Exhaust Valve Springs

[Dannopower]

Hi guys,

Just a quick question that im sure some of you guys with more mechanical knowledge may know the answer for, but I was wondering why we change the valve spring on the exhaust valves?

I can understand needing a stronger spring in the inlet valve, but the exhaust valve spring's only major job from what I can work out is to make sure its completely touching the rockers with the Cam lobes as they go around? Maybe im wrong, but the exhaust valve wont shut any quicker than the cam lobe will allow?

Our replacement exhaust valve springs dont have any sort of dampener spring, so that doesnt seem like a reason to change them?

I was wondering why it wouldnt be possible to just upgrade the inlet valve springs, meaning you can get 2 cars for the price of one box of replacement springs?

Has anyone even tested the result of changing the inlet valve spring only to see if there is any difference in doing the exhaust valve spring?

Cheers in advance.

Danno

[GOLDIE]

the spring tension on all the springs is low with the exhaust getting so hot they are loosing there tension and this why they need to be replaced and the fact that it is a good practice to do both and the extra time is not that much.

And the few dollars saved is it really worth it.

Ian

[Dannopower]

Thanks Ian.

I just thought from a mechanical workshop point of view, if you can do 10 cars with 5 sets of springs it would be cheaper.

I didnt realize the existing springs were actually loosing tension. Makes sence to do em while your in there I guess.

[phildub]

It is the exhaust spring that floats first due to the extra back pressure that is caused from raising the boost level,a typical rule of thumb is that the back pressure will get close to double boost pressure,if the back pressure holds the exhaust valve open the lifter pumps up and causes the valve to stay open.This is why you can hear the engine pop in the exhaust.