[DeTomaso] DAN JONES YOUR INPUT REQUESTED

[Garth Rodericks]

Hey Chris,

I just had a beehive valve spring break on my new engine too, after only 987 miles. I was using the Lunati 74820-16 Pacaloy valve spring kit.

Specs:
1.88" installed height
377 lbs open
370 lbs/in rate
.600" coil bind

Max lift on my roller cam is .588", but the #7 intake valve broke with only .576" lift.

My machine shop did a root cause analysis on the failure and determined it was the result of coil bind.
Not all the springs achieve bind at the same compressed height - I didn't check for this when assembling my engine; I trusted the specs from Lunati/Pacaloy. Turns out I had less than .020" clearance between coils on some springs at full lift, which is insufficient.

A detriment of the beehive springs is that if one breaks, the valve drops into the cylinder - thankfully damage was minimal on my engine.
All my beehive valve springs are now being replaced with traditional dual springs - anyone want a deal on 15 beehive springs for a Cleveland? Ha!  :)
Good luck to you!
Garth
#4033 - the Banzai Runner
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://server.detomasolist.com/pipermail/detomaso/attachments/20140107/055125dd/attachment.html>