TheSamba.com :: View topic

Fri Nov 28, 2014 4:08 pm

I picked up my heads from the machine shop today for a 1300. He put the valve seals on the end of the valve stem. I think they go between the keeper and the guide? Or are they not even needed? I read a few threads and some said not to use them. In my Bentley book it says to use Prussian Blue on the valve and seat and rotate to check for perfect sealing surface. Is this something that has to be done? I have none on my heads but noticed some on other heads at the shop. Or is there a way to check for no leaks with a liquid, maybe a solvent? Thanks, Casey

Fri Nov 28, 2014 7:12 pm

Wont hurt, but not necessary. As long as they do not come in contact with the top of the guide when the valve is full open.

Fri Nov 28, 2014 8:54 pm

VW did NOT use valve seals on aircooled VW engines. Unlike upright engines, the valve spring ends on the bug engine angle downwards so they don't/cant leak excess oil into the head space.

In fact, the phosphor bronze valve guides rely on the oil-splash on the spring ends and oil working up the valve stem by capillary action for their lubrication, so I would think that valve seals would be counter-productive.

The seal of the valves on the seats should have been checked by the head builder, so re-checking should not be needed.

Fri Nov 28, 2014 9:13 pm

Aussiebug wrote: VW did NOT use valve seals on aircooled VW engines. Unlike upright engines, the valve spring ends on the bug engine angle downwards so they don't/cant leak excess oil into the head space.

In fact, the phosphor bronze valve guides rely on the oil-splash on the spring ends and oil working up the valve stem by capillary action for their lubrication, so I would think that valve seals would be counter-productive.

The seal of the valves on the seats should have been checked by the head builder, so re-checking should not be needed.

Absolutely correct !
As far as the head builder goes, I check EVERYTHING that comes back from the machine shop. People today have a absence of mind these days when it comes to Math. Always check your clearances after work is done, especially...main-rod-cam journals for clearances.
What you need to check on the head when you get it back is: Valve length, valve angle, seat angle and valve /seat fit, seat and valve margins, installed valve height, closed and opening spring pressures, valve guide clearance. Check for cracks in the combustion chamber area, and cracks around the valve guide especially where it protrudes into the port area ( the guide will crack the head if it's been driven in with a hammer and drift or especially if a air hammer was used.

Sat Nov 29, 2014 7:57 am

If it is the small O ring style it will not make a difference, but I do agree with you guys that if it is a perfect seal type, toss them out of there. Is it the Oring style ?

Sat Nov 29, 2014 11:25 am

My dad rebuilds heads and he rebuilt my 40hp heads. He used Prussian blue to grind the seats and then a lapping compound to hand lap the valves to the seats. He also used the o ring type seal which is the same as the early chevy 350 seals. I don't think they'd do much as they ride on the valve itself and not onto the valve guide. It did help keeping the valves in place though. He was taught that way by a VW tech in Mexico years ago.

Sat Nov 29, 2014 2:29 pm

vdubmyk wrote: My dad rebuilds heads and he rebuilt my 40hp heads. He used Prussian blue to grind the seats and then a lapping compound to hand lap the valves to the seats. He also used the o ring type seal which is the same as the early chevy 350 seals. I don't think they'd do much as they ride on the valve itself and not onto the valve guide. It did help keeping the valves in place though. He was taught that way by a VW tech in Mexico years ago.

The seal that is used on the Pontiac V-8, Chevrolet V-8 & six, and Oldsmobile V-8 is called a umbrella seal. All three of those V-8's the valves are pointed down. The seal is used to keep oil from being sucked into the guide because oil is being rained down upon the spring& valve assy. The VW head has the Valves positioned horizontally high up so that oil is not a problem of excessively oiling the valve stem and guide so NO seal is necessary. To do a proper three angle valve job we either use angled stones, or angled cutting tools. We may lap the valves afterwards but the angles must be cut first. If all you did was lap valve you would blend the angles between the valve and the seat. The valves are cut at 45 degrees and the seats are cut at 44 degrees which means the point where they touch must be sharp.. that angle between them is called the interference angle and must be there for LONG valve and seat life. Through the proper grinding of the valve we must always adjust and maintain a proper valve margin and make sure we do not sink the valve in the head and destroy are proper installed height, also the proper margin thickness insures proper heat transfer of valve to the cylinder head. We use Prussian blue to check for proper seating. When installing valve guides in VW and Porsche heads the only way is to heat the head to 550 degrees have your guides in the freezer for a hour, and just push the guides into place. NEVER use a drift or air hammer to install or remove a guide! I learned these procedures in HS auto shop, College auto shop, VW mechanic school, and aircraft engine building in school in the Navy.

Sat Nov 29, 2014 3:50 pm

The OEM seal back in the 60's and 70's SBC had square cut O ring valve stem seals. They didn't work then so Im sure they wont work on that VW head so leave them there. No harm

Sun Nov 30, 2014 9:58 pm

Helfen wrote: To do a proper three angle valve job we either use angled stones, or angled cutting tools. We may lap the valves afterwards but the angles must be cut first. If all you did was lap valve you would blend the angles between the valve and the seat. The valves are cut at 45 degrees and the seats are cut at 44 degrees

Just reading my copy of the Bentley blue book (1300/1500s).

It says the SEATS are cut 45, (actually 75, 45 and 15 degrees) and the VALVES are cut 44 degrees (actually intake 44 and exhaust 45).

Typo, or was there a change?

And on the "seal" question, could there be confusion with the oil deflector ring which sits under the valve spring cap? It's not a valve seal in the true sense of course - those are large rubber caps which sit over the exposed end of the valve guide to stop excess oil leaking down the valve stems into the head, and are definitely not used on VW heads.

Mon Dec 01, 2014 7:48 am

What happened to the original poster and his rebuilt heads, he must be sitting back watching to see if were all going to have a pissin match about who used o rings seals and who used aftermarket umbrella seal in the 60s and 70s. :lol:

Are you taking the heads apart yourself to see if they did a proper job? If you are, please remove the seals. Check for valve guide clearance and you may as well blue the seats and see where the valve is seating. As the other fellow said check valve stem height too. These are all things you can check without any sophisticated tools.

Mon Dec 01, 2014 10:26 am

Here I am, thanks for all the replies, been busy with kids and stomach bugs all weekend. When I took my heads to the shop, I bought new springs, keepers, and valves. These are the seals I got from Napa http://www.napaonline.com/Catalog/CatalogItemDetai...436505986. Just a square edged O-ring. My parts book calls them, as Rob said, an oil deflector ring 113 109 619. The machinist had slipped them on last, on top of the keeper so it took all of fifteen seconds to remove them. I picked up a spring compressor a couple of months ago, so I think I will check the seats on the valves with the Prussian blue. I got the heads for free and bought the valves and hardware in the classifieds pretty cheap. The machine shop did a great job cleaning and beadblasting them. He only charged me $85 for all of his work. He said it would take him a week to finish them and after six weeks or so I went and asked him if he could finish by the next week. He called me two days later and said they were done. Like I said, I noticed some other cylinder heads had the dye on the seat and mine didn't. It made me curious. Casey

Mon Dec 01, 2014 10:31 am

diablosandwich wrote: Here I am, thanks for all the replies, been busy with kids and stomach bugs all weekend. When I took my heads to the shop, I bought new springs, keepers, and valves. These are the seals I got from Napa http://www.napaonline.com/Catalog/CatalogItemDetai...436505986. Just a square edged O-ring. My parts book calls them, as Rob said, an oil deflector ring 113 109 619. The machinist had slipped them on last, on top of the keeper so it took all of fifteen seconds to remove them. I picked up a spring compressor a couple of months ago, so I think I will check the seats on the valves with the Prussian blue. I got the heads for free and bought the valves and hardware in the classifieds pretty cheap. The machine shop did a great job cleaning and beadblasting them. He only charged me $85 for all of his work. He said it would take him a week to finish them and after six weeks or so I went and asked him if he could finish by the next week. He called me two days later and said they were done. Like I said, I noticed some other cylinder heads had the dye on the seat and mine didn't. It made me curious. Casey

Those seals are not the umbrella seals I thought you said were installed. One thing to remember is that the engine rebuilding gasket kits from VW never had a valve seal.

Tue Dec 02, 2014 6:45 am

Nice to hear from you and glad you tore them down. You will sleep much better after you check them thoroughly yourself

Tue Dec 02, 2014 6:46 pm

He put the valve seals on the end of the valve stem. does he put his undies on his head too

I think they go between the keeper and the guide? correct
Or are they not even needed? they were discontinued because they usually do nothing and fall off and get stuck in the oil screen

I read a few threads and some said not to use them. I agree

In my Bentley book it says to use Prussian Blue on the valve and seat and rotate to check for perfect sealing surface. that is still good method, except no need to twist, just "pop" the valve

Is this something that has to be done? no, my arrogance allows me to believe I am infallible, no need to check my work, but everybody else is a moron, so yes
:wink:

DJ said fill port with water and shoot compressed air around the valve, that's a cool trick. :D

Tue Dec 02, 2014 8:24 pm

[quote="modok"]He put the valve seals on the end of the valve stem. does he put his undies on his head too

:lol: :lol:

Thu Dec 04, 2014 10:49 pm

Apropo of nothing, but I've never seen, heard or read about using prussian blue on valve seats...that's a primary reason for lapping (ie inspect uniformity of sealing surfaces).

Fri Dec 05, 2014 10:10 am

Dr OnHolliday wrote: Apropo of nothing, but I've never seen, heard or read about using prussian blue on valve seats...that's a primary reason for lapping (ie inspect uniformity of sealing surfaces).

Well now you have...get your Bentley book out!

""In my Bentley book it says to use Prussian Blue on the valve and seat and rotate to check for perfect sealing surface. "

Fri Dec 05, 2014 1:18 pm

I dont have a Bentley book, but this makes me question the competency of the book's authors. I have Motors Manuals from the 1940s to 1970s, hot rod books out the ying yang, 50 years (serious hobbyist) experience, brother worked in an automotive machine shop....and this is new to me.