So i have zippers big billet heads . 2.0 intake and a 1.62 ex valve size , i run woods springs and woods 630 lift tw9bg, when i got the heads they came with valve lash caps and zippers said i need to use them so i did, ive had the heads on bike for a few years but i am just wondering why needed the caps was it for geometry?? , ive since done things like pinned rocker arms and so on, and have checked the caps they seem fine very little wear,
thanks for the replies
Lash caps change geometry. You want the rocker arm pad in the center of the valve stem. If the rocker arm pad is too far forward or backward it messes up the valve guide.
I used them when I was drag racing, big cams and really tight tight springs would waste a set of guides in a run or to.
To be clearer, you want the rocker arm tip on the center of the valve when the valve is at 50% lift.
Do you? Or do you want it dead center at 25% and 75% lift? (likely a little different as the arm swings and arc) That way the swipe is centered on the valve end, assuming that the plane where the rocker contacts at the end of the valve intersects the rocker shaft axis at 1/2 lift.
Well, yes you could be right. It does depend on the angle of the stem, the amount of lift as it relates to the pivot of the rocker arm. In the end you want the swept area on the top of the valve to be centered as much as possible.
Lash caps are used on valves that don't have a hardened tip.
The lash caps are a way to lengthen the valve stem tips to correct the geometry. All fine and good but when that lever end, the valve side is corrected, it leaves the pushrod side improperly clocked as it related to the pushrod end. Your neighbor Dan Baisley can fix that and supply corrected geometry roller rockers he makes if you want to go the full route.
"In the end you want the swept area on the top of the valve to be centered as much as possible."
More importantly the swept distance minimized
:agree: and what Larry said is true also. Trimming valve stems can break through the case hardened tip or make it too thin to have a long life.
Majority of steel valves have hardened tips welded on them. Usually .040" - .060". You can usually see the color change .Stellite is usually used. Always be careful when you try to re-grind the tip. :wink: Most of the titanium valves I use, are unfinished length. I size them, add a radius keeper grove, and add a lash cap on the titanium tip. Pro/Stock and Pro/Mod import bikes.
John
maplegrove.jpg