Guide Plate Install
Thread Starter
Burning Brakes
Joined: Dec 2003
Posts: 770
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From: Madison Mississippi
Guide Plate Install
I recently purchased a set of competition cam pro-magnum roller rockers 1.6 ratio (non-aligning) and purchased the guide plates and hardened push rods. I installed the guide plates under the studs and realized the rockers are raised up a bit. Do I need longer push rods to compensate for the height difference? Or, did I miss something? I ordered the standard size push rods and I think I goofed. Any suggestions at this point would be extremely helpful. :conehead
Drifting
Joined: Apr 2003
Posts: 1,292
Likes: 2
Re: Guide Plate Install (RUBYREDVETTECARD)
First put your engine @ TDC for N0. 1 cylinder (or any other, for that matter) on the compression stroke.
This sets the lifters on the base circle of the cam for that pot.
Next remove a rocker arm, clean up the top of the valve, and paint the tip with a felt tip pen.
Now replace the rocker arm and wiggle it sideways a bit to make a mark in your felt tip paint.
This will give you a line across the valve stem tip, where the roller has rubbed.
The line should be inboard of the centre of the valve stem. (maybe a third of the way from the centre to the edge)
If it is across the centre of the valve, or to the outside, the pushrod is too long.
Ideally use an adjustable rod to get the mark in the right place, but failing that, if it is a central mark, 0.10 inch shorter will be in the ball park.
Oh I forgot - it helps to remove the valve cover first! :D
This sets the lifters on the base circle of the cam for that pot.
Next remove a rocker arm, clean up the top of the valve, and paint the tip with a felt tip pen.
Now replace the rocker arm and wiggle it sideways a bit to make a mark in your felt tip paint.
This will give you a line across the valve stem tip, where the roller has rubbed.
The line should be inboard of the centre of the valve stem. (maybe a third of the way from the centre to the edge)
If it is across the centre of the valve, or to the outside, the pushrod is too long.
Ideally use an adjustable rod to get the mark in the right place, but failing that, if it is a central mark, 0.10 inch shorter will be in the ball park.
Oh I forgot - it helps to remove the valve cover first! :D
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Guide Plate Install (RUBYREDVETTECARD)
Britvette describes a way of checking the valve train geometry, which is a good idea, but probably not necessary, here. If you haven't changed the cam (different base circle) and the push rods are the same length, then you should be OK. The guide plates raised the studs by the thickness of the plates. BUT, the stud is threaded! The adjusting nut will end up further down on the stud to maintain the same position in relationship with the head and the rest of the valve train. The rockers have NOT been raised, only the studs. Unless you have done something very wrong, there is no height difference. You are over-thinking the situation and creating a "problem" mentially, that doesn't exist, in fact. Good luck, and...
RACE ON!!!
RACE ON!!!
Thread Starter
Burning Brakes
Joined: Dec 2003
Posts: 770
Likes: 0
From: Madison Mississippi
Re: Guide Plate Install (CFI-EFI)
You are the man!! thanks, I feel better now. I am adding the lt-4 hot cam and while I got the engine torn down I want to address all the bases carefully. I want to get back in the saddle and stay there for a while...Not back in the grease! Thanks for all the input guys! :hurray:
Drifting
Joined: Apr 2003
Posts: 1,292
Likes: 2
Re: Guide Plate Install (RUBYREDVETTECARD)
CFI-EFI makes a good point.
It was the 1.6 ratio that concerned me however, (is an LT-1 stock ratio 1.5, same as my L98?) Also I don't know if the hot cam has the same base circle as stock?
If the above are non-issues :iagree: with CFI-EFI, the guide plate should make no difference.
It was the 1.6 ratio that concerned me however, (is an LT-1 stock ratio 1.5, same as my L98?) Also I don't know if the hot cam has the same base circle as stock?
If the above are non-issues :iagree: with CFI-EFI, the guide plate should make no difference.
Drifting
Joined: Aug 2000
Posts: 1,521
Likes: 0
From: West Islip New York
Re: Guide Plate Install (RUBYREDVETTECARD)
They do make different rocker studs for those with guide plates and those without. They're real cheap -
I think if you use studs from a head not using guideplates on a head with guide plates installed you might not get enough depth on the stud when you screw it in.
You might want to take some measurements.
I think if you use studs from a head not using guideplates on a head with guide plates installed you might not get enough depth on the stud when you screw it in.
You might want to take some measurements.
Pro
Joined: Feb 2002
Posts: 533
Likes: 0
From: Augusta Ga
Re: Guide Plate Install (1MoorTym)
I just had my bosses milled for plates. I did that so I wouldn't have to worry about bottoming the rocker out and running out of adjustment. It's only an eighth inch, but it would have sucked if that would have kept it from getting on the road.
[Modified by BigC4, 9:06 AM 1/31/2004]
[Modified by BigC4, 9:06 AM 1/31/2004]
