Who runs dual valve springs? Who runs singles, and why? Reason I ask is my engine builder likes single spring setups... I recently put in a fk-43 cam to replace the one that rounded a lobe, running single springs.. The cam card says to run dual springs, not exactly sure why. I did manage to bend a pushrod last season, which I think might be because of the single springs not closing fast enough. Engine builder thinks dual valve springs wear out the cam faster, but I'm thinking if the cam is designed for dual springs, it should be hard enough to withstand the extra pressure. Thoughts?

You definately want duals on that FK-43 because it is a pretty rampy cam and will go into valve float at a relatively low RPM with singles. Not enough valve spring pressure tears up WAY more parts than too much.I have run springs with nearly 500 lbs of pressure at full lift without a single problem.

I learned the hard way, not worth it, if you have a cam profile like the FK-43, run duals, the only way to run singles is stock motor cam, other than that, duals........I personally like the VW 650 springs in my heads, they are well worth the $$$, any good engine builder should know that if you set the spring height up correctly when installed in the heads depending on the cam and rockers with dual springs will not hurt the valvetrain at all just like Creech said....

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"Loud pipes saves lives"

I have run several fk 43's and fk 44's and always ran dual springs.

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Maybe you should chug on over to mamby pamby land....

X-4 Dual spring are a must on FK cam and ratio rockers . Drews can get Engle cams grond on a harder core.

I think the only person going to say run singles is the guy that told you that,lol.I would have him explain his reasoning for even saying that.but I would not want to run singles IMO.Chad

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NOW GAS IT!!!!!

Sounds like the motor guy don't know how to break in a cam.Dual for sure

Ahh, in his defense, he is an older guy and I suppose single is the way they used to do it. His theory is the extra pressure wears out the cam faster. But got a set of the springs on the way and gonna put'em in so I don't have to worry about it. Thanks for the help guys.