ALFAGTV6.COM

A while ago I said i'd come back and post a spring graph for V6 valve springs. Here it is, std V6 (12v and 24v) and the Arricambi hi-perf items. Very useful if you know how to use it, helps you set installed heigth for std and lightweight valves, combining safe high revs with minimal cam lobe wear.
Jim K.

Jim I hope you plan to explain how to use this chart in your new book. I am not ashamed to admit I don't know how. Looks like a great chart!

Jim,Invaluable info here...thanks..
Greg,compressed height vs poundage...

Oh, I see, by "length" he means compressed height. That's one nice chart. I hope it's in the new book.

Are the high-performance springs sold by IAP the same as the Arricambi type ?

Only one way to find out, buy a set and take it to a good machine shop with a spring tester. I will repeat myself here (this is getting dull!) and ask you to make sure its CALIBRATED!!! Case in point, the gauge we got from a large speed store in the US was NOT. Against my cautions the owner set his springs only to find out 2 months later that there was a difference of 10lbs (linear error) I found out by checking a spring in his tester and in our calibrated ones at work. End of BS. Now:
For a 12v V6, you're looking for seat pressures (valve closed) ~90lbs for high perf and ~100lbs for a high rpm motor with std weight valves. At 10mm valve lift, you're looking for ~175 and 180lbs respectively. However, you must also make sure you're ~1.5mm away from COIL BIND at your max lift! Now for lightweight valves...maybe std springs look fine but they're useless with max lift capacity of only 9.5mm!! Weight differences are very significant here and if you're good with physics you can calculate inertia of parts etc and come up with your own load figures, after taking into account cam ramp design..... Valve spring selection is therefore VERY important for the safety of your engine, especially so in the V6 where undue pressures will cause cam wear! Fortunately, Arricambi has excellent springs for both 4 and 6cyl engines, so for most applications you can rely on them and others like Spruell. I have used all of their springs so far with great results.
Believe me it gets involved when you look for and measure springs. To summarize and stop boring you, you're looking for (a)lbs at seat, (b)lbs at 10mm valve lift and (c)coil bind at least 1.5-2mm away from max valve lift. And finally (the wrench into the works) spring natural frequency should be 5 times the engine max rpm! Hah, gotcha!
Jim K.

Harmonics.......

BTW, I just found out, the 4cyl book is finally on sale; see:http://www.veloce.co.uk/shop/products/p ... s=SpeedPro&

Jim K.

And finally (the wrench into the works) spring natural frequency should be 5 times the engine max rpm! Hah, gotcha!
Jim K.

What you left out Jim is that you have to factor in the angle of the dangle, the heat of the meat, the fall of the ball and divided it all by the throb of the knob.

BTW You can afford to buy some birdseed for your pigeons this week. I just bought your scribbles. I am looking forward to see if it blends in well with all the other papers I have on a piece of string and hanging off the nail. Hope it's got pitchers...

JimGreek wrote:BTW, I just found out, the 4cyl book is finally on sale; see:http://www.veloce.co.uk/shop/products/p ... s=SpeedPro&

Jim K.

Does that superscede the old book, or add to it?

The book is about 35% bigger (textwise) with much more new info and also contains many of the old parts.
Jim K.