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waste more power opening them,possibly harder on seats and valves

No proble at all, your red line will be a bit higher.

Been running them for last 20 yrs. or so without any problems. I figured they would last longer on a stock motor. I put them in figuring to use .400 lift cams years ago but never did.

if rest of the motor is still stock raising redline wont do anything other abuse motor.
stiff springs are harder to open which requires more power,not a really measurable amount i suppose.
the stiffer springs being harder to open would also mean they slam shut harder which is transfered to related valvetrain parts and seats.
putting stiff clutch springs in makes the clutch harder to pull in and is harder on related parts,what makes you think stiff valve springs react any differantly?
IM NO EXPERT,BUT I DO PLAY ONE ON THE INTERNET

The extra friction will cause an increase in oil temp also.
Are you always at the top of your Tach, or have a trans that jumps out of gear? The extra spring pressure would help in a over rev situation. Maybe get new stock springs installed at the correct height, or check those old ones and shim them back to the correct setting.

A spring gives back the same amount of energy required to compress it.

I wouldn't worry for a nano second about increased oil temperatures from the valve springs.

As for valve seat issues with that setup....ain't going to happen I don't think most people really know just how freaking hard those KZ seats get after 30 years :laugh: Cut them sometime...you'll see what I'm talking about.

I go through carbide blades all the time installing over size valves. In fact I just ordered some more today.....

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check the guides,measure your stock springs .if stock springs check out ok reuse em

larrycavan wrote:

As for valve seat issues with that setup....ain't going to happen I don't think most people really know just how freaking hard those KZ seats get after 30 years :laugh: Cut them sometime...you'll see what I'm talking about.

I go through carbide blades all the time installing over size valves. In fact I just ordered some more today.....

Heat treated and hammer forged at 9,000 rpm.

i replace them on every head i remove.
better then 30+ year old worn out springs.
been running them for 4 years on the 1100 with a stock motor with no problems.

larrycavan wrote:

A spring gives back the same amount of energy required to compress it.

I wouldn't worry for a nano second about increased oil temperatures from the valve springs.

As for valve seat issues with that setup....ain't going to happen I don't think most people really know just how freaking hard those KZ seats get after 30 years :laugh: Cut them sometime...you'll see what I'm talking about.

I go through carbide blades all the time installing over size valves. In fact I just ordered some more today.....

So the ol carbide cutting tools are soft aay :woohoo: I'm a stone man myself, especially now. I suggest taking the carbide to a metallurgist for composition conformation. Then start the almighty lawsuit rolling. :woohoo: I never seen carbide give so easy but I have not messed with it much. I'm surprised that they would need replacing all the time.