Roller Tip not centered on valve stem
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Roller Tip not centered on valve stem
I'm rebuilding a 65 289 (my first!) with 351W heads and the sportsman roller tip rockers I installed are not centered, side to side, on the valve stem. They look dead center front to back but I'm concerned that they might slide off the side of the stem. They are stud mounted and I'm using guide plates as well. Should I be concerned or will they center up them selves once I get it running?
Cargo Master
Joined: Dec 2004
Posts: 2,232
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From: NE Texas
What are you calling front to back? Do you meand front to back relative to the vehicle or relative to the rocker arm?
When you check push rod length, you should see a line across the valve stem that goes in the same direction as the vehicle and should be centered on the valve stem side to side with respect to the vehicle.
When you check push rod length, you should see a line across the valve stem that goes in the same direction as the vehicle and should be centered on the valve stem side to side with respect to the vehicle.
Posting Guru
Joined: Mar 2010
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From: northern va
1970 heads for a car. not bad heads did you port them? and check are the distance between each stud to see if they are the same w/ a micrometer (i cant think of any other way to check) are all off center the same or only some?
Postmaster
Joined: Mar 2005
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From: Earth
Is there side-to-side play in the rocker? It's held in alignment by the guide plate, so if there's play you may have the wrong gp/pushrod combo.
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I hit them with a micrometer and all stud to stud (intake to exhaust) spacing is the same, as well as valve stem spacing. I mean should the stem be directly in the center of the roller? None of the stems are "outside" of the roller, just some are dead center and some aren't. The po had the heads ported and polished but he got rid of his project before ever installing them, that's all I know about them. When I got the block machined I had the shop take a look at the heads and was told that they were excellent.
There's a minimal side to side play with the valve fully closed, more of a pivot/rock around the pivot ball in the center of the rocker arm than a side play.
This is my first rebuild so hopefully you guys can set me straight...
There's a minimal side to side play with the valve fully closed, more of a pivot/rock around the pivot ball in the center of the rocker arm than a side play.
This is my first rebuild so hopefully you guys can set me straight...
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FTE Legend
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From: Ottawa, Ontario
There was a hugh thread on this very subject over on the Corral forum and the final call made by some very experienced engine builders and backed up by engineers was that NO.. the rocker tip doesn't have to be perfectly centered in the valve stem. It should be towards the center obviously to minimize side loading of the valve stem but the main thing is to set them up so the movement pattern is as narrow as possible. And to do this right with stud mounts is a bit tricky, you have to set the rocker height so that it is perpendicular to the valve stem at exactly half travel, doing so will ensure the rocker tip moves an even amount in and out on the valve stem as it travels from fully closed to fully open. This will also produce the narrowest contact pattern on the valve stem.
Postmaster
Joined: Jun 2005
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Make sure you are using the right size pushrod, guide plate and stud. 7/16 rockers on 3/8 studs, or 3/8 guide plate with 5/16 pushrods will make for problems. sounds like you might have 3/8 studs with 7/16 rockers.
Need pics..
Need pics..
Senior User
Joined: Feb 2006
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From: cleveland,Oh.
The alignment of the guide plates will cause problems too,by alignment I mean are the push rods straight side to side,which would be front to back if the engine is in the car truck or on a stand. The push rods should have almost equal distance on either side of the slot with the push rod installed.
You dont want the push rods contacting the guide plates. Its a tedious job, pay attention to the details, and make you're first build a sucessful one!
You dont want the push rods contacting the guide plates. Its a tedious job, pay attention to the details, and make you're first build a sucessful one!
Postmaster
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The alignment of the guide plates will cause problems too,by alignment I mean are the push rods straight side to side,which would be front to back if the engine is in the car truck or on a stand. The push rods should have almost equal distance on either side of the slot with the push rod installed.
You dont want the push rods contacting the guide plates. Its a tedious job, pay attention to the details, and make you're first build a sucessful one!
You dont want the push rods contacting the guide plates. Its a tedious job, pay attention to the details, and make you're first build a sucessful one!
the push rods rub on the guide plates all the time, they are what keep the roller on the valve tip.
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New User
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Pushrods are centered in all guide plate slots and they are straight. After all of the advice and reading on this and the corral, I'm going to press on with what I've got. I'll let you guys know how it goes. Mahalo for all the info.
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