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viiking
Samba Member
Joined: May 10, 2013
Posts: 3217
Location: Sydney Australia
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 Posted: Sun May 11, 2025 4:34 pm Post subject: Re: 1600 dp valve guide specs |
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| modok wrote: |
The clearance is what matters.
You haven't said if the valve stems are worn or just made small to start with.
If the stems are chromed then you have to keep in mind that the chrome is only so thick.
New valves being more like .312" is fairly common, and that's workable but frustrating, as the cost of smaller pilots and carbide or diamond reamers to do a good job...... the bastards just cost you 600$ to re-tool if you weren't ready for it. or you just let it be loose and it will work but not as well. |
I don't know the history of the engine. I have measured the valves and they all seem to be on the small side. Measured each valve top, middle and bottom and the guides with a split ball gauge and micrometer.
I'm guessing that the valves were made on the smaller end of the spec.
My gut feel was that it was the clearance that was the most important but just wanted some other opinion.
The oft quoted internet generic valve guide clearance is 1 to 3 thou (.025-.076mm) for inlets and 2 to 4 (.05-0.10mm) shows that all my clearances are well within these. Bentley however only provides a "rock" limit of 0.8mm but does not show a procedure for this e.g. how far the valve protrudes from the head when measuring so I have not checked this.
_________________
1968 1500 RHD Lotus White Beetle since birth. In the hospital for major surgery
1966 Lancia Flavia Pininfarina Coupe - in the waiting room
Discharged: 1983 Vanagon, 1974 1800 Microbus,1968 Low Light,1968 Type 3 |
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modok
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Joined: October 30, 2009
Posts: 27687
Location: Colorado Springs
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| Posted: Sat May 10, 2025 4:39 pm Post subject: Re: 1600 dp valve guide specs |
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The clearance is what matters.
You haven't said if the valve stems are worn or just made small to start with.
If the stems are chromed then you have to keep in mind that the chrome is only so thick.
New valves being more like .312" is fairly common, and that's workable but frustrating, as the cost of smaller pilots and carbide or diamond reamers to do a good job...... the bastards just cost you 600$ to re-tool if you weren't ready for it. or you just let it be loose and it will work but not as well. |
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viiking
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Joined: May 10, 2013
Posts: 3217
Location: Sydney Australia
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| Posted: Sat May 10, 2025 4:05 pm Post subject: Re: 1600 dp valve guide specs |
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Anyone?
_________________
1968 1500 RHD Lotus White Beetle since birth. In the hospital for major surgery
1966 Lancia Flavia Pininfarina Coupe - in the waiting room
Discharged: 1983 Vanagon, 1974 1800 Microbus,1968 Low Light,1968 Type 3 |
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viiking
Samba Member
Joined: May 10, 2013
Posts: 3217
Location: Sydney Australia
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| Posted: Thu May 08, 2025 3:52 am Post subject: Re: 1600 dp valve guide specs |
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I know this is an old thread but I thought it better to continue this than start a new one.
General question about valve to guide clearance.
I have a spare engine that has valve stems that are close to the minimum but the valve guide clearance is well within the tolerance. It appears that generic guides were machined/honed to maintain the correct clearance.
So, what is the most critical dimension with the valve guide clearance? Is the absolute diameter of the valve stem important as long as the guide clearance is in spec?
The engine ran well before being pulled so I don't necessarily want to replace the valves and guides if I don't have to.
_________________
1968 1500 RHD Lotus White Beetle since birth. In the hospital for major surgery
1966 Lancia Flavia Pininfarina Coupe - in the waiting room
Discharged: 1983 Vanagon, 1974 1800 Microbus,1968 Low Light,1968 Type 3 |
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Adriel Rowley
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Joined: October 12, 2006
Posts: 4823
Location: Mesa, Arizona
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| Posted: Wed Mar 30, 2011 6:42 pm Post subject: |
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| modok wrote: |
3000 miles is nothin, they are probably like new or at worst they might need refaced.
The area where the valve contacts the seat is called the face.
Valves can be refaced with a.........valve grinding machine
I believe that if there is no signs the valves are worn out or have been running in bad conditions, they can be refaced and reused as many times as you want.
By inspecting the keeper grooves, and the stem ends, and using a mic to measure the diameter of the stem, and looking at the face and margin and looking at the coloration and observing how much metal is removed on the grinder to reface the valve..............you can make an educated guess that it is ok to use again.
in short, you bet. If there is nothing wrong with em' then they are OK
When in doubt, replace |
That was exactly what I was thinking. I can use the machine shops tools, as I volunteered there for an engine build, which I ended up having to pay for. So, I just walk in and ask if anyone is using what I like to use, and if not, I use it. Bet if I brought beer make things go even better.   Way too bitter and too much of a light weight, so not for me.
Just like a lot of things: all a bet, and if you do not want to, have to replace. Russ never replaced the intakes as he said they never got hot, so take as willed.
_________________
Please consider I am Autistic, so I process information differently and still working on social skills. Thanks.
Dad's 1964 Beetle purchased September 1968.
https://www.thesamba.com/vw/forum/viewtopic.php?p=9252810#9252810
1971 Sunroof Squareback with Fuel Injection
http://www.thesamba.com/vw/forum/viewtopic.php?t=219811&highlight=squareback+rejuvenation |
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modok
Samba Member
Joined: October 30, 2009
Posts: 27687
Location: Colorado Springs
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| Posted: Wed Mar 30, 2011 6:35 pm Post subject: |
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3000 miles is nothin, they are probably like new or at worst they might need refaced.
The area where the valve contacts the seat is called the face.
Valves can be refaced with a.........valve grinding machine
I believe that if there is no signs the valves are worn out or have been running in bad conditions, they can be refaced and reused as many times as you want.
By inspecting the keeper grooves, and the stem ends, and using a mic to measure the diameter of the stem, and looking at the face and margin and looking at the coloration and observing how much metal is removed on the grinder to reface the valve..............you can make an educated guess that it is ok to use again.
in short, you bet. If there is nothing wrong with em' then they are OK
When in doubt, replace |
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Adriel Rowley
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Joined: October 12, 2006
Posts: 4823
Location: Mesa, Arizona
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| Posted: Wed Mar 30, 2011 6:22 pm Post subject: |
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| modok wrote: |
In theory it should be possible to replace the guide and still have it lined up with the seat.
Henry Ford believed this too. Many engines built before 1950 were designed in such a way that the guide could be replaced in the field.
It didn't work out so well so they quit doing it.
In modern times it is almost an issue of probablilty, maybe 20% of the time it would work, but the other 80% of the time it doesen't.
here are the reasons:
The seat wears too, if the guide is worn out why would the seat be ok?
Seats wear too; they get wide and groovy and lopsided.
Sometimes the guide can wear out but the seat is ok, but not often.
The head warps. Seats sink into the head some. The guide bore becomes bananna shaped and so on. Even if the guides and seats were made from supermetal that never wears you'd still need a valve job someday.
That is unless your heads are made of unwarpable super metal too instead of aluminum.
Industry standard for valve seat runout is, and has been, .002" or less, that is less than one hair. It is not likely to replace a guide and ream it and have it line up the same as it was before. Even .001" off center at one end of the guide would become over .002" at the seat due to the distance.
The reason aircooled have a reputation for eating exhaust valves is because the seat and guide wear out, or go off center due to warp, and this fatigues and overheats the valve causing it to break.
If the valve is a good fit in the guide and the seat is fresh a valve runs cool and happy. If the guide is worn out and the seat is wonky the valve gets hot and bent around and breaks.
The bently manual has specs for the guides, stems, and seats. |
So then I should just replace the guides, and have the machine shop grind the seats. Then I install the valves. Thank you for the advice. 
Oh and the seats might be fine as the head(s) over heated and the guides went out of tolerance. But, that is might.
I do not have it handy: back in San Diego and I am currently taking classes in Tempe.
Thank you again for all the help. Now I can get the grunt and dirty work done and save money and know good chance things are done right.
If the valves have 3,000 miles on them, do they need to be replaced? If not, what has to be done?
_________________
Please consider I am Autistic, so I process information differently and still working on social skills. Thanks.
Dad's 1964 Beetle purchased September 1968.
https://www.thesamba.com/vw/forum/viewtopic.php?p=9252810#9252810
1971 Sunroof Squareback with Fuel Injection
http://www.thesamba.com/vw/forum/viewtopic.php?t=219811&highlight=squareback+rejuvenation |
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modok
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Joined: October 30, 2009
Posts: 27687
Location: Colorado Springs
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| Posted: Wed Mar 30, 2011 6:12 pm Post subject: |
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In theory it should be possible to replace the guide and still have it lined up with the seat.
Henry Ford believed this too. Many engines built before 1950 were designed in such a way that the guide could be replaced in the field.
It didn't work out so well so they quit doing it.
In modern times it is almost an issue of probablilty, maybe 20% of the time it would work, but the other 80% of the time it doesen't.
here are the reasons:
The seat wears too, if the guide is worn out why would the seat be ok?
Seats wear too; they get wide and groovy and lopsided.
Sometimes the guide can wear out but the seat is ok, but not often.
The head warps. Seats sink into the head some. The guide bore becomes bananna shaped and so on. Even if the guides and seats were made from supermetal that never wears you'd still need a valve job someday.
That is unless your heads are made of unwarpable super metal too instead of aluminum.
Industry standard for valve seat runout is, and has been, .002" or less, that is less than one hair. It is not likely to replace a guide and ream it and have it line up the same as it was before. Even .001" off center at one end of the guide would become over .002" at the seat due to the distance.
The reason aircooled have a reputation for eating exhaust valves is because the seat and guide wear out, or go off center due to warp, and this fatigues and overheats the valve causing it to break.
If the valve is a good fit in the guide and the seat is fresh a valve runs cool and happy. If the guide is worn out and the seat is wonky the valve gets hot and bent around and breaks.
The bently manual has specs for the guides, stems, and seats. |
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Adriel Rowley
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Joined: October 12, 2006
Posts: 4823
Location: Mesa, Arizona
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| Posted: Wed Mar 30, 2011 5:37 pm Post subject: |
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| modok wrote: |
dude, you all mixed up
You linked video of a guy using a sunnen VGS machine.
That is a kind of machine that cuts valve seats, not simply a drill press
see if there is a video of this guy cutting the seats too!
The three best ways to cut a valve seat is to grind it with Sioux equiptment.
OR cut it with a serti or sunnen VGS machine (stands for Valve Seat and Guide)
Using grinding compund on the valve and seat, and LAPPING is something else. It can smooth the surface but cannot correct the shape, angles, or width of the valve seat, so it doesen't do a whole lot. |
Well then I know the two other places did not have anything like that. Trust me, I know what a drill press looks like and that is all Russ had. I did not dig, so might have been hand grinding tools, but from what you are saying it is very doubtful. In short, he replaced valve guides, and seems did not grind the seats.
Ah got what you are saying. So why when replacing valve guides do you need to grind the seats? The guides should be in the same plane(s) as before, right?
I was saying to "lap" only as an indication of whether all was aligned correctly. Just a thought.
And to be clear, I really have no space to put anything, as semi-transient. About 80 percent of all auto tools and parts are in the Squareback, which is at a very good friends house.
_________________
Please consider I am Autistic, so I process information differently and still working on social skills. Thanks.
Dad's 1964 Beetle purchased September 1968.
https://www.thesamba.com/vw/forum/viewtopic.php?p=9252810#9252810
1971 Sunroof Squareback with Fuel Injection
http://www.thesamba.com/vw/forum/viewtopic.php?t=219811&highlight=squareback+rejuvenation |
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modok
Samba Member
Joined: October 30, 2009
Posts: 27687
Location: Colorado Springs
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| Posted: Wed Mar 30, 2011 5:23 pm Post subject: |
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dude, you all mixed up
You linked video of a guy using a sunnen VGS machine.
That is a kind of machine that cuts valve seats, not simply a drill press
see if there is a video of this guy cutting the seats too!
The three best ways to cut a valve seat is to grind it with Sioux equiptment.
OR cut it with a serti or sunnen VGS machine (stands for Valve Seat and Guide)
Using grinding compund on the valve and seat, and LAPPING is something else. It can smooth the surface but cannot correct the shape, angles, or width of the valve seat, so it doesen't do a whole lot. |
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Adriel Rowley
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Joined: October 12, 2006
Posts: 4823
Location: Mesa, Arizona
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| Posted: Wed Mar 30, 2011 5:07 pm Post subject: |
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| RockCrusher wrote: |
I see......only used the Neway (correct) cutters one time at another guys shop for a set of heads away from home base. Seemed to work ok. The shop was Jr. Dragster place.
We still grind seats here as a Serti is out of our reach right now. Rebuilt, trued and calibrated B&D valve grinder and Sioux seat grinder/driver. Those who are proponents of the Serti and like machines will tell you that you can't get a great or even good job by grinding and maybe on a $60K-100K hi-tech super duper double trick extra special engine the difference can be checked but I would argue that until those machines came out grinding was IT and gazillians of fabulous engines had exactly that method used. It is more about equipment condition and operator knowledge/technique that makes most of the difference.
RC |
So grinding does work? Then why did modok say the fancy maching was the only way?  Or is there a differance between the Neway and Sioux? Sorry I am not getting it... 
_________________
Please consider I am Autistic, so I process information differently and still working on social skills. Thanks.
Dad's 1964 Beetle purchased September 1968.
https://www.thesamba.com/vw/forum/viewtopic.php?p=9252810#9252810
1971 Sunroof Squareback with Fuel Injection
http://www.thesamba.com/vw/forum/viewtopic.php?t=219811&highlight=squareback+rejuvenation |
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Adriel Rowley
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Joined: October 12, 2006
Posts: 4823
Location: Mesa, Arizona
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| Posted: Wed Mar 30, 2011 5:02 pm Post subject: |
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| modok wrote: |
Sorry about the Amish joke, poor taste on my part.
I was trying to convey that running a reamer through bronze takes a lot of force, you will see.
The guide ID needs to be adjusted based on the size of the stem.
See the clearance specs above.
The last three sets I did I diamond reamed the guides to .3145", as the stems of my PEP valves were all right around .3120".
We have a .3142 pilot for the serti so it all worked perfect.
The guide ID can be checked by:
-expandable ball gauge
-mini snap gauge
-special valve guide bore gauge
-using a pilot as a go/no go gauge
The guide bore size in the head can also be checked with a ball or snap gauge OR by using other guides as go/no go gauges
as for the guides; a .002 oversize brand X guide is .002 thou bigger than a brand X STD size guide.
After installing new guides the seats need to be recut or reground so the seat is concentric with the new guide and the proper width and location on the valve. I believe in Sioux grinding equiptment, VGS-20, or Serti.
Those stupid DIY file cutters are kids stuff, I would not use them on my lawn mower. (ok, actually I did once but now I know better)
I would be happy to list what tools will be needed to do an industry standard valve job, and give general advice on how to use them and check your work.
Unfortunately, if you do not currently have ANY of these tools it will take quite a while and quite a lot of money to collect them all. |
The head rebuilding shops I have seen have very minimal tools. About the only power tool is a drill press and no seat grinder, even if replacing the valve guides. So why is not possible to do the same?
What if the valves are stock 8mm stems? Why not ream to one specification, or are they all different? Here is how I have seen it done.
Link
So no standard to outer diameter on oversize valve guides?
Why can I not just lap the valves to be sure all is good, by checking where it ground?
Well if I know what I am looking for, I will keep my eyes open if I do go to a sale this summer.
Love to have your critique of my work. When I do get started, will be sure to update and document.
| modok wrote: |
I just looked at Neway's web page, it says:
"no need to lap like old fashoned grinding equiptment"
hahahaha THE IRONY
You can grind any seat from iron to stellite to stainless to high nickel, no lapping needed if done right. WIth a full set of sioux pilots and stones I can grind any seat perfect.
There are alot of jobs the neway cutters are not able to handle, and on used vw heads those exhaust seats can get REALLY HARD and crispy, the files don't like chewin on that |
Good to know. As far as I know, Russ never touched the seats. He was Volkswagen trained, and had rebuild many heads and even have a set myself and they work fine. I may be wrong, but as said prior, there was not machine for this task.
_________________
Please consider I am Autistic, so I process information differently and still working on social skills. Thanks.
Dad's 1964 Beetle purchased September 1968.
https://www.thesamba.com/vw/forum/viewtopic.php?p=9252810#9252810
1971 Sunroof Squareback with Fuel Injection
http://www.thesamba.com/vw/forum/viewtopic.php?t=219811&highlight=squareback+rejuvenation |
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RockCrusher
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Joined: August 03, 2010
Posts: 4596
Location: Parkesburg, PA
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| Posted: Wed Mar 30, 2011 12:22 am Post subject: |
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Their shop is 99% performance and resto engines. They were showing me (years ago) where they were making new valves for a 1922 REO straight six that had mortises thru the tops of the valves with rectangular pins that held the valves like a tenon joint. I didn't know it at the time but I later worked with the owner of the car and got a ride in the completed project. Small world huh? Always some crazy stuff in there when I stop in. Makes our humble little VW shop seem like the bleeding edge of nuttin........
It's always good to know that anything I need beyond our capabilities is only a short drive away.
_________________
[email protected] Please use email for all general inquiries.
I will be happy to speak to anyone who has a serious inquiry (meaning real potential business for RC enterprises) or a parts order. Due to machining noise causing missed calls all calls will be returned promptly. |
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modok
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Posts: 27687
Location: Colorado Springs
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| Posted: Wed Mar 30, 2011 12:11 am Post subject: |
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hell yeah. shops that work on anything are the most fun
today I bored a john deere D out to 7 inch bore, honed a buick v-6, sleeved two bores of a cummins B block, and line honed a mitubishi/chrysler.
Never done a lotus, but who knows what will come in next week, maybe I get lucky! |
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RockCrusher
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Location: Parkesburg, PA
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| Posted: Tue Mar 29, 2011 11:57 pm Post subject: |
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The guys I use as my backup who do our rotational balancing and whose dyno we use have a terrific father son shop and I mean they do all kinds of cool crap....cup engine contracts, huge into BMW road race right now, antique engine resto's, blown Lotus slant 4 engines and big into vintage Porsche racing engines right now also, and the traditional stuff....you get the idea. They have not just the full engine machine shop equipment but full machine shop as well for custom fab work like full bottom end girdle/main cap setups for the fragile Lotus bottoms, etc. That was just to say that these guys are no rinky tink BS shop.
Soooooooo....they have the Serti but maintain all the old equipment as well for exactly the reasons you stated.
That was a lot for a little........
_________________
[email protected] Please use email for all general inquiries.
I will be happy to speak to anyone who has a serious inquiry (meaning real potential business for RC enterprises) or a parts order. Due to machining noise causing missed calls all calls will be returned promptly. |
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modok
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Posts: 27687
Location: Colorado Springs
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| Posted: Tue Mar 29, 2011 11:44 pm Post subject: |
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i agree 100%
the Serti is good for production type work, but even it is not without limitations.
i have had the serti fail on honda, detroit, cat 3406, 1.8 20 valve audi, cummins C and more. Either it is not strong enough to cut the hard seat is some HD engines, or does not center well enough if the guide diameter is small and deep in the port.
grinding can work good 100% of the time, even on fancy new engines |
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RockCrusher
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| Posted: Tue Mar 29, 2011 11:27 pm Post subject: |
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I see......only used the Neway (correct) cutters one time at another guys shop for a set of heads away from home base. Seemed to work ok. The shop was Jr. Dragster place.
We still grind seats here as a Serti is out of our reach right now. Rebuilt, trued and calibrated B&D valve grinder and Sioux seat grinder/driver. Those who are proponents of the Serti and like machines will tell you that you can't get a great or even good job by grinding and maybe on a $60K-100K hi-tech super duper double trick extra special engine the difference can be checked but I would argue that until those machines came out grinding was IT and gazillians of fabulous engines had exactly that method used. It is more about equipment condition and operator knowledge/technique that makes most of the difference.
RC
_________________
[email protected] Please use email for all general inquiries.
I will be happy to speak to anyone who has a serious inquiry (meaning real potential business for RC enterprises) or a parts order. Due to machining noise causing missed calls all calls will be returned promptly.
Last edited by RockCrusher on Tue Mar 29, 2011 11:58 pm; edited 1 time in total |
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modok
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Posts: 27687
Location: Colorado Springs
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| Posted: Tue Mar 29, 2011 11:22 pm Post subject: |
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I just looked at Neway's web page, it says:
"no need to lap like old fashoned grinding equiptment"
hahahaha THE IRONY
You can grind any seat from iron to stellite to stainless to high nickel, no lapping needed if done right. WIth a full set of sioux pilots and stones I can grind any seat perfect.
There are alot of jobs the neway cutters are not able to handle, and on used vw heads those exhaust seats can get REALLY HARD and crispy, the files don't like chewin on that
Last edited by modok on Tue Mar 29, 2011 11:31 pm; edited 1 time in total |
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modok
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Location: Colorado Springs
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| Posted: Tue Mar 29, 2011 11:10 pm Post subject: |
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There have been many brands of them, some are better than others I'm sure. I'm thinking they were made by neway? i forget
The advantage of grinding the seats, is it takes very little force on the pilot, and naturally cuts round and on center with no other support.
Cutting valve seats often results in wavy or ovaly seats or seats with a lot of runout, the solution for that has been very stout machines like the VGS-20 or Serti. The machine FORCES the cutter to track round. |
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RockCrusher
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| Posted: Tue Mar 29, 2011 10:59 pm Post subject: |
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By "file type" are you referring to the hand driven carbide cutters Goodson is selling?
_________________
[email protected] Please use email for all general inquiries.
I will be happy to speak to anyone who has a serious inquiry (meaning real potential business for RC enterprises) or a parts order. Due to machining noise causing missed calls all calls will be returned promptly. |
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