I can feel a slight ridge in the pushrod with my finger nail where the dark marks are.

Do I just clearance the area, replace the pushrods, and check for interference?

I'm thinking of using a hand file (fine rat tail) and sand rolls to clearance the area. Is there a better way?

[mysticmissle]

that a 3/8'' push rod in a guide for 5/16''? check the pushrod hardness, it should not be harmed with a light file or knife contact, if it does, it may be part of the problem
that style rocker is going to have some side to side movement as designed.

[Mean Green]

I'm not sure about the guide plates. There is .026 clearance total between the pushrod and the guide plate. So .013 on each side of the pushrod.

The pushrods are 3/8. I was told they are Smith Bros pushrods. And a cheap China Swiss army type does nick the pushrods with moderate force.

I also have some Manley pushrods here for a different engine. The same knife with the same force, does not nick the Manley pushrods.

So the pushrods are most likely the problem?

[Stan Weiss]

From what you say the push rod maybe softer than it should be BUT they should not be making any contact.

Stan

PS - What ratio are the rocker arms?

[mysticmissle]

they are going to move around with a normal stud, NON SHAFT MOUNTED (BOLD FOR STAN), roller rocker arm. If there was no side movement why would you run a run a push rod guide?
I think you are on the right track with the pushrods. Maybe a bad batch or a parts selection from previous owner
what heads are those with offset rockers and no shafts?

[Stan Weiss]

Originally Posted by mysticmissle

they are going to move around with a normal stud, NON SHAFT MOUNTED (BOLD FOR STAN), roller rocker arm. If there was no side movement why would you run a run a push rod guide?
I think you are on the right track with the pushrods. Maybe a bad batch or a parts selection from previous owner
what heads are those with offset rockers and no shafts?

Looking at the picture that was posted either someone ground on the head and push rod guide plate or something is wrong with the clearance. I also would still like to know what the rocker arm ratio?

Looking at the picture I do not see contact from side movement.

Stan

[mysticmissle]

actaully those look like isky sbc guide plates, that may be part of the issue. the U in the guide plate may not be deep enought to your point. the hole in the head looks like its been clearanced for 1.65 or more ratio rockers but hard to say, not knowing the history.
but why did pontiac install millions of guide plates on heads if the rockers would have stayed straight the whole time without them?

[Skip Fix]

"actaully those look like isky sbc guide plates, that may be part of the issue. the U in the guide plate may not be deep enought to your point. "

I found that on their 2 piece 3/8 guideplates when I used 3/8 on my RAIV head.

[Stan Weiss]

Originally Posted by mysticmissle

actaully those look like isky sbc guide plates, that may be part of the issue. the U in the guide plate may not be deep enought to your point. the hole in the head looks like its been clearanced for 1.65 or more ratio rockers but hard to say, not knowing the history.
but why did pontiac install millions of guide plates on heads if the rockers would have stayed straight the whole time without them?

I can be wrong (will not be the first time) but I think that that ball / stamped stud rocker arms have more movement that the stud rollers do.

Stan

[Mean Green]

The rocker arms are Harland Sharp 1.65 ratio with .250 offset.

Isky lifters with .180 offset

The heads are KRE high ports.

It does look like the head and guide plate have been ground on for clearance.

[455-4+1]

I had the same issue, needed the Isky 2 piece guideplates due to an offset intake lifter, pushrod tube and rocker on an iron D port. 1.65 rocker and roller cam and 3/8" pushrod hit the back of the U in the guide plate slightly. Just ground out the rear of the U slightly (engine assembled with new heads and valve train days before a UIM World series event). Ran flawlessly so never bothered to change things out.

[Mean Green]

They are Isky 2 piece guide plates that have been tacked together.

[Mean Green]

Better picture attached.

[mysticmissle]

you can see in the head where the push rod has been rubbing. theres is couple schools of thought there.
if it was mine, i think i would clearance the guide plate a little more and swap out the pushrods and inspect it in a short time period. Is it only the intakes?
if so is your cam a liitle bigger on the intake side?

[Stan Weiss]

If this were mine what I would do is put some machinist dye on the push rods and turn the engine over by hand to see where they make contact.

Stan

[Mean Green]

Mystic Missile, I will do just as you suggest. And yes, it is just the intake pushrods and the cam has .015 more lift on the intake.

Stan, will do.

Thanks everyone for all the help. I really appreciate it.

[Dragncar]

Originally Posted by Mean Green

Better picture attached.

Hole in guide plate does not look like it is centered exactly over pushrod hole.
So, most likely the previous owner/builder tacked them in the wrong spot.
The 2 piece guide plates and human error are the variable here.

[Skip Fix]

That first shot with the rocker plate looks off from hole and pushrod. Looks like hits guide on one side aluminum head hole on the other.

[taff2]

The pushrods have to touch the guide plates-otherwise they are not being 'guided'. . The pushrods must be hard enough so that the light rubbing doesn't wear them. And smoothing off all the sharp corners on the guide plates will help .

[steve25]

Those guide plates where ground, but never polished out to remove the sharp edged left from the grinding on the top and or bottom side.