Valve Springs - great article

[AzCoupe]

We have had lots of discussions on valve springs, coil bind, and proper spring rates. Here's a great article by Crane Cams. If you have had any questions about springs, here's your answers.

http://www.cranecams.com/?show=faq&id=5

 

[wsa111]

Mike, that technical article from crane should open a lot of eyes of guys trying to use todays cams using yesterdays springs.William

 

[CZLN6]

Howdy All:

Thanks for the reference Mike. May I add that there is also a great, general information article on "Camshaft Science", in the July 05 issue of Mustang and Ford. It is by Jim Smart and Comp Cam.

Bill- I don't think the issue is so much between "Today's and Yesterdays springs" as it is knowing the critical details of dimension, tolerances and needs. The bottom lines are; you need what you need to control valve action- any more just accelerates wear, lighter valve train components are better- to a point, measure, Measure, MEASURE! And recheck.

Adios, David

 

[wsa111]

Mike, I will have a look at the latest crane book, but i believe the keepers which are -.050 & + .050 are not available in the 5/16 valve stem, just the 11/32'nd & 3/8 's. I may be wrong but will do some research on that.

David has made a good point, the proper measurments are the key, when you have your cylinder head at the machine shop, tell them the installed height you need the springs to be & if necessary they can machine the valve spring surface at that time & save you a trip back to the shop. Seems like most of the heads I've done need the seat machined to achieve the 1.700" installed height.

If you are using a stock camshaft then the single spring is fine, but if you are using a camshaft with very aggressive lift you need to use the spring rate specified by the manufacturer of the camshaft.
If your camshaft manufacturer only recommends 50-60# on the seat you have a camshaft more suited for mild engine for street use.
That perticular camshaft has a very slow rate of lift per 10 degrees compared to a real performance camshaft which will require at least 80#- 110# on the seat to give total performance. The camshaft with 50# on the seat is mild in the world today , compared to a true performance camshafts
And I guarantee you it will be a single spring with damper or a dual spring combination.
Definately on these high lift camshafts & higher than stock rocker arm ratio you need to check the retainer to valve seal or guide for proper clearance.
With my 1.65 rockers which produce .495 lift & using the all teflon valve guide seal I had to machine off .040 from the bottom of the retainer for safe clearance. Do it right the first time. William