Wow, great info gupp.
Thx for the reply and it made me think enough to do a little research on this #12551483 spring - yes u were right, i posted the wrong part number. Now first i found that spring was used in quite a few GM crate engines (LT4 Corvette, ZZ4, CT350/400 and ZZ383 Engines) and had to wonder why its not working for our homemade conversions. Well i found all those crate engine heads used the same light weight vlvs:
LT4 Valve, Intake 2.00" (50.8mm) Hollow stem Weight:85 grams, 3.00 ounces #12555331
LT4 Valve, Exhaust 1.55" (39.4mm) Sodium filled stem Weight:75 grams, 2.65 ounces #12551313
Where the LT1 valves weigh in much heaver:
LT1 Valve, Intake 1.94" (49.3mm) Solid stem Weight:110 grams, 3.88 ounces #10241743
LT1 Valve, Exhaust .50" (38.1mm) Solid stem Weight:95 grams, 3.35 ounces #12550909
It don't take many brain cells to realize that spring maybe adequate for the light LT4 type valves but not the heavier solid stem vlvs on an LT1 - at high RPM. So now i'm a believer here. But the bad news is now i on search for replacement vlv springs for my LT1.
Thx again gupp,:LS1LT1flag:
cardo0