Still taps after valve adjustment?

[RSW]

I know there was a recent link on a very similar subject but the responce seemed to get side tracked once it was established that the cams had been reground.

My situation is:
I recently had the motor out of the and took the oppertunity to set the tappet gaps. I checked they with a dial gauge and I am confident the gaps are correct. (i did find some that had been slack)

When I started the car for the first time there was a tapping coming from what I thought to be 4,5 or 6 inlet valves. I took the cover off and checked again - making them a little tighter just to see if it would make any difference.

It didn't - the engine still taps. I don't believe the cams have been reground on this engine and all in all it seems in good order.
I do have 5w/40w oil in at present (just to warm up and drain) then I will be putting 10w/40w magnatec oil in. Could it be the oil is too thin?

I also noticed the rockers seemed to be what I would consider quite slack - they moved along their shaft easily (they had play in them) but I'm not sure if this is normal or could it incicate wear?

Could anybody give me an opinion on what the possible causes could be? The tap is considerably better then before the work - but it's not perfect - am I just being fussy?

Many Thanks
Richard

[Epster77]

I recently did a valve adjustment and I still hear a tap as well. I have been told that the sound is normal if it resembles a sewing machine. How loud is your tapping. Mine is only noticed when standing at the rear of the car.
Also, most everyone I know is using 20w 50 oil. You may want to give that a shot.
As for your rockers, they should have some play in them when you are adjusting the respective cylinder. There is a technical article on valve adjustment that should explain when there should be play in the rocker.

Hope this helps a little.

[RSW]

My tap is like a sewing machine I suppose, I could be noticing it just because I have done the work myself.

I had noticed the tap seems to go away when I raise the rev's slightly which made me think it was rocker shaft wear. However I was listening to it in a garage which does magnify the noise I guess.
If I have the boot closed I can hear the tap but only if I listen for it, it's not half as bad as it was before the adjustment.

I spoke to a local porsche mechanic prior to doing the work and he said he set them by feel of the rocker and simply checked them with a feeler gauge (but he'd been doing it for years) he also said as long as there is some wiggle on the rocker it should be OK. I set mine using a dial gauge to get the 0.10mm, but I found this was still open to judgement of how hard I pushed the rocker.

I just didn't want to find I had warn rockers or valve guides etc..
I'll give the thicker oil a go next time I change - I can see how this would make a difference.

Regards
RIchard

[john walker's workshop]

use a feeler gauge in the proper holding fixture. the dial gauge, as you noted, will change it's reading depending on how firmly you move the rocker up and down. now what kind of accurate measurement is that? about as accurate as the guys who "feel" the clearance. you are trying to measure against a spring, an oil film, and rocker shaft/bushing clearance. hard to get an accurate adjustment without actually stuffing a feeler gauge in there and creating the perfect drag on it.

[RSW]

Like I say, I have to be honest and say I set most of the gaps by dial gauge (I couldn't do the ones behind the pre silencer).

I re checked the inlet ones on the airbox side and I made them slightly tighter (after hearing the engine run for the first time) as I felt them to be too slightly too slack.

I could well have them all to look at again I suppose. THe problem is I am super cautious about setting them too tight.

Practice, practice..

[island911]

Originally posted by RSW
. . . THe problem is I am super cautious about setting them too tight.

That is the problem . . .if you want quiet valves.

Do as JWW says. He is spot-on. Use the feeler, snug them so the feeler drags (slightly) out; and you'll be happy with the results.

[Superman]

I sure hope I'm not disagreeing with JW here, but I like the dial indicator method. I have used the feeler gauges to check the results and I think I can use a dial indicator at least as accurately as a feeler gauge. The point of the dial indicator needs to be located with care against either the jam nut or the adjustor so that it will not fool you as they rocker rocks. you can see by playing with it how the rocker can be forced into a false reading. Again, paying close attention can result in accurate dial indicator adjustments, I think. I hope.

I have found that if the gap is outside spec (.004" +/- .001") then ticking will occur. I recently adjusted mine, and the engine is quiet as a mouse when cold, and at operating temperature it does sounds like a sewing machine. Just a little valve train noise, but nothing you would call "ticking."

BTW, while I have also been deathly afraid of adjusting them too tight, I think the danger might not be that awful. I think the valves still have a bunch of clearance at operating temperature. IN other words, I think you would have to be down to .002" of clearance, or less, in order to make the mistake of preventing the valve head from returning against the seat. So, .0033", for example, is safe. It is withing factory spec.

[RSW]

Interesting theory Superman - I too had heard that they could go a fraction tighter then 0.10mm (0.04") although I'm cerainly no expert on the topic.

I'd be interested in other views on the topic of going tighter then 0.10mm - possibly someone who has run there porsche on slighty tighter valves for a period of time.

Superman - where have you seen the "factory spec" for such valve settings? I'd be interested (reasured) if you could post or point to it if poss???

If that is the case I'd feel comforable in adjusting all mine to a "slightly grabby" feel on the swan neck 0.10mm blade.
The funny thing is it all boils down to the interpretation of terms as to what a "snug fit" actually is.

Richard

[tryan]

drag a screwdriver across a strong magnet. that is the 'feel'.

[Decolliber]

Originally posted by john walker's workshop
... stuffing a feeler gauge in there and creating the perfect drag on it.

What is "the perfect drag"? I often wonder this while doing a valve adjustment. Too tight is worse than too loose, right?

[Superman]

I can check my Spec Book when I get home, but I am absolutely confident that factory spec is allows +/- .001". No kidding, with the dial indicator, I can set them at .0035" or .0038" or whatever. I don't allow more gap than .0045" nor less than .0033" although my belief is that at .003" (the edge of factory spec), the engine would be quiet and all the valves would be returning to their seats for cooling.

I'll check the spec book tonite if Warren or somebody does not beat me to it.

[Superman]

Okay one more thing that other dial indicator guys will relate to but others may not. I find that I have to pry against the rocker fairly firmly to stretch the gap artificially, but the position of the rocker on its shaft makes a bigger difference. Once I have set the indicator to zero with the gap closed, I push on the back (cam end) of the rocker which raises the other end to .004". I then pull up against the adjustor end of the rocker to see if I am really at the top and to see if I can artificially over-open the gap. A good deal of pressure is needed to artificially widen the gap but......

The gap does change depending upon the wear on the rocker shafts and the position of the rocker on the shaft. At each position (closed gap or open gap) you need to slide the rocker back and forth because gap at one position is not the same as at the other end of the rocker shaft. Rocker shafts wear in a kitty-corner fashion, so the wear points at either end of the shaft are on opposite sides of the shafts, and at opposite ends. So, where do you do the measuring? I find that the gap you are looking to adjust to .004" is the TOTAL MAXIMUM gap. So, when you set the dial indicator to zero, you are at one end of the shaft, and when you open and measure the gap, the rocker should be moved to the other end of the shaft. If you don't include the extra rocker travel that is related to shaft wear, your valves will be too loose and they will tick.

[RSW]

Thank you - that would be grately appreciated.
I'm sure I gapped mine at 0.10 - 0.11+ using the dial gauge.

Thus i would guess these are on the slack side of perfect - hence the sewing machine noise.

I did note while setting them with a dial gauge that when I checked them with a feeler they where slacker then i'd expected them to be. I just assumed this to be correct.

Richard

[Gunter]

Here in the interior of B.C. , Canada, the average temperature is not as warm as California, so, I use 15W40 from Spring to Fall. In the U.K., I am sure the average temperature falls well between the temp. range given in the Porsche manual for 10W40. In California, or Arizona, etc. I would go with 20W50.
The valves will have a slight ticking unless you start having wear in the valve guide bushings or the lobes on the cams or the rocker shafts, etc. I did have a hard sounding tapping and found some guide bushings and wear on the cam lobes which had to be re-ground. I know someone who sets the clearance by turning the adjusting screw snug (0 clearance) then he backs off one tenth of a turn. (The pitch on the adusting screw is 1.0 mm) I prefer the feeler gauge. Get the Porsche tool P213 from Pelican, adjust the valves and go around twice to get out all slack. Always turn clockwise and blow out the dirt from the cylinder tops before you remove the plugs. Most people leave the plugs in. Cheers.

[island911]

Originally posted by Superman
Okay one more thing that other dial indicator guys will relate to but others may not. I find that I have to pry against the rocker fairly firmly to stretch the gap artificially,. . .

How firm is "fairly firmly"

See, this is why the feeler gage works so well.
For the most part, if you can pull the feeler gauge out of the gap, w/out cussing, they're not too tight.

[RSW]

Any feedback on the spec book Re: the 0.033 tappet gap Superman?

Regargs
Richard

[dickster]

When I started the car for the first time there was a tapping coming from what I thought to be 4,5 or 6 inlet valves. I took the cover off and checked again - making them a little tighter just to see if it would make any difference.

how did you measure the second time - not with a dial gauge?

someone said in another thread (jw?) - if it takes 2-3 wiggles of the feeler blade to remove it, thats about right.

thats how i did mine and they sound great.

you'll know if its tight 'cause it'll be a **&&^£%%£ to remove.

use the tool that was made for the job.

[RSW]

2 - 3 wiggles to remove, that sounds reasonable I can relate to that.
The second time I did them inlets was with the swan neck feeler gauge. I set then so they were tight'ish on that blade.

If I had to describe it I would say they were set so the feeler tool could not be easily moved with one finger - but required finger and thumb and the friction made the movement 'sticky' enough to make it difficult to slide that blade with out a little jerk as it first moved.

If that makes sence.

Richard

[Epster77]

Does anyone know the symptoms of valves that have been adjusted too tight?
Just curious.

[RSW]

when the engine gets up to temp the valves don't seat (they sit proud) and the combustion seeps past the valve head and the valves get burnt.