Sharp valve spring tails

[AndrisV]

Good day, or let's say morning!

I'd like to hear thoughts about sharp spring tail problem, as I have read a lot of literature about engine building etc., but somehow nobody has mentioned to take a look at this, or I don't have right books and internet links. Building every engine, we always try to be careful, not to leave any small detail or problematic spot, bet there is always a little naive hope, that respectable manufacturers do their job at best level. A few days ago, I was browsing for some suspension information on S1600 rally cars and found this infotech note from Citroen sport -> http://www.piecescitroensport.citroen.c ... ration.pdf ,basically it's a simple how-to guide for their clients of C2R2.

After that, I've checked a few sets of valve springs from various race engine "leftovers", most of those done around 2000-3000km in stage mode, and found out, that every single one had a bad groove on second coil (potential break point), because of sharp spring tail that rubs second coil. Mostly I use Schrick springs on our Lada engines, because this is well known and long walked route for our type of engines (no need to invent bicycle again) and even those had a sharp spring tail. So far I understand, that manufacturer can't do anything about it, unless somebody sands that manually or those springs will be twice in price. Checked a few other springs, same story.

Opinions?

[Guy Croft]

What you've described sounds perfectly logical. You need to change to interference (damped) springs to get rid of the resonance that's causing the coils to bang together. I've never had a tang fracture or coil fracture on damped springs (that is to say if kept inside their recommended rpm and matched to the cam).

GC