One and a half with OEM lifters is good, but I've learned with typical aftermarket lifters, one turn is better. These are pretty forgiving as long as you stay within their "happy" range. You'll know if you've gone too far...the effect will be pretty much like if you adjusted solid lifters too tight. You will lose compression and your engine will feel "flat." It may backfire and it will generally misfire oddly at idle. If you find Sealed Power lifters, those are as close to the OEM as I've seen and you can tighten them 1 1/2 turns. Melling lifters aren't too bad, either...especially if you can find some made around 20 years ago or older. All of them are flat crazy expensive. The shop manual was written for the use of OEM lifters and they may or may not work the same as what you have. Good luck.
