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On 1 Sep 2002, at 1:04, John Jaranson wrote: > I pulled both the #1 and #2 exhaust valves from the head. It is clear that > the three angle cut is ok on #1 and the valve is kissing off in the proper > spot on jsut the outside diamter of the 45 degree valve face. However, it > looks like #2 has pounded itself into the seat so it is trying to kiss-off > along the whole 45 degree surface of the valve. Might even only be trying > to kiss off in the inner diameter of the 45 degree face. If the seat had originally been mating at the outside edge of the valve 45 then wearing into the seat should have caused the seat to develop a vertex where the 45 meets the outer margin. If this is not there, then something else may be going on. Traditionally, the 3 seat angles were ground with 3 different stones, but today's head machines often use shaped carbide cutters which can machine all 3 angles at the same time. I wonder how yours was done. Is it possible that the seat sealing area was originally too small, or that it was never cut to the right angle? A machinist will test the hardness of a piece of steel by seeing if a file will bite into it. You might be able to do something similar to the valve seat. See how hard it is to scratch a part of it that is away from the sealing face. I'd be really surprised if the # 2 seat had lost its hardness, but I suppose it's possible. OTOH, it seems really unlikely for the cylinder that appears to have been running cooler. > There is no evidence that the seat itself is receeding into the head. Just > the valve into the seat. This is a good sign, and just points out how important it is to look closely at things before jumping to conclusions. > I compared the lengths of the two valves and there is no observable > difference in their lengths. I assume you did this with a good caliper so that you could really see any significant change. The new valve lengths are listed in most manuals. > I figure I lost 0.020 or so since installing the motor. Plus the adjustment > screw for #2 exhaust is just about all the way out. I agree that that's a lot. These are the swivel-foot adjusters, too, aren't they? > One other observation. #2 exhaust valve guide is looser that #1. All the > guides were new and tight 7,000 miles ago when I rebuilt the engine. Any > possible connection? Certainly food for thought. Is the wear enough to disguise a seat wear vertex from the outer edge of the valve 45? The swivel-foot adjusters usually make for less wear; is there any chance that this one was binding somewhere and not sitting flat against the end of the valve? > Thanks for the advice so far. I will probably take the stock springs from > the original 1600 single port and install them in place of the hi-rev single > springs. It will give me an excuse to do the autopsy on Sophy's original > engine. I will also lap the cylinders on a glass plate and then lap them > into the heads. If you have a vise, you can place the 2 springs end to end and compress them in series. Squeeze until one of them is at the measuring length from the manual, then measure the other one. This will at least give you some idea whether these 2 springs are well matched. - ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ------------------------------------------------ To unsubscribe, E-mail to: <type3-off@vwtype3.org> For more help, see http://vwtype3.org/list/