Date: Mon, 9 Dec 1996 02:19:39 -0800 (PST) From: Mike West Subject: Cams & Valves Notice the title? I'm bucking for "Archive" here babe. While you fashion hounds were debating the "political correctness" of "Orange Stool" and measuring your curtains, I was studiously reading a book called " Basic Cams, Valves & Exhaust Systems". Hydraulic vs Solid Lifter Cams: They don't want to talk about it. The most I could gather is that the Solid has a brief flat spot before "ramping" again. It seems to need this to "catch up with itself", then the word "Valve-Lash". You don't want to know. On the Hydraulic lifter, having its self-correcting "zero back-lash", it can start to "ramp" at once. So they do. If this is all there is to it, then it sounds like you could use hydraulic lifters on a "solid" cam but not the other way around. "You first". :-) The book was published in "74, talks about how you just go tell your "Cam-grinder" what your tire diameter and final gearing was and he'd grind to put your max torque there. I wish I had lived in those days. Valve clearance: The .004" to .006" to the .006"in/.008"exh. First, it was determined by VW that the max expansion of all "the goodies" worked out to .004" at standard operating temperatures. The intake valve is always being cooled by incoming fuel/air. The exhaust on the other hand is always being "heated" by gasses as high as 1600 degrees. It may attain temperatures of 1300-1400 degrees at the tulip/stem. This old book talks about the new-fangled "stainless valves". It seems they have a 40% greater "expansion rate" than the old "steel" valves. Remember the "leaded gas"? Forty perecent of .004" is 1.6 mil round to two. Ergo the .006. Experience probably got them to go to .008" on the exhaust in the bigger engines, ie the type 4. This also might apply to those running "big bore" or even "California Lean" type 1's. The only way I can think of to get the real "skinny" on your own engine would be a "hot compression test". "You first". :-) There is more, if you run solid lifters "sloppy" you'll increase your "low end" torque. Always with the sacrifice to your "high end". The reverse is also true. Meaning running "tight" will increase "high end" with a sacrifice in "low end". In closing I'd like to say I hope this "technical stuff" bugs you "Interior Decorators" as much as your damned Curtains bug me. :-) west