ive herd about people putting double valve springs in 4k to help preformance, was just wanting to kno what exactally this does? how does it help?

 

cheers guys

It will have no performance improvement on a stock motor. Its only necessary if your cam has been changed, because cams can often run higher lifts, the spring rate needs to be changed to match the cam.

Edited June 5, 201214 yr by philbey

whats the part number for em does anyone know ?

I reckon it you perform a search them you could find philbey dish it out at least 3 times!!!!

Well double valve springs can give you added rate ie lbs/inch most importantly for more aggressive cam profiles,

also they are said to reduce or cancel out spring harmonics by having 2 springs of different harmonics together.

 

Its not just the fit of the spring, the installed height and rate through the lift of the cam is equally important as is

a retainer to stop spring walk of the inner at least and the outer if possible.

 

Check out beehive springs, meant to be the latest spring innovation but requires smaller retainers.

Edited June 6, 201214 yr by styler

part number is 4220 from crow but i was told when i got mine last year that they were one of the last set's

Just check with:

 

1) Installed height

2) seat pressure lbs/inch on valve

3) nose pressure lbs/inch on camshaft

4) Coil bind height

5) Shims / Locaters / Retainers / Collets / Lash Caps etc

I reckon it you perform a search them you could find philbey dish it out at least 3 times!!!!

 

At least. Dish best served cold, followed by a dessert of: do you really need them?

 

Broken record?

 

Well double valve springs can give you added rate ie lbs/inch most importantly for more aggressive cam profiles,

also they are said to reduce or cancel out spring harmonics by having 2 springs of different harmonics together.

 

Its not just the fit of the spring, the installed height and rate through the lift of the cam is equally important as is

a retainer to stop spring walk of the inner at least and the outer if possible.

 

Check out beehive springs, meant to be the latest spring innovation but requires smaller retainers.

 

This is a common misconception; Doubles can be designed with a lower spring rate to allow for greater lift without spring bind and high nose pressure! In the case of my crow 4220 doubles, they are a lower spring rate than the stock 5K springs.

 

They are a direct bolt in, they require no change in retainers and you may wish to shim them up if you aren't running enough seat pressure. I would suggest that you would only run the 4220 with BIG lift. I run about .480 lift, .1 over stock.

 

Keep in mind that I ran that lift with stock springs for a good couple of years before one broke.

Ah indeed philbey I do agree such is the "can" give you added rate :)

Edited June 6, 201214 yr by styler

Yeh fair call mate. If you go back through the pages, there are a lot of claims that they give you high spring rate, then the flat earth society jump on the whole 'losing engine power' bandwagon.

 

good times.

Edited June 6, 201214 yr by philbey

the 4220 are double the seat pressure compaired to the stock springs.

Yeah it's interesting the whole lost hp seat pressure vs equal drivetrain equalibrium debate....

Including valve seal vs volume lost etc...

Edited June 6, 201214 yr by styler

How'd you come to that conclusion Evan? Not that I disagree but unfortunately I've lost my calc spreadsheet I made, I calculated stock spring rate by measuring them up.

 

If I recall I had similar seat pressure to stockies but lower nose pressure than with the doubles.

Edited June 6, 201214 yr by philbey