TheSamba.com :: View topic

Thu Apr 23, 2015 8:51 am

I burned up three exhaust valves driving from Pennsylvania to Los Angeles in 1986. The dynometer said the engine was putting out 7 horsepower. The guy wanted to know how I made it across the country. I told him a JB Hunt driver agreed to let me draft behind him all the way across on I-40, we did pretty good all things considered until I had to go down I-15 and he continued on up to Salt Lake. The crawl over the El Cajon Pass was excruciating.

The reason I burned three valves is because I had made a bad decision that affected all of my clackityclacky valves. The valve stems were a bit stoved in from both the approximately 70,000 miles since the prior rebuild and the fact that the rockers had not been shimmed to ensure that the adjustment screws were slightly off-center . A flat feeler blade only contacts the outer circumference of a stoved in stem and covers up the "bowl" underneath. Even with a serious drag on the blade, the adjustment screws were pounding the centers of the bowls. I don't remember exactly what decision I made to compensate, but it was wrong . . .

. . . yesterday, I realized that I have some valve stems on Chloe that are a bit caved in as well. The engine had developed quite a tackitytack at idle, even with draggy feeler blades. So I thought to create a new method of valve adjustment that would be similar to the hydraulic valve adjustment method, so I would not have a feeler blade acting as a plank over a bowl.

If the valve adjustment screws are a 1.00mm pitch, and our adjustment specification is .15mm (.006"), why not back the screw out a precise number of degrees? Then I won't get thrown by a dished stem.

1mm pitch / 360º = .0027 X 55º = .015mm required clearance.

So, that is what I did.

A turn adjustment screw with fingers until it contacts valve stem

B turn backwards 55º (I did 60º)

(I will bring a spare set of heads* with me, just in case I have screwed up again):

*the heads that were originally on my engine got their seats destroyed by too-small fuel injected beetle exhaust valves. Now they have new Osvat exhaust valves and new exhaust seats that hopefully will know how to stay in place. I have never owned or driven a VW with replacement seats. but the day is coming.

Thu Apr 23, 2015 9:38 am

Ah yes, the simple gut appeal of Geometry!

I'd like to know where to get a set of those little screw-head protractor thingies you show.

Thu Apr 23, 2015 9:49 am

And I'd like to know where to get a pair of reading glasses strong enough to read them in place :lol:

Sounds like a reasonable theory Colin, the only potential variable would be unevenly worn valves or adjuster screw tips, if everything is dished/domed somewhat evenly it should work.

Thu Apr 23, 2015 9:54 am

Use chromoly pushrods that are set to a "loose zero".... problem solved.

Thu Apr 23, 2015 10:00 am

By now I would think you would be able to adjust them by ear?

:lol:
Tcash

Thu Apr 23, 2015 10:44 am

busdaddy wrote: And I'd like to know where to get a pair of reading glasses strong enough to read them in place :lol:

No kidding!
That is why I am making a 60* screwdriver blade cut-out template. Merely close the clearance with your fingers, stick the template over the screwdriver in the screw slot, rotate template to start position, now turn screwdriver counterclockwise until it hits the stop position.

busdaddy wrote:
Sounds like a reasonable theory Colin, the only potential variable would be unevenly worn valves or adjuster screw tips, if everything is dished/domed somewhat evenly it should work.

I was thinking that uneven screw tips or valve stems would also mess with the feeler blade feel. I am hoping this is a yours-truly idiot-proof guarantee of .006" because if there was an actual .007" or .008" under a tight feeler blade-with-dished-valve stem, my summer banzai will surely make it worse. I have a demanding schedule and route this year.
Colin

Thu Apr 23, 2015 10:56 am

Well there goes the feeler blade industry. :D

Thu Apr 23, 2015 11:07 am

Inspect your adjuster screw tips under at least a 10x loupe. Even moderate miles wears a flat spot with side ridges that are sharp. Turning the screw changes the aspect or angle of those riddges to the feeler blade giving a drag fell that may fool the user.

Also as I have stated numerous times.....most valves are two piece. Even the most perfectly made two piece valves have internal stresses that change the rate at which they expand...relative one valve to another.

One piece valves have less stresses but are different from valve to valve as well.

This is why long ago I found much more accurate valve adjusting with relevance to running condition....but adjusting valves hot. I also got away from the wear ridge issue with 911 adjuster screws.

Your turn degree method also makes great sense because there is tolerance in the thread loading between lock nut and screw. Really sensitive adjusting can be off thee moment you tighten the nut. This probably has most to do with wear and tolerance to thescrew therads in the rocker arm.
Knowing the screw position to set it by angle would be helpful. Ray

Thu Apr 23, 2015 12:12 pm

raygreenwood wrote: ... Really sensitive adjusting can be off the moment you tighten the nut. ...

If you have three hands it is quite simple.

Do we have a picture anywhere of a shop coat VW mechanic with three hands for feeler gauge, box end wrench, and screwdriver?

I, unfortunately, have only two hands and the screwdriver, correct gap, tighten the nut, gap too tight, loosen the nut, turn the screwdriver, tighten the nut, check the gap, ad infinitum, is too familiar. It can be done but it often involves dropping the feeler gauge, finding where you put the screwdriver down, the wrench falling off the nut and hitting you in the face and dripping oil.

Been there done that.

Aloha
tp

Thu Apr 23, 2015 12:18 pm

raygreenwood wrote: Inspect your adjuster screw tips under at least a 10x loupe. Even moderate miles wears a flat spot with side ridges that are sharp. Turning the screw changes the aspect or angle of those riddges to the feeler blade giving a drag fell that may fool the user.

Yes, people should be punished for neglecting the advantages of frequent valve adjustments on preventing radical wear spots. Also, I like to blame the valve adjustment professional for pitting caused by dirty instruments.

raygreenwood wrote:
Also as I have stated numerous times.....most valves are two piece. Even the most perfectly made two piece valves have internal stresses that change the rate at which they expand...relative one valve to another.

Back in the .004" days, I could see where the above might have an effect on engine health, but when the factory increased the clearance by 50% in one fell swoop, I think there is a fudge factor with the Type 1 engines. Type 4 engines being designed with the .006" (.008" sodium), I follow without question.

I wonder to this day if I could get away with .004" on my 1600 if I was "conscientious". It has been a long long time since I have had to deal with pecked valve stems from too much impact forces, and it is why Chloe gets Porsche adjusters with the next set of heads, to wit: see below.

raygreenwood wrote: I also got away from the wear ridge issue with 911 adjuster screws.
Ray

Thu Apr 23, 2015 12:30 pm

Has any own owned or used one of these valve adjusting tools?

Aloha
tp

Thu Apr 23, 2015 12:44 pm

Amskeptic wrote: If the valve adjustment screws are a 1.00mm pitch, and our adjustment specification is .15mm (.006"), why not back the screw out a precise number of degrees? Then I won't get thrown by a dished stem.

1mm pitch / 360º = .0027 X 55º = .015mm required clearance.
I like the idea -- it is brilliant in its simplicity. Why did it take you (us) so long to think of it?

So, are the threads always 1-mm pitch?

Also, 60° is reasonably easy to estimate by eye, even, if you have an eye for geometry.

I like it! I like it! We'll see how it looks come August in the southwest! :)

Thu Apr 23, 2015 12:45 pm

Tom Powell wrote: Has any own owned or used one of these valve adjusting tools?

Aloha
tp

I used one once, but the whole issue of changing clearance as you do the final tightening occurred with it as well. You could not see the "prefetch position" to do the final-tighten-moves-screw-with-locknut method for those valves so afflicted. It worked OK with cooperative screws and nuts. though. So who here had this tool that I got to sample way back in 2004 or 2005?
Colin

Thu Apr 23, 2015 1:02 pm

I'm wondering why you just don't stone things flat? I would think it would be a simple jig, especially if you built it off a rolling chisel sharpener that runs on a whetstone.

Imagine a tight fitting sleeve on your screwdriver shank. Tight enough to stay, loose enough to pivot. The screwdrivers with removable shanks would be ideal, and they have the parallel tips you want anyway. Put two pointers on the sleeve, like wires, 60* apart. Now the screwdriver goes on the closed screw, you zero out one pointer by rotating the sleeve and rotate the screwdriver to line up the other.

You don't need all the degrees on the degree wheel, just 0 and 60 (I think you said 60), so a pair of pointers is enough, and easy to read.

Thu Apr 23, 2015 1:38 pm

One flat of the adjuster nut is 60 degrees as well, set the loose nut so a point aligns with the screw slot, hold it steady and turn the screw to the next point, then hold screw and tighten nut.

Thu Apr 23, 2015 1:43 pm

Be the first one to own one.

:lol:
Tcash

Thu Apr 23, 2015 1:48 pm

Tcash wrote: Be the first one to own one.

:lol:
Tcash

Thats a torque screwdriver. You can set torque by the angle method if you have the spec, but I don't think that is what that thing does, it's actually measuring torque, not angle.

Always wanted one.

Thu Apr 23, 2015 1:55 pm

Amskeptic wrote: raygreenwood wrote: Inspect your adjuster screw tips under at least a 10x loupe. Even moderate miles wears a flat spot with side ridges that are sharp. Turning the screw changes the aspect or angle of those riddges to the feeler blade giving a drag fell that may fool the user.

Yes, people should be punished for neglecting the advantages of frequent valve adjustments on preventing radical wear spots. Also, I like to blame the valve adjustment professional for pitting caused by dirty instruments.

raygreenwood wrote:
Also as I have stated numerous times.....most valves are two piece. Even the most perfectly made two piece valves have internal stresses that change the rate at which they expand...relative one valve to another.

Back in the .004" days, I could see where the above might have an effect on engine health, but when the factory increased the clearance by 50% in one fell swoop, I think there is a fudge factor with the Type 1 engines. Type 4 engines being designed with the .006" (.008" sodium), I follow without question.

I wonder to this day if I could get away with .004" on my 1600 if I was "conscientious". It has been a long long time since I have had to deal with pecked valve stems from too much impact forces, and it is why Chloe gets Porsche adjusters with the next set of heads, to wit: see below.

raygreenwood wrote: I also got away from the wear ridge issue with 911 adjuster screws.
Ray

Ah.....I didnt explain my point about the differences in valve expansion....and what bearing it has to why I adjust hot.

If you set them to .006" cold....assuming they all expand at the same rate.....when you check them hot with virtually every set of valves I have seen....you see at least one valve whose maximum warmed clearance is on average about .002" larger or smaller than the average of the others....which will usually be within a range Of +/- .0005" to each other.

Checking them hot several times after starting from cold will quickly reveal, which valve actually has a different expansion characteristic versus just a problem with your checking method.

I find much more accurate warmed up valve lash by setting them hot. I dont care what the lash is cold...because no one drives an engine cold for more than a few minutes.

I tested this with several sets of valves as well in the oven. Same result.

Typically I have found that in, winter, cool spring and early fall weather, the warmed up valve lash with all other engine temps in normal range....valve lash hot is .0025"-.003". In hot weather with oil and head temps at the top end of normal but nit, overheating.....hot valve lash is typically .002"- .0025".
Before I started adjusting them hot is was not uncommon to find abkut 2 valves out of 8 that are about .001"-.0015" of open lash left when warmed up and occasionally one that does not expand as fast.....that may be at .004"- .005" when all others are in the .0025"-.003" range.

Significant?.....maybe not with carbs or L-jet....but noticable with tuning of D-jet and highways speed driving. Ray

Thu Apr 23, 2015 2:19 pm

raygreenwood wrote: I find much more accurate warmed up valve lash by setting them hot. Ray
Your finger tips must be like leather?

Thu Apr 23, 2015 2:20 pm

raygreenwood wrote:
valve lash hot is .0025"-.003".
In hot weather lash is typically .002"- .0025".

Much as like the thought, sort of like adjusting your timing where the engine actually has to work, why not adjust the valves where they actually have to work? I friggen refuse to handle hot valves and smoky heat exchangers.

I've had to do it several times with customers who forgot to snug up a valve adjuster lock nut or a pushrod that suddenly found its pocket after the valve adjustment sort of a paTONK! CLACK CLACK CLACK CLACK CLACK . . . .

but I will not deal with that mess if i don't have to.
Colin