Pro 1 #11971143P

[BERT]

The advertised max lift for the assembled head #11971143P on the web site is .690 lift. The advertised max lift on the specs sent with the assembled head is .650. I'm confused Can anyone shed some light on this?

[Trmnatr]

The advertised max lift for the assembled head #11971143P on the web site is .690 lift. The advertised max lift on the specs sent with the assembled head is .650. I'm confused Can anyone shed some light on this?


Im not sure because i always buy bare heads. Hopefully Dart Vader will swing by!!!

When i start with a bare head i like Manley NexTek, Crane or Manley H-11 and certain select Crane chrome silicon springs are good.

I think Dart gets their springs from the same place Comp Cams gets theirs but again Dart Vader can help out on that

[Dart Vader]

I asked one of the techs about this and here is what he said:
"The spring does list it as .690. However, running a spring right at max lift is not really the best way to control valve-train, it will also decrease lifespan. I would recommend using nothing more than .670 lift, before subtracting lash, which would typically put you at the .650 lift area."

Hope this helps!<!-- / message -->
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[BERT]

Thank you for the clarification!

[Awesome Bill]

Actually, most spring companies now would rather run the top side of the spring within .05-.060 of max because the spring can control with load better on the top side than with less of the total. Because with rpm, weight, valve train stability, harmonics, small base circle cams etc. etc., the spring being closer to its greatest yield actually keeps the spring alive longer! We run everything right to the max and have seen less spring failure for the last 2 years. Got this right from Comp, Manley and Associated and have done way better with breakage. A bad spring or batch of them, is just that, junk and they will break no matter. But with high side loads being up on top, makes the complete valve train more stable. That is is if everything else is compatible.