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It is indeed a wear problem. These heads do not come with 3/8" guides because *they are NOT out of the box Edelbrock heads*. These were CNC ported, guides installed, and valves supplied by Craft Racing. |
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Brent knows what he speaks about: I have 11/32 guides not factory 3/8. |
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Thanks, OliveR |
Call Lance at Craft Racing and ask for some guides.
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If you have a web site / phone number / email address for me please ?? Thanks, OliveR |
Lance at Craft Racing is taking off where Keith Craft left. They still do the same CNC ported Edelbrock heads and will have parts on the shelf.
https://www.craftperformanceengines.com/ |
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Poor sentence structure on my part, Brent. I was agreeing with what you said, and then observing (my opinion, not yours) that an 11/32" stem in a ⅜" guide could produce a significant wobbling of the valve in the guide — similar to what he was experiencing. Ed |
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If it was me, I'd replace the valves too.
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Or why not hone for a K-line guide insert to bring back 11/32, and run a tight clearance, since they claim to have better life.
I am still dubious about the Edelbrock guides. |
Keith Craft seemed to do a fair amount of international sales when they built my engine so unless they have changed under Lance, it should not be a stretch for them to get parts to you.
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Well I've done a partial test which should required a full engine reassembly but here is what I did:
I've resinstalled rockers assembly on one of my head without valve springs. As there is a "line" on each valve showing where valve stop when full opening I make pictures of rocker when valve is closed and when valve is open (stopping rocker when "line" on valve reachs the top of the valve seal). OK this test should be done with head installed on block, pushrods, etc... BUT does my test doesn't show a rocker pivot issue / pushrod lenght issue ? which could have caused my valve wear premature failure ? |
valve full lift
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A rocker, roller or otherwise, will not remain centered on the valve stem. The reason is the roller or (rocker wear pad) traces out an arc that is determined by the distance from the center of the roller to the center of the pivot on the rocker shaft.
If you use the valve lift to establish the length of a chord describing the valve motion in the guide you can position the rocker to center the motion of the roller across the middle of the valve stem, favor the portion of the valve stem closest to the exhaust side of the head or favor the portion of the valve stem closest to the intake side of the head. My personal preference, when building pushrod engines, is to center the motion of the roller across the middle of the valve stem. When you go to either of the exhaust or intake positioning models you place unnecessary side loading on the valve stem and the guide, resulting in premature wear of the guide. Ed |
The roller should start from the rocker shaft side of valve stem centre, roll ACROSS centre at half lift, then be at back to the start point at full lift.
Yours appears to start at centre, and by full lift is coming to far away from centre at full lift. So your valve stem height needs to be increased, longer valves, a lash cap, or lower the rockers. Lash cap is by far the easiest way. Your roller moves too far, especially since this happens at the highest load at max valve lift. Gary |
It’s because on the “full lift” picture he has “input” way more lift than what he has. He is trying to go to whatever mark that is on the valve and that’s not accurate. When the valve lock groove is almost touching the valve seal, that should be an indicator that somethings not right with the experiment. If you try to open the valve an inch, you’re gonna see something like that.
There is nothing wrong at all with that first picture. T&D rockers are some of the easiest to set up and I’m probably the most anal about setting up valvetrain geometry. In addition, pushrod length has nothing to do at all with geometry on a shaft mounted rocker. |
I was thinking that looks like a lot of camshaft lift.
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what caused those marks on the valve stem just below the keeper lock grove??
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