Keith Craft Inc.- We service what we sell!!! Check out our Cobra engines!!! We build high performance racing engines and components for the fast pace strip racing industry as well as daily drivers who want to be FIRST!!!
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 ?
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
__________________
Help them do what they would have done if they had known what they could do.
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.
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.
Reports of valves fish scaling have been on the FE and Mustang forums
Get a child’s science kit microscope an look at your valve stems
I just used one to check the rings on this 390, they look beautiful reusing them
It’s a handy tool to have
The valve is off center because of the worn guide. Those marks look like where the plating or the case hardening has been worn off by the keepers. That should not happen. Counterfeit part? Hardening or plating prob?
A spring removal and valve inspection at 500, 1500, 3000, 5000 miles would be a good idea on the fresh motor. Pack nylon rope into TDC cylinder, couple hours
These motors were engineered with the valves lubed by lead in the fuel. USA fuel has friction modifiers in it to replace the lead somewhat, probably not allowed in EU fuel. Add Hapco lead substitute, a $50 gallon treats 200 gal gas
A Howard Cams 93360 11/32- .530 type seal with a band instead of spring would form a hydrodynamic seal allowing oiling where a spring seal will wipe off oil and stop oiling
I’m using the no band 3/8” - .530” 93320 Howard Ultimate seal, the 11/32” 93311 has .500 guide, these seals oil the valves too.
This didn't all happen just over night----It was maybe lack of compatible lubricants/fuel issues?????? To be so bad pretty much on all cylinders---wrong choice of oil to go with fuels from that area???????excellant choice of seals restricted amount of lube to valve guides which then wore enough to kill the seals which then let in huge amounts of oil sucked thru the intake guides???????
That cam is 248/248 @ .050", with a .638" gross valve lift. You will lose .015-.020" lift to valvetrain deflection, so at 100% optimal, you're at .638" lift. In actuality, you were probably getting about .615" lift at the valve.
Hard to tell anything from a side video, but it looks like the rocker starts on the intake side of the valve stem and rolls through. If you're opening the valve more than .600-.650", then you're going to get an exaggerated view.
I don't know what you'll see now as far as geometry with a valve/valve guide worn that bad, but the T&D rockers notoriously set up perfectly on an Edelbrock head with a standard length FE valve. In your video, I can see the valve moving back and forth in the guide. That will skew the results of a geometry check. If you have .030-.040" of wear, that would mean that the valve can move side to side in the guide by at least .015", which can affect the geometry quite a bit.
I would be looking at the amount of wear that you see on the stem. If there's more wear there than .600" lift worth, then that narrows the issue down to a surface finish/plating issue.
That cam is 248/248 @ .050", with a .638" gross valve lift. You will lose .015-.020" lift to valvetrain deflection, so at 100% optimal, you're at .638" lift. In actuality, you were probably getting about .615" lift at the valve.
Hard to tell anything from a side video, but it looks like the rocker starts on the intake side of the valve stem and rolls through. If you're opening the valve more than .600-.650", then you're going to get an exaggerated view.
I don't know what you'll see now as far as geometry with a valve/valve guide worn that bad, but the T&D rockers notoriously set up perfectly on an Edelbrock head with a standard length FE valve. In your video, I can see the valve moving back and forth in the guide. That will skew the results of a geometry check. If you have .030-.040" of wear, that would mean that the valve can move side to side in the guide by at least .015", which can affect the geometry quite a bit.
I would be looking at the amount of wear that you see on the stem. If there's more wear there than .600" lift worth, then that narrows the issue down to a surface finish/plating issue.
OK Brent so first of all I'm going to replace the guides and once done check the rockers/pivots.
Problem: Craftperformanceengines doesn't reply to my emails !!!! How can I order the new guides ???
A bit hard to tell until you get the valve guides replaced, and the valves reseated.
The roller should start on the side CLOSEST to the rocker shaft, sweep over centre, then be on the side OPPOSITE of the rocker shaft AT HALF VALVE LIFT, then sweep over centre near full lift. The pattern should be near centred over the valve stem, the narrower the better.
Your rocker does not have that pattern at all.
Put some engineers blue on the valve stem and watch the pattern the roller leaves.
A bit hard to tell until you get the valve guides replaced, and the valves reseated.
The roller should start on the side CLOSEST to the rocker shaft, sweep over centre, then be on the side OPPOSITE of the rocker shaft AT HALF VALVE LIFT, then sweep over centre near full lift. The pattern should be near centred over the valve stem, the narrower the better.
Your rocker does not have that pattern at all.
Put some engineers blue on the valve stem and watch the pattern the roller leaves.
Gary, as Brent said my guides are too worn to check rockers travel/pivot so I'm going to replace guides and check once done.
Could it be possible the engine in question was running extremely rich for its entire life and that's what caused the accelerated wear? This is more of a question than a conclusion, although I think it's possible.
Could it be possible the engine in question was running extremely rich for its entire life and that's what caused the accelerated wear? This is more of a question than a conclusion, although I think it's possible.
Guide wear like the owner has, is not caused by excessively rich A/F ratio.
Even it somehow ran continuously at 6:1 (typical cold cranking fuel requirements).
5Likes
Hybrid Mode
