Hey Guys. I am getting ready to do a cam swap on my lt-1. I am going with the comp cams 503 extreme energy 224/230 with 1.6 rr's. The main things is that I am going to stick with the stock heads as I have hit the mid 12's at 107(M6) as a bolt on car on dot's, so I want a spring that doesnt require machining of the spring pockets for the stock heads. Comp cams rec. the 986 dual valve springs, but if I am not mistaken, you have to machine the pockets with these springs. What springs will work and be good springs with this cam? Any info will be greatly appreciated.

 

I'm running a set of EX 612 springs on my setup. Combination Motorsports sells a kit with locks and retainers for $110. Give Brian or Seth a call and they can set you up with what you need.

 

I had this same problem when I selected that cam. In the end I went with comp 987s eventhough they required machining of the heads. But what most people dont know or say is that you dont necessarily have to machine the seats. What I did instead was cut away at the locator where it wouldnt sit flat on the head. For most of them there were 2 areas that required very slight notching on the locator to sit flat in the seats. The locator is actually quite a bit larger in diameter than the springs anyway so there is plenty of room to notch the locator w/o any effect on its function. For some reason comp just made the OD of the locators required for the 987s really large so they dont fit LT1 heads but the springs themselves fit just fine. Ive been running my car like this for nearly a year and very hard so its a proven solution to this problem.

 

I believe the comp 941's are the strongest springs you can run on un-machined heads. I have them on my car right now. The only thing i am worried about now is collapsing a lifter. If you go with really strong springs and wanna rev it, you might want to consider comp-r lifters.

-Stu