DonE

Has anyone used this method successfully? The write-up on Pelican makes sense, but I've never spoken to anyone who tried it.
Thx

PorschePhD

Don,

Yes, this does work and well. It works especially well when the elephant foot or the head of the valve is rounded and the normal gauge will not give a good read and or continues to tear when you adjust it. The backside method allows you to have more bite to accurately adjust it. Keep in mind that you will be using a .0025 feeler gauge as opposed to the .004.

WERK-I

True, but keep in mind the same principle apples to the rocker arm and cam lobe as well. The cam lobe becomes slightly concave due to the arm riding on the center of the lobe. Always take your measurements with the feeler gauge parallel to the lobe surface, not perpendicular to it.

DonE

Thanks much.

Rob S

Apologies if this is slightly off the main point here, but...

I don't know how the whole worlds seems to be able to take reliable valve lash readings on a 911 engine with a feeler gauge. I've been trying since 1976 with every type of feeler gauge holder doohicky ever made. I try it every 5 years or so, just to check myself and I've never been able to get reliable readings with a feeler gauge. I have no trouble achieving the correct clearances with a feeler gauge for more traditional engines, but for a 911 (or 930), with that deep recess and offset, there's just no way (I can find) to do it right. I've been using a dial indicator to do this task for30 years, and for me at least, it's easy and works so much better. Several years ago, I had a professional Porsche engine builder (who swears by the feeler gauge method) adjust the valves on one bank of my engine with his feeler gauge. I then checked them with my dial indicator. They were all off -- by a significant amount -- at 0.003 to 0.006 in., when I could hit it right on 0.004 in every time with a dial indicator. And using the dial indicator is so easy. Three questions: Why don't others use a dial indicator? How do you guys do it with a feeler gauge? And how do you verfy that it's right? And please don't tell me it's by "feel!" That's what they all say...

loot87

I don't know how you can even get a dial indicator in there.

kens911

Now thats something i would love to try. I have better luck getting the feel right than the actual feeler guage. I do them all with a guage then give them a wiggle if it doenst feel right I adjust using the guage again. Done it several times now on both cars and dont have the one odd one rattling any more. I whould much rather use a dial indicator.

Rob S

The dial indicator fits in there just fine -- even on a 930 with A/C. I use an aluminum holding fixture that goes over one of the valve cover studs. I bought mine in 1975 or 1976 from Performance Products; though I don't think it's available from them any longer, it wouldn't be hard to replicate. To use the dial gauge requires a little technique as well, and you have to be careful to measure only valve lash and not rocker arm side clearance. The way it's done is to measure the lash, rotate the dial gauge out of the way, make an adjustment and tighten the locking nut, and then verify if it was correct with the dial indicator. It usually takes me no more than three iterations to get it right. And each iteration takes less than a minute.

I agree with Ken that just pure "feel" absent a feeler gauge can often get you pretty close. But to me a feeler gauge is just about worthless -- I'd use a dial indicator to see if my "feel" was correct.

DonE

Sorry Rob, I don't follow your technique at all. Where are you placing the dial indicator? On top of rocker arm? On top of the adjustment screw?

kens911

Yes i'd like to know also is it the same dial holder you use for the cam timing?

Gary R.

Pics, a write up and the blueprint of the apparatus is required!

nathanUK '81 930 G50

This sounds great, the dial gauge method sounds as though it is something a DIY'er like me could do.

Jobs where FEEL is needed, takes both experience & familiarity which is something I don't have.

I have always payed a mechanic to do valve clearance checks.

Rob S

Okay, give me a few days and I'll take a pic of the dial indicator fixture. My engine is together and running, so I'm not going to open it up and do a tutorial at this time, but I could do that in the future, or on someone else's engine locally when I next get a chance.

In short, the fixture is an aluminum device that clamps to a nearby valve cover stud and is secured with a thumbscrew. Another thumb screw holds the dial indicator in the fixture; the fixture allows some rotation so that when both screws are tight, there is still a rotational degree of freedom to properly "aim" the dial indicator so that its plunger bears on the end of the rocker arm adjusting screw (or the locking nut on the rocker arm adjusting screw). Once the dial indicator is set, you grab ahold of the the rocker and rock it through its range of lash. Observe the needle swing on the dial, and look for 0.004 in. If the value is off, rotate the dial indicator fixture out of the way, use a wrench and screwdriver to adjust the valve to a new location, tighten, and re-check the lash.

The fixture is not the same as the Z-block used for cam timing. That's just a block of aluminum. This fixture is slightly more complex, but it would not be difficult to make. And I think it could be even simpler than it is. What you need is the ability to aim a dial indicator at the adjusting screw of your rocker arm, and its helpful if you can mount it, align it, and remove it quickly.

I'll take a pic or two over the next few days.

kens911

[QUOTE=Rob S;4594499] My engine is together and running, so I'm not going to open it up and do a tutorial at this time,/QUOTE]

I'm pretty sure thats a requirment here you have to pull it back out and take pictures and then post them. LOL thanks for the info after you post pics of the tool we all will proably have a better way of doing this now. I know I will.

JasonAndreas

Special Tool VW387 is one way but I'm not sure if it will fit without at least lowering the engine?