I have a set of LT4 valve springs that I did not install. I used Manley springs, because my "expert" said they were the best and I shouldn't go with the GM stuff....

Well, now that I have busted a spring and am into the engine again, his motto is to replace with another set of Manley springs, yet I am loathe to repeat this mistake and feel the LT4 springs are fully capable of 6500 rpm without float, etc.

Does anyone have the actual specs on the LT4 springs?

 

i dont have the pressure specs off hand but if your cam is higher than 0.525" (total lift with either 1.5 or 1.6 rockers) then you will reach the max of those springs. They are designed for the LT4 hotcam and the LT4 motor with the weaker cam that was in the Grand Sport Vettes.

It has been noted from a few engine builders that the retainers are junk too. They tend to break and then the valves drop..... so i ditched mine for comp cam 987 springs. All you need with those is to grind the spring seats.

 

http://www.sdpc2000.com/catalog/877/...Spring-Kit.htm

 

What cam are you running?

 

Yeah what he said.

The LT4 springs are marinal for the HOT cam what people often forgewt or fail to consider is that the LT4 valves were lighter than LT1 valves, so LT4 springs with LT1 heads and a HOT cam is really pushing the limit. That said you don't ever hear of them breaking. Also there are very few companies capable of making valvesprings finding the right specs is more important than the brand because the same exact spring is going to be sold under several names.