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"If you're using a go/no-go gauge instead of a feeler gauge, all you know is that you've adjusted a valve somewhere in a +/- .002" range"
Not so, a go/no-go of .017 to .019 is a tolerance of +/-.001 in, and with the educated "Feel" can get to better than .0005", using feeler gages. If you get the right feel for it, the adjustment is zero tolerance, but not that necessary unless you're wanting an 8k rpm top end and a cam that'll send the hp number up while doing so.
If you are running a rally or race cam this method is the only way to get it near perfect for all the valves. The cam running large overlap, when the crank approaches the intake stroke, all valves open partially, the same amount simultaneously. In a high rev motor running a large advance, ~18-24 deg, this is a big component to gaining maximum HP.
I've probably adjusted B20's more that 100 times, and can say without exception that this method is the most exact, one which was taught to me by a Volvo racing team mechanic. It works, and there will be no doubt the valves are evenly adjusted.
Honestly I have not read the VClassics procedure, but trust JP to know what the better way to go is. As far as adjustment using the crank rotation, we are in agreement.
Also note that if your using a performance cam with large overlap,(R-sport rally cam, as I have had in the past), when a single intake valve lobe is at zero position on the back side of the lobe, all other lobes will have spring force on them except for the opposing cylinder exaust valve in the rotation, 180 degrees apart. This is to say that you can do two adjustments per crank rotation, but I always do them sequentiallly, just to keep better track of which one I did.
On my B230F modified N/A motor I splurged and had the dealer do a 'Zero tolerance' valve adjust and gained big improvement in HP using a VX cam. The reccomendation as noted here, was to stay above the minimum clearance, and set to .019"
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'89 245 sportwagon, destroyed by hit & run driver, RIP. '04 V70 2.5 T Sportwagon, 12k mi and '91 245 5-speed, 209k mi, replaced the '89
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