Inside the case: building for reliability

Please do -- I'm running into a confusion block. I need pictures.

I am curious to know how much oil flows through each rocker assembly and into the upper head area. Drips? Squirts? ...

One article (can't remember source) mentioned an engine with a modified cover(s) that showed oil almost filling up the cavity when revved hard for a sustained period.

Obviously, there would be a big difference from a stock engine to the larger modified versions and the choice of rings, used vs new case, the rocker shafts/arms/adjusters, etc, all would have a bearing on the outcome. Some engines puke a lot of pressure into the case and if the valve covers are vented, I can see the flow of blowby gasses maybe holding the oil from running down the pushrod tubes.

My 1600 has almost no blowby compared to the 1776 I build some years back. Maybe blowby pressure and volume is an indication of the engine efficiency/condition.

RT

I was mistaken -- there is some room to push the follower out farther. My W100 has about .082 between the lobe and the follower when the latter is all the way out. Shoved some feeler gauges in there. More clearance than that is required, of course, to avoid collision.

Not sure how to measure the base circle, but with my W100, measuring across the lobe at right angles to the high point, I get 1.17''

This means the follower is sitting .030 (if I measured the right thing and you and I measured the same thing and you didn't round off during units conversion too much) closer inward. This is the position that the intake follower is in when oil is routed around it to the exhaust follower's bore. The stock groove is only .110 wide, so while a .030 offset is not exactly a bottleneck, every little bit helps.

This illustrates that it would be wise to check the base circle diameter of any aftermarket cam. Unless the oil transfer groove is modified so it rests over the oil port in the new resting position, a cam with a significantly smaller base circle will cause your exhaust rocker to not get oiled.

But regardless, more lift does me no good because high rpms are not what the Wonderbus is all about, it won't change my volumetric efficiency a bit, while it will add additional strain on the valve train.

Which is a grand idea and one I plan to implement. I understand the HVX mods cover a lot of ground and I'm poking around the 'net looking for what information I can find about all of them.

On Tue, 22 Jun 2004 10:27:50 -0700, "Mike Rocket J. Squirrel Elliott" scribbled this interesting note:

Bob Hoover mentioned this a while back and I thought it might come in handy as a reference, so here it is:

I haven't read it yet, but it seems to me that everything you want to know has been mentioned somewhere. This is a good place to look as well.

I like reading all the answers to your questions. They keep the pot stirred up a bit and that's a good thing.

-- John Willis (Remove the Primes before e-mailing me)

On the contrary, you will appreciate the increased *torque* that the higher lift offers you.

Rule of thumb: Lift = more torque throughout the existing rpm range Duration = more horsepower, but it occurs higher in the rpm range

The W100 is a "torque" cam, the best choice for near stock off road vehicles or heavy buses.

You already have increased displacement, the mild torquey cam would allow you to take the most out of it. Without needing to rev it any higher than you did before.

And I wouldn't worry one bit about added strain on valvetrain components.. that really is a MILD, tame cam. Not even a street cam, just a little helper. No need for heavy duty special springs or anything. You won't be revving the engine any higher than before to get it moving, quite the contrary. You just get more basic power in the low/mid range. Don't sweat it.

I'd run it without thinking twice, and I recommend it to any bus owners who bring them to me for a rebuild. No other "tricks" or special parts are needed, the rest of the engine may remain bone stock. The impact it has on longevity, wear, driveability etc. is marginal, non existant, or even positive. Forget everything you ever heard about "high performance cams". You don't have one.

If I knew your engine was built by someone who knew what he was doing, I'd say you don't even need to re-jet the carbs to get everything tuned just right. (Assuming you live roughly at the same altitude where the engine was tuned in) But the way things are... lol.. no matter what you put in there, you'll have to spend a while with jetting and tuning. Yes, even if you try to use a stock carb and cam.

You have all the components for a sweet reliable engine, tested and true, easy combo. Others would pay good money to get where you are. All you need to do is wrap it up properly. :)

Jan

Read this book. It's full of good advise for anyone building any aircooled VW engine, stock or otherwise:

How to Hotrod Volkswagen Engines by Bill Fisher published by H. P. Books, Tucson, AZ, 1970 ISBN 0-912656-03-4 (excellent book, well written and researched)

No resurfacing should be necessary.

IMHO, the best investments you can make are: case savers, full flow filtering, counterweighted crank, swivel foot valve adjusters.

Get Berg to weld counterweights on it instead.

Probably a good idea. Get an OLD used cam still in good condition for the most reliable part.

Yes, OE VW. Be careful here.

Yes, they're all good quality.

Rimco can rebuild them

Berg kit for full flow.

Not sure what you mean, but you're not doing the engine any favors if you lug it. It is much happier at medium RPM. I like the balancing that Berg does.

Lots, probably. Don't try to get all the "latest" hot parts. Do read the good book above. Berg has good papers on a lot of topics. Don't forget possible head work (not yours, the VWs ;-).

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----------------------------------------------- Jim Adney snipped-for-privacy@vwtype3.org Madison, WI 53711 USA

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This would mean each cam grinder would have to offer a range of specially fabricated lifters to match their cams.

I've never heard of any that do this. Can you point us toward a manufacturer that does?

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Don't you find it odd that the Type IV and ALL modern OHV engines provide full-time lubrication to the rocker arms?

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Which is also saying that a higher lift cam WILL affect the operation of the stock system when those conditions are NOT met... which is virtually any time you use stock lifters with an after-market cam.

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I wonder why this doesn't happen. Modern engines all use 100% valve-train lubrication and they manage to escape the problems you mention. Indeed, when converting the Type I to 100% valve train lubrication I've found them to run cooler and to last longer.

-Bob Hoover

I've made some illustrations, I hope to clarify things up.

In the following picture, you can see that oil is fed from the center (inlet) lifters towards the outer (exhaust). The lifters are shown in different locations, to show how oil flow is directed in the stock T1 engine case. The relationship of the lifter positions between different cylinders is arbitrary.

You can see from the above drawing, that the lubrication of each cylinder lifter pair (in/ex) is unrelated to the position of the lifters of the other cylinders.

This is an animation showing the actual movement for the pair of lifters for #1 cylinder. The timing follows a typical cam. The oil flow is shown in orange color.

Bill, '67 Bug

Performance cam lifters have larger and deeper grooves. This way there is more margin for the oiling holes to line up. This is a picture of a aftermarket lifter (left) and an original VW lifter (right) showing the differences.

The type IV is designed from the factory to operate with full time lubrication. The T1 isn't. You may be fixing a problem and creating a series of other problems that you then have to fix too, in order to work properlly. Modern engines need full time lubrication, to lube the cam which is on the head, it's not a 1 to 1 comparison with the T1. Just because G. Berg did this modification to some of his engines doesn't mean that this is the way to go for every engine assembled. Anyway, I've never seen a stock rocker arm bore so much worn that it would need replacement, when using a stock or mild cam. If connecting the top and bottom grooves is a tried and trued modification then why don't we find lifters allready modified this way in the market?

Bill, '67 Bug.

The picture also shows how the head of the performance lifter is more flat, allowing it to enter deeper into the case.

Jan

Great pictures, thanks.

That they are. If I said something about that earlier, I meant the neighbor lifter, not cylinder, being starved for oil, when the center lifter (Intake) hole/groove don't match. My bad if that was the case.

Your picture explains it beautifully. That's what it looks like in a torn down case.

Gorgeous animation, did you verify that the cam opening sequence for each lobe is as pictured? I'm too groggy to focus on that, can't concentrate.

Anyway, the animation shows how a stock cam would operate. Now do another one with a reduced base circle, (lifters would fall in deeper into the case, closer to cam) stock lifters, and more lift that stock. (Lifters would travel up further into their bores, away from cam). You can add duration too but that's almost irrelevant.

..if I may ask :)

Beautiful work.

Jan

Thanx. The cam lobe movements are probably not accurate, but the movement of the followers is. The animation begins after the spark. Then the Ex. valve opens, then closes, and the In. valve begins to open with a bit of overlap. The In. valve continues to open while the Ex. valve stays closed. Then the In. Valve closes and during the most of the compresion stoke and the expansion stroke, both valves stay closed.

That's why you need the performance lifters with a performance cam, so that the wider grooves still line up with the oil holes in the case, or you have to machine your lifters to widen the grooves appropriatelly.

By the way, I think (I'm not 100% sure, I'll have to double check on that) that most performance cams have the same base circle (heel of the cam) as the stock cam, if they are ground on new blanks, with the exception of high lift cams. Cams based on reground stock cams have a reduced base circle radius, to give additional lift.

Bill, '67 Bug.

Gene Bergs modification called for a diagonal groove (about 45 degree angle) .010 to .020" both deep and wide. That would be pretty easy to do with a Dremel and the fine cut-off wheel. He even lists a part number of a set already modified (GB 325M) but I don't know if they still offer them. He talks about new cases having the oil feed holes drilled off center and/or large base circle cams causing the oil holes to be out of line. Not sure if that reasoning still holds true - the information is pretty old.

Anyhow, I've pulled old lifters out of a case and usually always find the bores tight. But that doesn't surprise me. Even if the oil flow was severely reduced, there would probably be enough to keep that film of oil in the lifters. What would suffer is the other end; the rockers/adjusters.

That's it! I've gotta get an old V/C and modify it with a window. Just for testing purposes. I'm curious...

RT

Got it, plan to read it cover-to-cover on upcoming bicycle ride up coast of NC (ilambert -- you're from thereabouts, yes?)

Counterweighing vs. grinding and getting the whole shebang balanced at Rimco. This is a Whole New Topic for me -- can you explain a little more for my and anyone else who is following this thread?

Anyone got one for sale?

What kind of messy things can happen otherwise?

That works okay?

Er, lugger as in slug-like bus, not vroom-vroom performance buggy. No lugging here.

Check, check, check, and thanks for advice but will check my head for needed work anyway.

I second this request. The whole issue of how aftermarket cams affect the oil getting to the pushrods deeply interested me.

This has me a bit puzzled. Even at 3,000 rpm, cruising down Highway 1, I can't imagine that the Wonderbus's engine is being starved for fuel/air or having a hard time getting rid of exhaust gases. So I don't see how higher lift buys me anything (I am very ignorant of all this, so further explanation would be very appreciated).

As I understand it, there is nothing to be gained from opening a valve past 1/4th its diameter.

I read at

that,"The effect of [the constriction of the valve] shows up as a pressure drop through the intake valve. So why don't we just open the intake valve further? Because when the valve is lifted a distance equal to 1/4 its diameter, the area of a cylinder around the valve (that the fuel/air charge passes through, not the engine cylinder) is equal to the area of the valve face and intake port (ignoring the valve stem). . . Experimentally, the amount of additional flow through the intake port increases very slowly as the lift of the valve increases beyond 1/4 of the valve diameter."

Assuming that the combustion chamber has been modified to unshroud the valves so they have some breathing room all 'round, and with (say) a

33mm valve, the lift would only need to be 8.25mm (ignoring the valve stem). With a 1.1:1 rocker, this comes to lift of 7.5 at the cam, or .295 inches -- just about exactly the lift of the stock cam.

Has anyone (besides performance cam manufacturers) measured the torque of the 1600 DP engine with stock vs higher lift cams?

You don't need a counterweighed crank unless you rev the engine past

5000 rpms a lot. Sounds like you aren't planning to. Balancing however is a must. They aren't mutually exclusive. The Counterweigh operation would bring you a slower revving engine, but one that will be well balanced and wouldn't flex at high revs. Normal balancing of std crank is all *you* need, in your application.

I've got a few :-D

1) if the cam, or lifters were "broken in" with a different counterpart, the wear patterns in them would not match. This would result in rapid wear. Until the softer of the two has conformed to the shapes of the harder one, or gotten totally wiped out. :) Same *could* happen if you got the original lifters mixed up... ideally they should go back in the very same lifter bores they came out of when you tear an engine apart. However this is not a big risk, IMHO, with used, stock parts. 2) aftermarket lifters, new or used, doesn't matter: Material hardness is likely to be different that that of the original lifters. (Those would match with an original stock cam). The softer surface again is at high risk of getting wiped out. I've seen both lifter heads get trashed, and cams wear dramatically. So... whatever cam you choose, you need to choose a matching set of lifters. Aftermarket cam and lifters are made of softer alloy than original VW parts. There you have it. Don't mix and match. Thr break in period is critical for new parts, as they will "self harden" during the first 20 minutes of engine operation. If th eprocedures for this aren't followed precisely, this self hardening phase may fail and one or both surfaces will remain soft, and get damaged almost immediately. They need pressure, heat, and lubrication in a suitable mix.

Jan

You'd get the vehicle moving, and accelerated to desired cruising speed faster. And because the engine makes more power/torque while doing so.. you don't need to push the pedal through the floor as far as you used to, to keep up with traffic. The engine will work less, wear less, and consume less gasoline. In theory at least. In practise, people just enjoy the new power and utilize it.

Then why do people use cams with 10mm, 11mm and a lot more lift? Granted, at this end of the spectrum they are probably using larger valves too.

I don't fully buy that. A stock VW cam has around 7mm lift at the cam. That's not a whole lot, and a "measly" 2mm increase in lift already does a lot. Go to

and search their many forums for discussion on "ratio rockers", to find out more about this. Real life experience wipes it's ass with theory sometimes ;)

I have no knowledge of this.

Maybe we should ask the dyno-happy Jake Raby about it :)

Jan

I dunno. 'Cause everyone says that they are better? This market seems to be full of stuff that no one really needs, that does not confer anything of real value (near as I can tell) but sells because it looks neat-o or because the racing guys use it. If many of the fellows who modify their VW's are like my 18 year-old stepson, they'll buy anything that someone tells them they need.

I'm just trying to separate the reliable stuff that is truly of use in the Wonderbus from the stuff that everyone says is good because that's what they heard.

Show me the tests. SHOW ME THE TESTS!!!!

Yes, let's! Doesn't he post to type2.com's mailing list?