Whats up fellas? Long time, no ......type.

[fastTa]

The 26918's are 130 lb and may be a little too much for your stock lifters. They also make a beehive in a 105 lb, it's the 26915. Some guys use the LS1 retainers on the 918's and the 915's but you don't have too. The stock steel retainers or the 787's will work just fine. You can also go with the LS1 Titanium 772's. You can also use the stock locks with the steel retainers.

On aluminum heads with the 918's or the 915's you shouldn't have to touch the spring pocket or touch the springs. If anything you might need to run a valve spring spacer/shim to obtain the correct 1.800" install height. I have seen guys install them without any work to the spring pockets and/or the springs, but you know how engine building goes, every motor is different.

The 918's hit coil bind at roughly .660", so the .600" lift is fairly conservative. You could run .630" with no problems.

[N20LT4Bird]

OK, then. To recap......The 918's or the 915's can be used without machining. Both of them can be used with the retainers that are currently on my LT4 springs. The 918's would probably require new, upgraded, lifters. But the 915's could utilize my current lifters. The 918's can safely run .600-.630 lift without issue.

Of course, higher spring pressures would be needed on certain cams, but for a medium, street cam, would the 915's work well? What is the max lift I could run with these?

[fastTa]

According to Comp Cams the coil bind height is 1.140". This would mean that coil bind would occur at roughly .660" of lift. Normally Comp and other valve spring manufacturers will give the spring a max lift rating of a number usually .050"-.060" less than the measured coil bind lift. Another way of determining the amount of lift that a valve spring can safely handle is to look at the open load and seat load. Subtract the compressed height they rate the open load from the compressed height they rate the seat load.

The 915's have the same spring rate as the 918's, but they obviously won't handle the loads of a larger lobe on a bigger cam as well as the 918's. You could probably get away with the 915's on your stock lifters. Only one way to find out. Just take a measurement of your pre-load.

I would go with the 918's and spend a little dough on some good aftermarket lifters and then you will not have visions of your valvetrain sneaking up behind you and stabbing you in the back. Ok, maybe it's just me who has dreams like that!