RE: Tapping valves will it hurt performance

[Jonas Karlsson <jkarlsso@metabolex.com>]

In a word:  
Yes. 

In a long-winded, yet more informative reply:

The thing with solid lifers is that you need some gap to allow for 
expansion when really hot. That is why you need to chack that the gap is 
right. You will hear some tapping as the cam fills in this gap. Bigger 
gaps will cause louder taps because as the cam rotates, the lobe 
contacts the lifter at a greater velocity since the contact point is 
further out on the cam lobe. Also -and this is key- when the gap is 
larger, the cam does not lift the valves as much, and for not as long. 
This will definitely hurt performance, although maybe not super much. 
  But wait, there's more. 
You don't want to reduce the gap too much. The reason is that the main 
way that the valves cool off is that they sit on the valve seat. If the 
gap is too tight, they will not seat properly, and possibly overheat. 
Overheating valves is BAD and will eventually warp your valves. Then 
you'll have some real performance problems. To compound this, the hotter 
the valves, the more the metal expands, and the valve stays even farther 
away from the seat. 
So, it is better to make the lifter gap too big than too small. 

HTH

Jonas
85 Scirocco


A1SCIROCCO wrote:
>I have a jh motor (solid lifter ) and the lifters are tapping 
>will it hurt the
>performace of the engine?
>
>
>
>Matt
>84 8v
>
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