This particular cam has very long ramps, at 0.006” the valve is open for 315 degrees, and closed for only about 20 degrees per degree wheel at zero lift. I had been advised multiple times by some of the slant racers over on /6dotorg to loosen lash, and never went past 0.018” maintaining a difference between intake and exhaust settings; having relashed the engine 10 to 15 times in the last 12,000 miles. These attempts yielded mostly poor results, and difficult carburetor tuning particularly at idle due to a poor vacuum signal aggravating power valve impute, and idle mixture control monitored via an o2 sensor.
I than looked for cam cards listed on /6 dot org of cams close to my cam, and most solid lifter cams of this lift and duration use lash adjustments in the 0.024” range; so I gave it a shot. With a little lash fiddling, and compression monitoring as able to tune my engine.
All this about my situation is just an example of how much lash adjustments can effect change in engine’s tune.
I used my experience as an example of how to manipulate cylinder pressure, and only recommended a 0.002” or so loosening of exhaust valve to see if it would correct for some difference in tolerances between lobes and valve train to even out cylinder pressures.
With a stock cam one has a starting place; 0.010” & 0.012”. Some of the /6 veterans clime they can listen to exhaust note and tapping of tappets and I believe them, tune a slant to be very smooth and responsive in a stock engine. To the inexperienced ear this is difficult, well for me anyway with a pronounced lopping engine, but compression tester enables one to achieve same results.
