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SCAT Ratio rockers
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mikapen
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PostPosted: Sat Mar 10, 2007 10:36 pm    Post subject: SCAT Ratio rockers Reply with quote

1991 2.1 WBX engine. I bought this engine used with low miles, but one to two lifters became noisy. I adjusted them to 1 1/2 turns, but one lifter is noisy again. I will try driving with .006" lash for a week and see if everything pumps up again. But here's my question - the rockers are stamped SCAT, apparently replaced by P.O. How can I determine if they have a different, more aggressive ratio than stock? I don't like the different amount of threads exposed on the adjusters, and I wonder if I have too much rocker for the lifter or cam.
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PostPosted: Sun Mar 11, 2007 3:03 pm    Post subject: Reply with quote

Shouldn't be too hard to find out the lift ratio on those rockers. You need to measure from the shaft center to the adjuster center, and shaft center to the pushrod cup center. The latter will be the smaller dimension, and the former will be either 1.1, 1.25, or 1.4 times longer.
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mikapen
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PostPosted: Sun Jun 03, 2007 9:59 pm    Post subject: Reply with quote

Sorry for the delay in responding. My Scat's measure to be 1:1.25. I have adjusted the rockers to a GAP of .006" and driven for a long time to relieve what I think was "air-bound" condition, and it worked (so far).
I adjusted to a preload of 1/2 turn. All the lifters were so hard that the preload actually opened the valves for a while.
I used the 1/2 turn instead of 1 1/2 because of the ratio of the rockers and because the engine didn't seem as happy with 2 or 1 1/2 turns. The engine is VERY HAPPY now.
However, further inspection of the adjusting screws revealed lots of wear on the screw and the little ball-bearing spacer at the valve. The valve stem shows no wear.
The adjusters will need to be replaced. This explains why there were different amounts of threads exposed. But why did they wear? Improper installation / alignment / shimming? Oil flow? What's the right way to do this?
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tencentlife
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PostPosted: Mon Jun 04, 2007 10:19 am    Post subject: Reply with quote

It could have been a problem with geometry, they might have needed to be shimmed, but they might have worn unevenly due to no other reason than they were cheap. There are so many copies of ball-swivel adjusters on the market, and some of them are bound to be crap. I don't care for the ball-tipped type myself, because the ball can spin around inside the socket and expose a round face instead of the flat face that is supposed to stay in contact with the valve stem. Happily, your valve stems aren't damaged, so you can put in new adjusters and drive away happy.

I've had terrific success with the genuine Rhino-foot adjusters, but they only come in a 9mm screw. These are a swivel-foot, but turned inside-out. The ball is the tip of the screw; the socket is the "foot" that sits flat against the valve stem, and it's impossible for it to get turned around the wrong way like the ball-tipped kind can. You have to add the 0.060" spacers under the rocker bases with these, but that sets the geometry just right with stock heads, in my experience.

http://www.cbperformance.com/catalog.asp?ProductID=109

There are also the "Porsche style" adjusters, which are like the Rhino-feet but available in an 8mm screw. Spacers would probably also be needed with these. Your Scat rockers are probably drilled for 8mm (take out an adjusting screw and measure its thickness with a caliper), so you would want to use something like this:

http://www2.cip1.com/ProductDetails.asp?ProductCode=C13%2D4031

I have a set of those I'm about to try, so I can't yet vouch for their durability. They might be cheap, too. I can vouch for the Rhino-feet; I've got over 100k miles on a set with 1.25 rockers, and they are tough, no perceptible wear, and the valve stems remain perfect.

You don't have to use swivel adjusters (but I highly recommend you do); regular solid screw-type are OK, but they will wear the valve stems and themselves more than the swivels will. Just make sure to buy high-quality. There are a lot of cheap ones around that will mushroom in no time, or even break. GoWesty even had a problem with a run of bad adjusting screws.

I'm a real advocate of using 1.25 rockers on the wbx stock cam. It does add a nice little boost to power, especially with a freer-flowing 4into1 exhaust, one with some scavenging effect that is lacking in the stock 2into2into1 setup.

The 2 turns adjustment suggested in the book is a rough figure, and some claim that VW superceded that with 1.5 turns. It doesn't matter exactly how many turns you use, just as long as you have some preload on the lifter. I've always used 1.5 turns and left it at that, and I've never had any trouble with hydro lfters, other than the occasional rattling on startup that goes away as soon as the oil gets warm. 2 turns with 1.1 rockers gave about 1.8 mm preload in the lifter, as the adjusters have a 1mm thread pitch. Preload will be less with 1.25's, 1.6mm at the lifter with 2 turns of the adjuster. It's not that important how much, or even that they're all exactly the same. Just use a setting that gives 1 to 2 mm preload of the lifter, and the lifters will do the rest. Leaving no preload is OK temporarily, although I still don't see any point in it, but running for long with an airgap heightens the risk of a lifter popping out its circlip, which may get somewhere it shouldn't and cause damage. Also, once a circlip pops out, the guts of the lifter will pop out enough to take up the airgap, and in that position the lifter may leak oil, and then you're worse off than when you started.
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PostPosted: Mon Jun 04, 2007 11:54 am    Post subject: Reply with quote

there are a lot of mistakes in this thread.

1) Proper adjustment with hydraulics is 1/2 turn after 0 lash.

2) You should NEVER EVER EVER use swivel feet or 911 style adjusters with hydraulic lifters. These adjusters require valve lash to get oil into the ball. If you have no lash, you have no oil and they'll wear out very quickly.

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tencentlife
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PostPosted: Mon Jun 04, 2007 12:19 pm    Post subject: Reply with quote

We'll have to differ on both those points, John. I haven't used the 8mm Porsche-style adjusters yet, but as I said, I've used the Rhino-feet for over 100k mi. with hydro lifters and they're like new, and very kind to the valve stems. A very fine product. Splash-oiling and the swivelling seem to keep the joints well-lubricated. I hope the 8mm ones work as well, I'll be monitoring them to see.

Opinions about hydro preload settings are all over the map. Everyone has their favorite settings, and everyone claims their's work. Some can even present theories as to why their way works best. All I can say is my way has worked well for me. Take that for what it's worth. But please don't declare me in error simply because you don't agree with me.
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mikapen
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PostPosted: Mon Jun 04, 2007 9:41 pm    Post subject: Reply with quote

OK, there is a difference of opinion. Here's what I want to do.
I like the 1:1.25 rockers, so I want to retain them.
There was a discussion on a bay window forum about setting geometry - http://www.thesamba.com/vw/forum/viewtopic.php?t=168120
Any opinions about that procedure?

I believe my Scat rockers had Scat swivel adjusters. They're 8mm. These adjusters are through-drilled for oiling the balls. The oil passageway receives oil from the rocker through a circumferential groove in the screw. Two of these feet have broken off and one of the adjuster ends that receive the balls is worn @ 2mm. So it looks like this oiling idea doesn't work. It also looks like the adjusters are very cheaply made, so maybe the thing to take here is to avoid the cheap stuff.

I have to think about the swivel vs. solid adjuster issue. You both make good points. But I am concerned about the Scat rockers and their ability even to carry oil to their tips, and if they would even work with solid adjusters or non-Scat adjusters, for that matter.

Do I need to start over with new rockers if I want to use the 1:1.25?
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tencentlife
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PostPosted: Mon Jun 04, 2007 11:08 pm    Post subject: Reply with quote

Well. as I said, the ball adjusters you have may just be poor quality merchandise. Scat is considered pretty good stuff, but quality of aftermarket components can vary (as can OEM). You could certainly stick with that type. I personally don't care for them, especially with engines that have solid lifters and hence clearance at the valve stem. With a no-clearance application, like the wbx with hydro lifters, there isn't much chance of the balls getting turned around, since the flats are always engaged. My taste runs to the swivel-foot adjusters, as I've had excellent experience with them. I do prefer any type that has a swivel-tip, of whichever type, to a solid adjuster, as the solids flatten at the tip, and do the same to the valve stem over time.

I'm trying the Porsce-style swivel-feet I linked to, because I have a set of 1.25 rockers that have 8mm screwholes. The stock rockers on a wbx were switched to 9mm adusters, and there are 9mm-hole 1.25's available but at a higher price. If I were you, I'd use the 1.25's you already have, and get some good quality 8mm adjusters that you like. Then just check them after some miles to make sure they're holding up well.

Setting geometry is an inexact science, and isn't terribly critical anyway. Getting it right, or even close, will lessen some friction in the valvetrain, and minimize wear of the valve guides and adjusters. It's usually done on the bench, but you can set it up in the car thru trial and error. Basically, what you would like to do is have the rocker shafts set at a height from the head that causes the centerline of the adjuster to be as close as possible to alignment with the centerline of the valve stem when the valve is at half-open. That way, the swing of the adjuster has the smallest amount of angular deviation from the valve as possible when it is at its extremes of normal movement.

Using swivel adjusters of either type, rather than the stock screws, usually requires adding a shim under the rocker assemblies mounting blocks just to get clearance, as the foot can't be backed up into the rocker arm as far as a simple screw could be. How thick a shim depends on how large the foot is, and how far back into the rocker it can be backed before it binds, in the case of swivel-feet, or just can't be backed any further, in the case of the ball-swivels type you already have. Alternatively, shorter pushrods can be used to remedy that problem, or grinding the bottom of the rocker tip. I've found that a 0.060" shim just gets me clearance with the Rhino-feet, and happens to put the rocker shafts at just about the right height. The best geometry may involve a combination of shims and pushrods.

Getting geometry dead-on with a wbx is a bit harder because the stock cam has different lift values for intake and exhaust. The best setting is going to be a compromise between them.

You can use a procedure like the one the fellow explained in the thread you linked to check geometry, but it's best to have a dial indicator to set up against the valve spring retainer surface so you can measure and hold the valve at half-lift. Make sure the lifters are solid, not spongy, on the valves you check, or the valve may change position while you're checking.
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Wellington
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PostPosted: Tue Jun 05, 2007 5:01 am    Post subject: Reply with quote

how about using these:
http://www.cip1.ca/ProductDetails.asp?ProductCode=C15%2D20196
no swivel feet to worry about.
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tencentlife
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PostPosted: Tue Jun 05, 2007 8:43 pm    Post subject: Reply with quote

I guess I still like the adjuster on the valve end. I'm not in love with lashcaps. Personal taste. But they work for lots of folks, so why not?
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PostPosted: Wed Jun 06, 2007 9:26 pm    Post subject: Reply with quote

This is from CIP1.com=
Special note: When using any high-ratio rocker arms, stock length push rods will not work. You will need to purchase a set of CUT-TO-LENGTH heavy-duty push rods. The length required for any engine is impossible to know until you test assemble your long block and calculate the length required to achieve the correct rocker geometry based on your engine combination.

Would I need to get special pushrods to use the 1:1.25 rockers or not?
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PostPosted: Wed Jun 06, 2007 9:35 pm    Post subject: Reply with quote

No. The shims will do it if you use swivel feet at the valve end, no shims at all if you use regular screw adjusters. Even so, you may want to shim those to get the geometry better. I haven't used the other rockers with socket adjusters at the pushrod end, so I can't say.
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mikapen
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PostPosted: Wed Jun 06, 2007 9:53 pm    Post subject: Reply with quote

I'm pretty sure that when they say "high ratio" they mean higher than 1.25, such as their 1.4 rockers. Scout around on their website and see if you don't agree.
Gene Berg says 1.25 rockers should work with stock length pushrods, too. You might also need a milder cam for 1.4 rockers.
See above, tencentlife says .060 shims worked for his 9mm rhinofeet, but the final shim thickness for a different product would have to be determined at final installation.
Some say that grinding the rocker instead of shimming will give enough clearance, but you still need to be confident with the geometry to rule out shorter pushrods.
I am about to embark on the "new adjusters in my Scat 1.25 rockers" journey, so I will report. It will be a week or three before I get it all together, though.
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PostPosted: Thu Jun 07, 2007 10:36 am    Post subject: Reply with quote

Yes, my last comment was directly in reponse to the question,which was about 1.25's. When you get into 1.4's, it's a whole 'nother ball of wax. In every case, whether shims alone will work or different pushrods will be needed as well depends on your choice of rocker type, ratio, the use of lashcaps with pushrod-end adjustment, or the use of swivel-types vs. standard adjusting screws with valve-end adjustment. Many variables, no pat answers, you figure out what's needed as you go.
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PostPosted: Thu Jun 07, 2007 1:00 pm    Post subject: Reply with quote

This thread may be helpful for understanding valve geometry:

http://www.thesamba.com/vw/forum/viewtopic.php?p=1304981&highlight=zero+lift#1304981
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mikapen
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PostPosted: Tue Sep 11, 2007 8:38 pm    Post subject: SCAT Ratio rockers Reply with quote

Here is an update on my situation. I bought these 8mm elephant feet adjusters: www.cbperformance.com/catalog.asp?ProductID=1411
I used a dial indicator to set the geometry and found that the .060 shims provided were right on. I also found that the P.Owner installed .120 shims and set the geometry WAY off, explaining the failure of the SCAT ball-end adjusters. I liked the look and feel of the swivel feet and continued.
I think I should have ground .060 off the bottom of the rocker tip to allow the "feet" to retract further. As it was, I had to set the adjusters at contact plus 1.5 turns just to get clearance for the swiveling. My engine is happier with 1.0 turn from contact. After a couple hundred miles, everything looks good in there, and the adjusters are oiling well.
NEXT QUESTION: This engine came with big finned aluminum rocker covers that didn't seal very well, so I also bought a new pair of deep covers. Unfortunately, they were identical Taiwanese pieces, and they don't seal well, either.
I have never had trouble getting my valve covers to seal. I have always used the cork/rubber stock gaskets with gasket sealer only on the valve cover side, oiling the "head" side. This is not working, and I also tried some all rubber Fel-Pro gaskets that also leak.
What is a good solution for my leaky valve cover seals? I think the aluminum covers are heavier than stock, and the bails don't hold them tight enough. And I don't think stock covers will clear the ratio rockers. Suggestions, please.


Last edited by mikapen on Wed Sep 12, 2007 6:23 pm; edited 1 time in total
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PostPosted: Tue Sep 11, 2007 9:09 pm    Post subject: Reply with quote

Stock covers usually clear even 1.4's. Give it a try. Put them on without gaskets and turn the motor thru a complete cycle and see if they bump or mark the covers. If they don't, you'll have at least a gasket's thickness of clearance, and that would be plenty.
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