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Thu Jan 01, 2015 12:53 am

Whats the diameter of a valve stem 1600 dual port.
Whats the ID of valve guide supposed to be.
Another words what the difference spec.

Also want to know if reaming is required in new guides.
Did anyone here buy a reamer, if so from who.

Thu Jan 01, 2015 1:29 am

Alas, no longer a simple answer. Valves come in 8 or 9 mm varieties and I've seen heads with both. I have also come across valve guides of different diameters for repairing loose ones (although I forget the precise dims)

Why do you need to know?

It's fairly simple to check with the heads on involving stiff card and a slot 8mm wide. Make sure the card will fit inside the valve spring. If the 8mm slot is too small, it should be a 9mm valve

Check out this page for an idea of the kind of valve guides available

http://vwparts.aircooled.net/SearchResults.asp?Search=valve+guide

In short, dont buy anything until you know what you have got!

Thu Jan 01, 2015 4:11 am

Most VW valves are 8mm. As for clearance between stem and guide, the guide is reamed with an 8mm reamer and the valve must slide back and fourth freely.
With the springs removed, you can check used heads by rocking the valve in the guide while it is open. A little is movement is OK and you will find a bad guide quickly.

Thu Jan 01, 2015 8:22 am

So from the question it sounds like you are replacing valves and guides.....not just checking an engine you are going to buy for worn guides....right?

If so....there are much, more precise specs necessary than just checking that there is smooth movement.
The most common method VW used....which is kind of a "you can do it in the field with readily available tools".....method....is to remove the spring and retainers. Push the valve stem down so the valve is essentially at full lift....and place a dial indicator perpendicular to the tip of the stem. Rock the valve back and forth and read the play.

Now.....excellent machines shops, racing machine shops and most watercooled engines shops will scream blasphemy and burn you in the parking lot as a heretic.....and rightfully so! :wink: .....for using this method. This is because they do not know the history behind the engine and the car.
This method was devised to allow a functional rebuild or service...literally in the field. It assumes that you probably won't have the tools to actually get picky and adjust valves geometry by shimming or adjusting pushrod lengths.....so it give you a method for refurbishing valves guides with a range of tolerance good enough to keep from getting them greatly too tight or too loose. It will run exellently or just average....may burn a little oil or not....may have a little shorter life or not.....but will not be too tight using this method. It can also be done with care and patience with a good vernier or dial caliper in lieu of a dial indicator.

But....any decent head shop that does valve guides should have small bore gauges to allow them to ream to an exact tolerance instead of doing a rock test. They should also be able to pull up the tolerances....but if not. ....it will pay to provide the tolerances to them.

Bear in mind....as mentioned...some engines had 9mm exhaust valve stems....like most type 4 engines. Many type 1s have been rebuilt with 9mm stems on exhaust or even on intakes in some cases. Unless the valve material is special, the tolerances I list should still stand. Any particular 8mm valve from a different mfg...may start out new smaller or larger than the min/max sizes I list....but the stem to guide tolerance and wear limits shoul still be fine.

The factory specifications for valves and guides for types 1,2,3 1600:

Intake:

Stem OD: 0.3126"-0.3129" wear limit: 0.3110"
Guide ID: 0.3150"-0.3157" wear limit: 0.3173"
Stem to guide gap: .0024"-.0028"
Rock test: .009"-.010" wear limit: 0.031"

Exhaust:

Stem OD: 0.3114"- 0.3118" wear limit: 0.3102"
Guide ID: 0.3150"- 0.3157" wear limit: 0.3173"
Stem to guide gap: .0036"- .0039"
Rock test: .009-.010" wear limit: 0.031"

You will notice that the exhaust valve has a larger tolerance. This is because it runs hotter.

These specs came from the 1971 to 1974 without guesswork book. Ray

Thu Jan 01, 2015 10:13 am

Yes I am going to put new guides in my self. I have a press. It will be a beater stock engine that gets little use. I know the rock them test. Jus wondering if new guides come with an ID that always needs to be reamed.

Have you herd of the trick:

Turning the top of the guide OD down to except vw rabbit seals.

Swapping the rocker shafts around because the are often worn.

Thu Jan 01, 2015 10:46 am

Make sure you core drill the old guide before removal. I use 5/16" bit with the end turned down to fit the guide i.d. Spot face the top of the guide flush with the guide boss and drive guide out toward the combustion chamber to remove. I use an adjustable reamer for the guide ID. Do not order guides before removing the old guides to verify correct o.d. needed. Many heads now have oversize guides from previous rebuilds. Guides after being installed will need to be reamed to size. If the guides are not to far out of size you can knurl the i.d. of the guides to bring it back into spec without removal! Knurling requires special tools though that not everyone has! Good luck!

Thu Jan 01, 2015 11:20 am

stevehenderson wrote: Yes I am going to put new guides in my self. I have a press. It will be a beater stock engine that gets little use. I know the rock them test. Jus wondering if new guides come with an ID that always needs to be reamed.

Have you herd of the trick:

Turning the top of the guide OD down to except vw rabbit seals.

Swapping the rocker shafts around because the are often worn.

ACVW Heads require no stem seals whatsoever. In some cases this may, actually, interferee with, lubrication. They almost always crack apart due to heat and end up in thd crankcase.

Flipping over the rocker shafts may move the fulcrun point to a cleaner area but does not change the overall tolerance inside of the rocker arm. Worn is worn.

If they are galled badly you can replace them for cheap.....but typically just polish them and they will be fine.

Yes virtually all valve guides come undersized to be reamed to size. This is necessary as too tight or too loose....is not just a geometry and oil usage issue....it makes the guides more prone to cracking. Ray

Thu Jan 01, 2015 2:30 pm

K-line brand reamers are very good IMO, Goodson is a supplier.

As usual.........I wonder if you are asking these questions maybe you don't know the seats need to be re-cut/re-ground after changing guides.
whoever you employ to do that work probably will have a reamer or honing tool to size the guides. Putting them in yourself is probably ok way to save a few bucks.........I certainly do not enjoy it

Thu Jan 01, 2015 3:26 pm

Mofoco is in my town. and They don't even do guides only, the only individual head work they will do is valve job. Or they will exchange yours for rebuilt ones.
I trust them to at least do a stock 3 angle--$60 pair.

I was reading about adding valve seals on Bob Hovers site, but I knew he could be just and old timer doing something weird.

I just want to freshen up thees single port heads a bit. I do have a friend with a valve seat grinder and valve resurfacer, but for $60 bucks I'll just get them done professionally. Might grind the intakes my self.

Thu Jan 01, 2015 3:34 pm

Well yeah of course they don't replace guides without re-cutting seats. didn't i just explain that?

60 bucks??
I expect that is grind seats and face valves only.

a real valve job takes more than an hour to do :lol:

Thu Jan 01, 2015 4:45 pm

stevehenderson wrote: Mofoco is in my town. and They don't even do guides only, the only individual head work they will do is valve job. Or they will exchange yours for rebuilt ones.
I trust them to at least do a stock 3 angle--$60 pair.

I was reading about adding valve seals on Bob Hovers site, but I knew he could be just and old timer doing something weird.

I just want to freshen up thees single port heads a bit. I do have a friend with a valve seat grinder and valve resurfacer, but for $60 bucks I'll just get them done professionally. Might grind the intakes my self.

Don't take the lip off the back of the exhaust valve, it's there to create turbulence to reduce exhaust intake at cam overlap

Thu Jan 01, 2015 5:02 pm

What I was saying was they offer only two things.
1. Exchange your heads for rebuilt ones $160
2. Do a valve job $60
Don't know why, maybe they send them out for complete rebuilds. because they say "Rebuilt heads are currently at a four week wait time" :roll: Maybe guides and valves price would be too close to their complete rebuild exchange price.

Also I don't like taking my VW stuff to the V8 places. Mofoco is at least a VW aircooled place in Milwaukee. I don't have to pay shipping if I use them.

They will also put bigger valves in heads.

Thu Jan 01, 2015 5:13 pm

ah ok.
Rebuild means Re-surfacing and dealing with broken studs and stripped holes included.

Fri Jan 02, 2015 6:43 am

The cost of new set of valves, springs, guides and the time spent doing the work correctly makes it almost not worth rebuilding stock heads. A new set of heads is not that much more and you are starting with all new parts.
So unless these heads are something special, think about what is best in the long run.

Fri Jan 02, 2015 10:29 am

it's the vw places that skkeerr the heck out of me as far as quality of work. a vw specialty shop like cb,brothers and such are good, but bubbas vw recking&repair might not be the bets choice. removing the "lip" on the exhaust is fine and it's not ther for over lap.
you can ream a guide too big and it still be snug.guides should be reamed then honed with a stone/diamond hone, the dingle berry hones are not good for getting a straight properly sized guide. I like about .0003 on intakes and .0007 on exhaust, but that can varry with the head and app.

Tue Jul 07, 2015 4:55 pm

What is the nominal ID size of a std valve guide? I have mine pressed out and am ready to order new ones but I don't know what size to order.

Tue Jul 07, 2015 5:02 pm

Tue Jul 07, 2015 5:26 pm

The guide not the valve stem. My best estimation is 12mm. You can get .002 up to .008 oversized guides. I am going to get the .008 ones and machine them to fit

Tue Jul 07, 2015 5:39 pm

jeremyrockjock wrote: What is the nominal ID size of a std valve guide?
The outside is called the OD
I thought you might have mixed that up..... but I figured anybody who can use the word "nominal" don't make simple mistakes.

.475"-.4755" is stock
Most STD replacement guides are .476"

Shoot for .001-.002" Press fit, chamfer the edge of the bore in the head generously, and lube with anti-sieze.
The above sounds pretty simple, but it's been learned the hard way.

If you took them out.......measure them!!

Tue Jul 07, 2015 5:40 pm

LOL my bad you are right. One is .478 the other is .485 which is why i was not sure if either are std. Thanks man