Does a fellow need a substantial piece of equipment to remove valves? Bentleys shows a rather formidable-appearing "Valve Spring Compression Tool being used to push spring retainer down valve stem against spring tension (single carburetor engine)."
They show a smaller, though odd, device for doing dual-carburetor engines. I have the single carb style engine.
(Bentley's green bus/van service manual)
It's just a long arm with a handle grip that pivots on the rocker arms. There are screw types that look similar to a C-clamp, too.
The tool does make life a lot easier, but I did valve springs using a properly cut little piece of wood to protect the combustion chamber on one side of a C clamp with a socket (from a socket wrench) pushing down on the reatainer, spanning the valve. If ya screw up and a spring goes ballistic, you can get really hurt. Be carefull.
On Mon, 24 May 2004 18:48:38 -0700, "Mike Rocket J. Squirrel Elliott" ran around screaming and yelling:
i have one of these style compressors as well as a "universal" valve spring compressor...this will work great with the head removed from the engine(*would need to be to replace a valve obviously)
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No.
The standard VW bench-top cylinder head tool is about $30. cip1.com carries them. p/n C26-000-129.
Or you can make one; it's just a simple lever with shoe that matches the diameter of the valve spring retainer. There's a couple of PVC pipe fittings that will work. Lever is just... a lever. Base and the standards supporting the fulcrum bar can be wood. Fulcrum bar can be anything suitable: Piece of plastic pipe, chunka electrical conduit, water pipe, tire iron...
Or you can pick up the standard C-frame OHV compressor from your FLAPS.
Worse-case you drill big enough to pass the keepers, through the middle of a board. One of your buds pushes down on the board while you pop the keepers free when they poke through.
Now you need a whetstone. Little one, like for your pocket knife. Put the CORNER of the whetstone into EACH of the three grooves, one at a time, and rub it around the circumference of the valve stem.
or use a bit of #600 wet & dry carbide paper.
(Because the keeper raises a feather of metal on the edge of the groove that is LARGER in diameter than the valve GUIDE. If you just shove the valve down through the guide that feather of metal plows a nice groove down the wall of the guide and ruins it.)
Valves are easy. Valve guides are not. Stoning a seat is easy but you need not only the stones but the driver and the diamond facing tool to re-face the stone.
Valve seats are difficult, not because they are hard to remove (run a bead of weld around two opposite sections of the inner wall of the seat. Then pour a cup of COLD water on the thing. Differential cooling of the weldment turns the circular seat into an oval that pops itself loose from the head). Then you have to re-machine the recess to accept your new, over-size seats, which must be shrunk into place with a differential of at least 500 degrees F... which is kinda hard to get because the upper limit for the head is only 350 [go higher, you run the risk of cracks] which means you want the seats chilled down to about -150 degrees... and dry ice is only -121. But there it is.
Once the new seats are pressed into their perfectly concentric recesses, as determined relative to the perfectly new guide you've just installed, you use a set of stones having angles of 30, 45 and 70 degrees to establish the sealing surface, the width of which is a function of the size of the valve and its purpose. For a car engine, stock intakes, you can have up to 3.5mm of sealing surface; exhausts about 2.5mm.
Then you lap the valves to marry them to the seats with a gas-tight seal.
Easy. Once you know how. And acquire the tools.
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(Bentley's green bus/van service manual)
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...is an ABRIDGED version of the real thing. Read the fine print.
The missing bits are where they say "Return the part to the dealer for service," [or words to that effect]. Yeah, that sounds like a good idea. I'll just run it down to the Buick-Oldsmobile-Honda-Humvee-Volkswagen dealer and let them take care of it.
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If the heads need new seats or guides, buy a new factory-built head (presently about $125).
Otherwise, replace the exhaust valves (about $7 each) and lap them in. The intakes are probably okay and may be reused, although they should be re-ground. But the odds are, new valves will cost less than the machine shop will charge to regrind them.
-R.S.Hoover
Thanks for the pointer.
[excellent information on how they work and how to build one regretfully snipped, along with techniques for installing valves -- print out Bob's post and read it] [then description of how one goes about replacing valve seats follows and snipped. Suffice it to say that Bob has it sorted out and let it double-suffice to say that it is not beginner-level machinery work, but is is, as Bob says, "Easy. Once you know how. And acquire the tools."]
Along with a bounty on a 71 bus Owner's Manual, I'm posting one for a service manual.
Yeah, I saw that and my eye felt just as jaundiced.
Rookie question (that's something new for me! NOT!): this engine is purported to be a 1776. Will ye vanilla-flavored DP 1600 engine head work?
The grinding compound / Prussian Blue technique.
Speedy Jim
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No.
The spigot bore -- the recess in the head where the cylinder goes -- has to match the diameter of the jugs. If you're using bigger jugs then the spigot bore has to be opened up to match.
The tricky bit there is that doing so also DEEPENS the chamber by some amount... not a bunch, if the work is properly done, but it alters the engine's geometry -- the rocker arm is now closer to the center-line of the crankshaft
-- AND it raises the compression ratio.
Bottom line: Any time you depart from stock dimensions you have become the DESIGNER of an entirely new engine. The responsibility for adjusting the compression ratio, volumetric balance and valve train geometry is now YOURS, not Volkswagens.
In order to promote sales the magazines and the 'experts' brush aside such details as 'unimportant' -- no thinking required. That attitude guarantees a lot of improperly assembled engine that never last very long, a point that should have a familiar ring by now :-)
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When adjusting your CR one of the most critical dimensions is the 'squish' area, that narrow gap between the top of the piston at TDC and the flat perimeter of the combustion chamber. This area exists largely to promote turbulence within the chamber at the time of ignition, thereby ensuring more complete combustion. But as combustion occurs the flame-front serves to COMPRESS the as-yet-unburned fuel/air mixture INTO that squish area, resulting in a dramatic increase in both pressure and temperature.
Make the squish area too small and you will precipitate detonation... even through the effective compression ratio, octane rating and ambient air temp say it can't happen.
So what's the proper size of the squish area? That's the tricky bit, because determination of the idea size depends on the diameter of the piston as one of the factors. Volkswagen used pistons as small as 75mm and as large as 85.5, setting the squish-height slightly wider as the diameter of the piston increased. The PERFECT squish height becomes the result of an equation having half a dozen variables and the correct answer defines a range of squish height in which detonation will NOT occur.
Bottom line #2: For a daily driver when running jugs that are bigger than stock you have to accept a compromise solution, typically a compression ratio of no more than 7.3:1 and a squish-height of about sixty thou for 90.5's and up to 80 thou for 94's. Anything less narrows the acceptable solutions to the equation to the the point where detonation MAY occur under worse-case condtions (and usually will).
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I know how happy you'll be to read all this but please keep in mind I'm just the messenger. Your engine is governed by rules of physics and engineering; after-market retailers and VW-specific magazines are not :-)
-Bob Hoover
LOL! This is why I asked the question! The challenges that this bus presents continue to amuse me. This bus was planted into my life to teach me patience. One good thing is that it forces me to run errands on my bicycle, which is never bad for my health.
I'll cross fingers that the head is not so messed up that replacement or expensive re-machining are required.
But I won't count on it!
Oh ho! The secret Ebay source of all items material in the world!
this is the one i have...
Sears has everything.
Yes, they do! I love craftsman tools. Too bad my local Sears doesn't have completely stocked shelves. I have to drive an extra 10 miles to the big store when I need the odd-ball stuff.
Mike: please continue trying to fix the bus.... It has made this group a very good tech resource once again....
Have no fear, Eduardo. I've got my teeth in it now and ain't letting go.
The nice thing about being the Designated Beginner is that I get to ask the rookie questions that I bet others would like to ask but are too shy to.
"Eduardo Kaftanski"
Agreed.
-- Scott
"Mike Rocket J. Squirrel Elliott" wrote in news: snipped-for-privacy@adelphia.com:
There comes a time with an old car when you have to say, I've had enough. Sometimes it's because the repair is far beyond your expertise, or because you've been pouring a coupla hundred bucks a month into it for the last year, or because rust has finally won the battle. Such was the case with my learner, a 66 POS Bus. I did strip off what I could for people...
And yet--the perversity of inanimate objects!--sometimes we find we've put so much into the relationship that letting go is out of the question. My convertible is My Car, period. Whatever it takes.
I'm glad you're pressing on, Mike. I don't know if the Wonderbus is a keeper, but I sure don't think it's time to say adios.
I let got Walter (1961 bug) for US$500 today to finance house improvements, and to clear the driveway for a 1992 Peugeot I intend to repair...
This time the deciding factor to sell was Sonia telling me 'one non running car at a time' :)
Eduardo Kaftanski wrote in news:c9b92n$lcm$ snipped-for-privacy@enriqueto.nn.cl:
There is an alt.autos.peugeot.* group, but most of the posts there were OT.
At one point we had 66 Bus POS 70 Beetle convertible 72 Dodge Dart 74 Mustang and it was more like 'one running car at a time.'
There is a picture somewhere of them all parked on the front lawn.
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