hi,

i'm getting my heads milled this weekend and after removing all the stuff, i found 6 broken inner valve springs. anyone know, why the broke? does PT use cheap springs? or is it because of some 7000rpm 1/4 runs? (revs good to this point, according to my tach).

i think the new springs will be these.

Springs
Retainers
Locks
Locators

i've read an article about these beehive springs. looks good to me. although expensive... hope they'll last longer

and can someone suggest me some valve stem seals? the better ones, which last longer than a few 100 miles....

thanks,
nebu

 

Those arent springs, theyre dampers. I've seen them break before for various reasons but the shift point is likely what did them in. They generally float inside the spring and probably couldnt take the movement at that speed.

 

Looks to me like you're lofting the valves causing the springs and/or dampers to crash solid while open. Too much rpm. Put a rev limiter on it. If your valve seals are getting torn up, thats a good clue.
You're probabily reving it higher than you realise and way higher than nessessary to get best acceleration. You shouldn't have to rev higher than right about 8% higher than what ever point the motor makes peak HP at. So if it peaks at 6000rpm you should be shifting it at 6480rpm OR LESS! Unless of course some one else is paying the bills.

If the motor we're talking about is the one in your SIG, you're reving it about 2000rpm higher than you need to for best ET.

 

yeah i know 7k is too much. i did some 1/4 runs last year with 5k, 6k, 7k shiftpoints. around 6k seems to be the best. never been on the dyno yet.

 

just for the records... i milled the heads .024". assuming .006" for one cc.
result is 56cc. either the heads have wrong specifications or the calculation is not right.