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Discussion Starter #1
Evening All,
Here's an issue... I'm getting cupping/dishing on the ends of my valve stems on my 72 T120.
I'm running a big bore kit soooo 750cc, & megacycle 510-05 cams wich call for 0.010" valve lash clearance.
This problem just started, I've never had an issue before... & it is only cupping (1) exhaust valve (primary side) & (1) intake valve (timing side)...
I assume I'm getting good oil flow to the rockers considering the other two valves are fine, but I'll double check.
I'm also using all Kibblewhite components, springs, cups, keepers...black diamond valves etc.
Any advice....:confused:
 

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if you are you using the 5/16" Triumph valves you can get lash caps from a Ford dealer parts dept. they are $10 each but the will save the tops of the valves, then use a high zink oil like Vavoline VR1 50 wt.
 

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I had a similar problem on one of my valves which would crater and mushroom before any of the others ,so i ran lash caps,and i came to the conclusion that it was a valve tip/rocker geometry problem as the seat on this valve had sunk in a long way .
I have ended up getting new seats fitted to bring valve heads back to correct height and hopefully a better rocker angle
 

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i like the Ford valve cap idea; thing is all UK parts dept's will only run on part No's or at best which year and model.

Any ideas?

Thanks
 

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i like the Ford valve cap idea; thing is all UK parts dept's will only run on part No's or at best which year and model.

Any ideas?

Thanks
maybe there is someone out there that works at a Ford dealership that can look it up, all I ever did was ask for 5/16" valve stem caps.
We use them on bikes with heavy valve springs and big cams, it seams the valves take a real beating without them.
 

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Discussion Starter #9
Well, I'm already using Valvoline VR-1 50W, & I have some new mushroom type adjusters for the rocker arms coming in... I'm gonna use some high grade valve lash caps too...why not?
That & a fresh head job....we'll see.
 

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I am not sure if Triumph Valve tips have the same Carburizing or flame hardening as camshaft lobes for example but once that surface hardening is gone, it will likely wear extremely fast. It smells like a geometry problem to me. Wouldn't cupping represent some sort of rotation of the valve to be possible ?
 

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I could be wrong but I think some of the problem is many high performance cam makers like Megacycle and Johnson want you to set your valve lash at 10k to 20k gap, then with the flatter "R" tappets and you combine that with a stiff racing spring and in my mind that is a lot of hard slamming on the tops of those valves.
from what I've seen you only need to use the hardened caps on the hipo motors.
It may be rocker geometry caused by the higher lift cams too. but in a stock motor you don't see to much of a valve cupping problem
 
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