Got my 3 bolt heads back and the shop put double springs....no charge...had them and thought I would like.
Drag race VW buddy says he used single as it made the engine work too hard
...any thoughts?

I was always taught that the second spring was more for harmonic control of the main spring than added seat pressure. I don't see the problem.

can i ask who did your head work?

If you don't have the RPM or lift to require them, all they'll do is raise oil temperatures.

we always ran them on race motors
never on street motors

I don't know if it's still the case, but in years past a lot of cutting had to be done to fit the double springs. It made the already none-too-strong Type IV head even more prone to cracking.

And, yeah, if you don't need them they're not something you really want.

--DD

heavy springs take power to squeeze them.

Thanks I will lose a spring and go back to normal.
Rodyguy, always used Jerry at NW Con Rod but I sent some parts I had saved from 40yrs driving 20 different Pcars...and he knew I was putting together a red headed step child '912e' (mid 70's 911 w T4) and said he had some heads he would work up and mail...he doesn't do much machine, just restores...but the work he does "Uncle Ferry" would like

Whoa there!
Once the heads have been machined for dual springs you cannot go back to single springs.
At least that is my understanding - maybe there is a collar or something you can insert to make it work, but I dont think so.

stugray...really? I am now stuck?
the "friendly favor' now looks like
not too great...