ShopTalk Forums | Aircooled VW Tech & Restoration Help

Plastermaster....in a certain respect, you are right. At my age and with all the years I have been working on my own stuff, I just learned this 4 years ago from my brother. Basically he said....if you have a new cam, whose actual TDC markings are not known to you and you want to find position for valve adjustment that is "safe" enough at least to start with.....rotate the engine while watching the valves from undeneath (wheel method). When the intake valve just starts to close from full lift...adjust the exhaust. When the exhaust just starts to open from full base circle closed...adjust the intake. It works like 90+% if the time . I'm qouting from memory......because I had to write that down. I don't adjust that way....but it taught me a lot. The problem with just finding the spot on the cam....that gives the most gap at the valve adjuster tip, is that this is the very lowest spot in the base circle.
Try adjusting it there. Then crank that piston around to actual TDC. What you will see.....is that the valve at TDC....is now lifted by between .003 and .005".....give or take. This is the problem with adjusting it to the lowest point...as I mentioned in my last post. My whole point about mentioning this "extra"...little known portion of slack in the valve train...is that there is clearance built in (on most cams). That will keep you from getting in a sbind that will bend the valves from valve train interference (different than striking a piston to be sure). Hydraulic cams...I don't know about.
But this extra slack....is there, to be sure that at the TDC firing point....the valve is fully closed.
In a perfect, perfect ,perfect world.....once the valve is fully seated...if we could calculate the perfect expansion rate for warmed up....there would be no need for any slack between the adjusting screw and the valve stem tip, once the valve is seated at TDC firing point. Just a dead fit. But the world is not perfect...and we cannot calculate for that exactly . But neither is the VW world "uniform". The engineers gave us an across the board number... .006"...that "should" cover all eventualities and allow the requisite... enough slack to be safe. Wether its due to new and better materials...or what....I don't know, but I have been finding that this amount of engineered in slack, is not only slightly excessive on some engine combination, it is nowhere near even when everything is warmed up. It does not matter the actual cause of this.... because, for the sake of arugment ...it could be that cylinder cooling more or less, differences in parts, differences in quality of construction....whatever the cause....... It exists.
Yes, when adjusted this way... the valves run much quieter, and have less valve stem and tip wear....and throttle repsonse on the stock FI is improved. But...as I noted....a good amount of studious checking/driving is needed before you decide a particular valve needs further adjusting and what it should be adjusted to.

Bajaporsche

As for making valve adjustment harder..... ...how so? I use the same tools....3 feeler gauges....a 13mm box end wrench...a 1/4" drive ratchet and 13mm socket...and a screw driver. I generally adjust them cold to achieve the spec I have found they will grow to....hot. There is only the occasional valve that I adjust actually hot. This is because the difference in what it grows to, is a different enough and subtle enough amount, as compered to the other valves ....that I rarely get it exactly right by adjusting cold, to reach a certain hot value. I hope to not have any valves or parts like that...when this new engine is finished. As noted, once you get this together..you can do all of your adjusting cold...and all of the final checking....hot. By the way...as noted below..I did fix that.

Generally...I do not have any really alien valve adjustments. They may read like.....006". .006", .005", .006", .0045", .006", .004". The lowest I have ever had...was .0035" cold. It left .0015-.002 when very hot. I got rid of that........by changing out the pushrod . For whatever reason, that pushrod had a different growth rate. Like I said...its not all in the valves themselves. I would also suggest, taht is you have a whole slew of pushrods....before you select 8...again measure them with a jig one by one, heat them uniformly in an oven..and quickly slap them back into the jig. It may be nice to not only select them by correct length, but uniform growth rate. I have found....there are differences from lot to lot. Some will say...."yes...but thats not really significant"....dang! we are talking thousandths here arn't we?

How do I get these .0005" readings? I buy cheap sets of feeler gauges and lap a larger one down..check it with a good micrometer. I keep them in the glove box...marked...in a rust free bag.

I also find, that when there is less extraneous gap.....there is less hammering of the adjuster tip...even with 911 style adjusters. The parts wear less. Every oil change is a valve adjustment. Once I started setting these up this way....I rarely have to adjust anything more than .0005".

How to make life easier underneath the car? Whatever cam you have, find your exact TDC points...by hook...crook...mirror...stick trick in the plug hole...dial indicator...whatever.
Before you start this...drill a small hole in each side of the bell housing....like at 5 o'clock and at 8 o'clock. Maybe 3/8" inch each...or even a notch at the bell housing egde. Then scribe a line throgh the center of that hole....so the hole looks like a "0" with a line through it. Now with a centerpunch the diameter of the hole.....which is why I suggested 3/8".....put a nice precise punchmark on the egde of the flywheel. Then mark the punchmark through the flywheel with a different colored fine point sharpy for each cylinder TDC. I don't have to tell you to keep track . Then (you should wait for the engine to need to come out for this).....take the flywheel out...engrave nice sharp clean lines for these marks, fill them with white enamel, drop into the local machine shop and borrow their letter punch set (1/8" preferably)...and put a cylinder umber next to each one. I have short rubber stoppers in my bell housing holes.
This way...when you are under each side of the car...you pull the plug...get your flashlight...orient your head to line up your eye correctly with the slash mark on the outside of the bell housing.....and turn the wheel until a mark comes into view.....now adjust. Remember..that if you turn the engine in reverse...you can adjust intake and exhaust together at one time....in order...for cylinders 1, then 2,...then move to the other side...then 3, then 4. Ray

have to say all this gives me more appreciation for hydraulic lifters on a stock or near stock setup even with their limitations. don't understand why we haven't had more r&d in this department.solids seem so archaic to me even on a vw. besides i'm too old to be contorting under there every month.

I won't get into the hydraulic argument. There is something to be said for them, in that they do keep "0" tolerance ...technically...at TDC because there is some give in them.
But...My reservations are precisley because this "give" exists. They definately lose power on the stock injection systems. Partly because, their total amount of lift is likely to be different from valve to valve...wether due to variations in oil pressure and fill state of the chamber in them...or more likely to variations in manufacturing tolerance or...as we are speaking about here and the most common problem I find......variations in how each of the several parts inside these lifters, change tolerances when heated up. They are seuccesful especially in watercooled cars...because there is less upper end heat, less variation in the oil pressure...(a lot of head designs in watercooled are especially designed with hydraulics in mind from the start where as ours are not)...and in the case of the v-8....the cam ramps in most WC cars aree much less sharp with rates much lower thn ours. In other words...in the average VW...losing a very small amount of lift or duration makes a much larger impact. That variation may not exist in many v-8's with their cam designs...and would hardly be noticed. Ray

ray you amaze me as usual.still seems these design flaws could be engineered out . what i would love to see is something along the lines of the new" jack raby super hydraulic lifter" yeah i know dream on

Plastermaster wrote:It seems to me if you have a non stock application (non stock cam timing) that the "turn the wheel" method would be best. Right?
Ron

I agree!

Wally wrote:

Plastermaster wrote:It seems to me if you have a non stock application (non stock cam timing) that the "turn the wheel" method would be best. Right?
Ron

I agree!

But, as Ray clarified, you still need to find TDC and set your valves there and NOT at the bottom of the cam. Hopefully on the engine Jake is building for me, he will be able to let me know the idiosyncracies of the valve adjustment for that particular engine so I will have it as a base line. It would sure make it easier.

Ron

from Ray
As for making valve adjustment harder..... ...how so? I use the same tools....3 feeler gauges....a 13mm box end wrench...a 1/4" drive ratchet and 13mm socket...and a screw driver. I generally adjust them cold to achieve the spec I have found they will grow to....hot.

from BajaPorsche
well, I just use a 14mm box wrench and a screw driver, and feeler guage.
I lift one wheel get underneath plop off both valve covers....turn the wheel til...lets say #4 exh valve is fully open, then I set the #2 exh valve... usually two valves are compressed at a time....

All I know is that the top of the lobe is opening one side, so the other side must be at the bottom of the lobe...
I've seen reports that suggest this way, and others have told me it works....
for me, i don't have to get back out from underneath, check for TDC markings, slip back underneath, and set two valves on the same cylinder...... it just makes it so much easier...and I guess I get lazy!

But I don't know about split duration cams or any other ones...
but the reasoning behind all your points Ray make a whole lot of sense.....
and now I'm scratching my head.

Yes it works. But....and you need to check this for yourself to really understand......if you set valves this way....meaning turning the wheel in high gear, engine going backwards, while watching both valves of one cylinder rise toward fully closed..........when they reach the fully closed point.....they are NOT at the bottom of the base circle, and the valves on the opposite side of the engine are NOT at full lift.

The best way to experience this.....is to use a dial indicator on the valve spring retainer. Stop moving the wheel andengine the second the dial indicator says that the spring has stopped movng outward. Note the number of thousands the dial has moved. Now...wiggle rocker arm.....gap?...or no gap? Usually you will have maybe .001-.002 at this point. Have someone watching up top with a flashlight to tell you if you have reached the TDC marke yet...which you have not. If your valves were adjusted properly.....by the time you reach TDC by the marks up top...your gap via feeler gauge at the rocker arm should approach .006. Done?....no. Keep turning past TDC. The gap at the valve will increase.

Your standard adjustment point is actually on the lower flanks of the cam ramp right before the start of the minimum base circle.

But...just adjusting them by turning the wheel until the valves have reached the top and quit moving......will certainly be safe....as it will leave you with a noisey valve train with extra slack in it. If you adjust valves by turning the wheel until the largest gap is produced at the rocker....which is truely the bottom of the base circle....it will certainly be quiet, but you als risk having manifold detonations if the design oif your cam starts ignition at ctual standard TDC.,...becausethe valve will still be at about .001-.003 lift. Also....its risky though its quiet, because if you are off in your adjustment, you have taken out absolutely all of the slak by adjusting at the true bottom of the base circle. If your adjustment there is too tight...you will actually prop the valve open or bend a pushrod. Ray

from Ray
if you set valves this way....meaning turning the wheel in high gear, engine going backwards, while watching both valves of one cylinder rise toward fully closed..........when they reach the fully closed point.....they are NOT at the bottom of the base circle, and the valves on the opposite side of the engine are NOT at full lift.

from Bajaporsche
How about if I set them like this
I turn the wheel until I see only 2 valves let's say #2 exhaust and the #3 intake....when those valves are fully open, rocker arm is fully engaged, the high end of the cam is moving the pushrod in those two directions........then it seems that on the opposite end of the cam is the lowest cooling point... the opposite end of the #2 exhaust, is the #4 exhaust...the opposite end of the #3 intake is the #1 intake...seems that if the same cam lobe opens the #3 intake, and the same cam lobe opens the #1 intake......that once the #1 intake is open, then the #3 has to be fully closed..... does that make any sense.......
I just turn the wheel till two valves open on different cylinders, then adjust the oppossing cylinder same valve...be it intake or exhaust.....
do you think that will work.......my engine runs quieter, but maybe too quiet?
Turn until Rocking: Adjust:
#2 Ex & #3 In #4 Ex & #1 In
#1 Ex & #2 In #3 Ex & #4 In
#4 Ex & #1 In #2 Ex & #3 In
#3 Ex & #4 In #1 Ex & #2 In

Yes...it makes sense...but what you are confusing...is that the fully closed points of the valves...that being when the valve rests fully on the seat........is NOT at the full bottom of the base circle, the first instant it touches down. At that instant...there is no valve gap....yet. Keep rotating the cam further...and the gap (when cold)...will appear out to .006". You are still not on the base circle yet...you are just a ways up the flank from the base circle. A bit more rotation...and the valve gap grows. You are now on the base circle. Since its a small diameter, you are only there for an instant...time wise, before the valve gap starts shrinking as the lifter travels up the opposite flank. Depending on the cam, its about 1/3-1/2 more camshaft rotation.

Now...on the other valve, it may be very close to full lift...but, unless you are dead center in the middle of the base circle radius on the opposite closed valve....you will not be at full lift on the other.

If you want to find out where the middle of your base circle really is and where the flanks end, .....on the closed valve, set it to the best of your ability at TDC... and set the gap to "0" lash. Now keep turning slowly. The gap that was "0" lash...will start growing. You may see it grow to perhaps .004". At the very degree...at which it stops growing....is when you have entered the base circle. Mark that on the fan just for reference...and on the dizzy acording to the rotor position. Keep turning. This gap will stay the same all the way through the base circle...until you reach the beginning of the other flank. Then it will start shrinking. Mark and record the instant it does this. You have moved through the base circle and are on the start of the opposite flank.

Now look at the range of degrees of movement on the distributor...its large....and on the crank pulley...its HUGE!. Its larger than you thought! If...at the same time you are doing this...you put a dial indicator on the opposite valve that is opening.....you will find the point of highest lift.....right dead center opposite the center of the base circle....and due to the "pointiness" of our cam lobes...quite a good deal different amount of lift in correlation to where the base circle started opposite and the flank ended....as the lifting valve falls over that sharp nose. Very different dynamic from side to side. Nice stuff to know...but you will mess it up...trying to set a closed valve gap , by judging what the lifting valve is doing.

The whole point of all of this...is simply to realize that there is more in the cam lifter cycle than meets the eye.
Valve closed...is not the lowest point on the cam. Whatever you set your valves at.....the valve itself on intake, must be seated and closed tightly when the piston reaches TDC. It was designed this way with the ignition and compression in mind. The intakes valves actually close before the pistons starts back up. The extra slack we are speaking of is actually there while the piston is traveling up and compressing. But is already disappering when ignition happens. You do not want to lose the gap between the adjusting screw and stem tip too soon....or there will be valve movement before the power stroke is complete. this is why the stock TDC points must be paid attention to. Yes, it is different on non-stock cams....but the premise is the same. Everyone should map their cams this way. Though it seems no big deal to have a couple thousandths extra slack in the train.....its large....because the amount of cam rotation needed to change .001" is larger than you think..........AND....the amount of crank rotation is TWICE that of the cam. Closing an intake valve .002" too soon or too late into a powerstroke is bad for power. Closing or opening .002" too early or late into the exhaust stroke...is equally bad . It can be quite a number of degrees of crank rotation for those .002". It can cost you power...and make heat. Ray

I like Ray's valve adjusting method. Its a litttle tedious for me to do every time however.

I normally do that type of adjustment the first time I fire up the engine and up until the point that the valve train "settles down" and quits changing adjustment as frequently. Here is the method I use, for what its worth:

1) Rotate engine until the #3 cyl valves are in "transistion". This is the point where both valves start to rock from open to closed on on #3 cyl at the same time.

Now you know you are at TDC on number one.

2) Double check you are at TDC on #1 by wiggling the rockers while slightly rotating the engine each direction.... is the rockers at their losest point? Now line it up with TDC to be sure. This will also help you determine where TDC is on each cylinder if you have a split duration cam. (163/86b myself)

3) Adjust #1 valves. They will both be closed.

4) Rotate engine Counter-Clockwise until the next cylinder has both valves at their free lash, closed point. This should be about 90 Degrees from where you started. Make sure, rock the rockers. On funky camshaft grinds your opening and closing points will be different than a standard cam's points.

5) If you adjust everything to .006" you'll be safe...after the engine settles down, I generally tighten it to .005" unless I feel a power loss or if the engine "sounds" tight...I guess it comes with time.

The reason I don't adjust to TRUE TDC on each cylinder is because I've found that my lash can open up as much as 1/8 Inch when its showing .006" at TDC...I don't know why, its really weird.

What do you think Ray?

Aha!...what cam are you running Bobby? You are seeing the effect I have been describing, but your timing is just different than mine. What is happening, is that at piston TDC the difference in where the lifter is contacting the cam...is a long way up the ramp from where the base circle actually starts. In other words..it appears that your valve closes pretty early.

My adjusting method takes about 10-15 minutes total. Its actually pretty normal. That is because I found my adjusting points while and marked them on the flywheel and fan. I just turn to the mark...adjust a pair of valves. The hot checking comes later. Since I had already found my variance from normal by hot checking earlier, I simply adjust that value in at the cold setting and check the corrrectness when hot. Since I turn the engine so the rotor turns backward....I am able to adjust both valves on each cylinder in sequence.....but the mark for each one is just a hair off....so there are actually one turn to a ,ark adjust intake...turn a lsiggt bit more and asjust exhaust...then turn to the next main mark,,,,adjust intake ...turn a little more adjust exhaust etc. In order...1,2,3,4. Ray

I am glad to have generated this much fuss. This must be the shoptalkforums equivilent to the McLaughlin Group!!

So, I take it that leaving the setting at .006 is OK, but the purist POV would be to stop and check hot, record, check again, then adjust to the "cold" valve based in this info.

If I were to drive this bus 3100 (one way) with the valves set to .006, would I be OK? Going west via Route 66 from Chicago to LA, trying to avoid large mountain passes. How about under 600lbs load (weight includes me)?

Oh yeah. This whole thing was not about the stock valve clearances being wrong...its about having more clearance than is necessary for the individual engine and materials it is made of. Not that its necesarily a bad thing having too much slack,,,just that there are benefits to having it more correct. Just adjust your valves like normal. Ray

from Schnyde
I am glad to have generated this much fuss. This must be the shoptalkforums equivilent to the McLaughlin Group!!

from bajaporsche
and Ray is Mcglaughlin... seems Ray know alot more about these engines then me...... and I like his reasoning for his methods.... some XLNT theories he has.

But I think it boils down to, after the valves are set, in about 500 miles, the gaps have changed maybe.0005..... that's a half of 1/1000's and I think they usually get tighter? Ray will know more about that then me..... (and I will learn more interesting info from him)

from Bobby74
The reason I don't adjust to TRUE TDC on each cylinder is because I've found that my lash can open up as much as 1/8 Inch when its showing .006" at TDC...I don't know why, its really weird.

This is the exact reason why I do my valves the way I do..... I tried to set them at TDC before....and they would always be noisy..... then after about 30K I couldn't hold an adjustment...... I was seeing about 1/8, to 1/4 inch clearance..... had to adjust it to where, I couldn't adjust no more..... rocker screw all the way in..........
Pulled the lifter out, and it had ground down past the level mark and into the void (I'll send a picture if anyone wants to see it) amazing that it still ran with all that metal in the engine......
well, I slapped a core lifter in, and drove it another 35K until it dropped a valve, on the other head........
But I think I had set the valves, and got so much play in it, that it banged the lifter until the finish was gone, and ground it till the void (hollow section inside lifter)
So for me, just to be safe... I do it the way I do...... technically it's probably wrong, but for me, it's the safest option to making a mistake---AGAIN!