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les_garten les_garten is offline
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Join Date: Jun 2003
Location: PSL, FL
Posts: 861
Originally Posted by Rob 930 View Post
For further discussion about valve adjustment by this method, and about my experiences regarding the validity of using a feeler gauge, you might check this thread on Rennlist:
Valve adjustment is a learned skill no doubt. All these methods work perfect if done correctly. The backside method makes it where you arrive at perfection quicker and with less frustration.

DonE, I didn't have to bend my feeler gauges, so I'm not sure I understand what you ran up against. I use straight, "standard" sized feelers. I stick the .0025 in there and leave it. I turn down the adjustment until I feel the adjuster "touch". I tighten about a third holding with a large stubby screwdriver. I check the feel of the .0025 feeler. If It's caught, I loosen up a little. I always watch the "clock" angle of the adjusting screw to help me determine how far to move the screw. When the .0025 is a tight drag, I pull it out and make sure I can work it back in. It should go in the gap, but be a little difficult to get in. If it is not tight going in, your lash is too loose. I check with the .003 to make sure it it is the "slightest" amount of loose. If I get a good tight drag, the .003 has no way of going in. This is the easiest and most accurate valve adjustment I have ever done on Porsche's.

As far as the Hot lash stuff on Rennlist. I think tjis is a non issue on a street car and a theoretical one on a Track car. All you have to do is have enough lash so that the valve seats and transfers heat.

Noisy valves are better than silent valves, ehhh?

Porsche designed these cars to be street cars in Germany. Which means sustained driving at well over 100 mph. I lived in Stuttgart in the 70's, believe me, you don't hang out in the left lane at 100 mph or less for very long. So the elves in Zuffenhausen figured .004 was enough to compensate for expansion due to heat with these bad boyz doing what they were meant to do on the Autobahn.

There's a ton of folks on this list with high HP 930's, who uses a lash different than .004?

Surely Stephen at IA would know about this?

One of the advantages of a Porsche in this regard is that we are all aluminum. A lot of a Porsche's engine parts expand and contract at similar rates, thus making clearances more predictable.

The backside method, at least to me has the advantage of being easy, repeatable, and consistent. Both methods must be verified. The traditional method makes verification a pain in the ASS. That's the real difference in the two methods.

just my .02

---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT
Old 02-01-2008, 04:16 PM
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