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Group -- I am looking for some help with replacement valve guides for S4 heads. I've read the posts on the topic, but some questions remain. I've added a poll here, as it seems to be fashionable. Please also post your comments and advice. Best, Tuomo
FWIW, I ordered a set of factory valve guides (944.104.327.51, 6.95 each) to discover that they were 0.010 over (IIRC, it may have been less than that). Greg showed me the wobble that would allow and said, 'too big' and I returned 'em. Turned out that my intake guides were good and they only replaced the exhaust valve guides. With what, I do not know.
THE PHOSPHER BRONZE GUIDES ARE EXPENSIVE BECAUSE THEY USE A VERY HIGH PERCENTAGE OF COPPER IN THE MATERIAL AND AS YOU MIGHT KNOW COPPER PRICES ARE WAY UP. WE RECOMMEND THEM ONLY FOR A RACE ENGINE THAT IS GOING TO BE REBUILT ON A REGULAR BASIS BECAUSE THEY HAVE A HIGHER WEAR RATE DUE TO THEIR "SOFT" COMPOSITION. THEY HAVE THE ABILITY TO TRANSFER HEAT BETTER THAN ANY OTHER MATERIAL. BECAUSE OF THE HIGH PERCENTAGE OF COPPER AND THE VERY LIMITED QUANTITIES WE MAKE THEM IN, THEIR PRICE IS CONSIDERABLY HIGHER. THEY ARE DEFINATELY NOT FOR A STREET ENGINE AS YOU WOULD NOT GET SATISFACTORY MILEAGE FROM THEM.
THANK YOU
PETER WIGBELS
GENERAL MANAGER
-----Original Message-----
From: ptuomov
To: siindustriesinc@aol.com
Sent: Fri, Jun 26, 2009 6:35 am
Subject: Re: A question about your products VG 3058/00 and VG P3058/0
Thank you for the info. What do you mean by "race use?". Is there a
reason (other than the outragous price) not to use these racing valve
guides in a street car? If not, in which way are "racing" guides
superior relative to the standard guides?
On 6/23/09, siindustriesinc@aol.com <siindustriesinc@aol.com> wrote:
> TUOMO,
>
> ?????? THE VG 3058/00 ARE $4.99 EACH. THE PHOSPHER BRONZE VERSION IS
> PRODUCED IN LIMITED QUANTITIES AND IS ONLY FOR RACE USE. THE PHOSPHER BRONZE
> IS $13.95 EACH. I HAVE THE SEALS ALSO. THEY ARE $2.00 EACH IN VITON.
>
>
> THANK YOU
>
> PETER WIGBELS
>
> GENERAL MANAGER
>
>
> -----Original Message-----
> From: ptuomov
> To: siindustriesinc@aol.com
> Sent: Mon, Jun 22, 2009 5:32 pm
> Subject: A question about your products VG 3058/00 and VG P3058/0
>
>
>
> Dear Sirs --
>
> How are the following two valve guides priced?
>
> Guide: Porsche: 928S4; 944S 4V IE Std 0.2758" I.D. x 0.4355" O.D.
> x 1.730" Long VG 3058/00
> Guide: PB: Porsche: 928S4; 944S 4V IE Std 0.2759" I.D. x 0.4355" O.D.
> x 1.730" Long VG P3058/0*
>
> I am interested in a set of 32.
>
> In addition, I would need valve guide seals if you have specific seals
> that are appropriate for these guides.
>
> Best, Tuomo
>
The price of raw copper is probably not an explanation why tiny little piece of special high-copper bronze alloy costs $14 and a similarly tiny piece of another special bronze alloy costs $5. Especially since the price of copper has collapsed over the last twelve months. ;-)
Although the pricing explanation doesn't make much sense, I think it makes sense for me to buy the $5 guides from SI Industries.
Since the beginning of time for the making of valve guides I have used the JM3-15 tin bronze produced locally here in Sweden by the Johnson Metal Company. See page 9 http://www.johnson-metall.com/img/file.php?id=60824
However long time experience has told me that cast iron valve guides do have the longest life span. I had my wife´s old Volvo apart and after 720.000 km (450.000 miles) no wear could be seen on the cast iron valve guides. For high performance engines bronze valve guides is preferable because of better sliding properties and heat transfer.
Åke
SI Valves can make em in any size (ID/OD/length) you want for $10 or less, each.
I had them make custom oversize for my Impreza (whose OEM guides were too "loose" and actually got pounded out of the head at 120k miles) for $5 each.
Whats the gain and drawback of cutting guides short where they protrude into the intake track?
If it is a gain it would be to make it easier to grind out the port. People also say improved flow but that is questionable. The drawback is more rapid wear of the guides, the valves and the valve seats.
During all my years as cylinder head porter (started as an amateur in the 1960´s) I have hardly never cut the guides short where they protrude into the port. It is better to remove the guides before start grinding. It is also important to maintain a good support for the guides so they won´t come loose during engine operation. The solution is to grind the port with an streamlined "nose" in front of the valve.
Åke
SI Valves can make em in any size (ID/OD/length) you want for $10 or less, each.
I had them make custom oversize for my Impreza (whose OEM guides were too "loose" and actually got pounded out of the head at 120k miles) for $5 each.
When performing cylinder head work it is a huge advantage to be able to make your own valve guides. As Rocket points out quite often new guides needs to made slightly oversize in order to make sure they will have the correct interference fit and stay in place and won´t come loose during engine operation. For more advanced jobs, where in order to make room for oversize valves the valve guide holes in the cylinder head have to be machined in a slightly different tilted angle, the only solution is to make custom valves guides with a larger outside diameter.
In the old days car manufacturer like BMW supplied oversize spare valve guides in order for the mechanic to turn them down for the correct fit. Nowadays they supply valves with oversize stem diameter for the mechanic to ream or hone out the guides for the correct clearance.
When replacing valve guides in an aluminum cylinder head, the head needs to be heated quite a lot (230-240 C or 450-460 F) in order to expand sufficiently to get the guides in easily. In order to prevent galling I always put some Molykote Paste G-n Plus on the outside of the guide.
Åke
I have just recently manufactured and installed bronze valve guides in my BMW BIg Six racing cylinder head I am working on. To make room for the extra large 50mm intake valves, I was forced to change the tilted angle of the intake valve by one degree, which means that the valve heads in the combustion chamber become further apart. Machining the bores in the head at a different tilted angle means that the bores becomes larger, in this case from 14mm to 18mm. Specially made valve guides can be seen in the picture. Porting remains to be done.
Åke
I have just recently manufactured and installed bronze valve guides in my BMW BIg Six racing cylinder head I am working on. To make room for the extra large 50mm intake valves, I was forced to change the tilted angle of the intake valve by one degree, which means that the valve heads in the combustion chamber become further apart. Machining the bores in the head at a different tilted angle means that the bores becomes larger, in this case from 14mm to 18mm. Specially made valve guides can be seen in the picture. Porting remains to be done.
Åke
Moving a valve angle requires some serious effort and skill.
It's been fairly obvious, for quite some time, that your skill levels are way beyond that of us mere mortals....
Mr. Brown, I know your 928 skills are very impressive.
Here is the combustion chamber of a ported two valve cylinder head.
Note the special made intake valve guide for 8mm valve stem and the bronze insert seat ring for a larger 48mm valve.
Åke
06-22-2009 | 07:10 PM
Valve guide questions
