87-89 Guides Availability via Pelican

[vreference]

Oh nuts. So I just heard back from the machine shop on my heads. Looks like I'll be buying $300 worth of valves while I'm at it here. I left a couple pages of the Bently manual with them and they called today and requested the Standard size Valve guides (I told them I'd like to buy the parts myself from Pelican and I'm in no hurry.)

Bently reports 13.060 as Standard OD and 13.260 and 1st Oversize.

From what I can see pelican only carries 13.08OD which is listed as 1st OD and 13.260 which is listed as 2nd Oversize. I suppose this isn't an issue - they all need to be machined anyway I take it and I suppose I'll get the 13.08 guides.

I only see 930-104-321-53-M105 listed for 87-89 and it's listed as an Intake. Does anyone know if they are the same part for Int and Exh? The part material is not listed either?! I've heard phosphorus bronze is the only way to go but Canyon sells both so I'm a bit worried.

Here's some valve-play action for those interested.

[cgarr]

What do they show for the guide installed height? That may be the difference if the intake has no shoulder. My records show that number being a Bronze guide and at 4.75 that would confirm that. I show you can use 93010432151 Phos Bronze guide for both.

Those first over size are really "first replacement" not much left to machine if you are trying to go for guide concentricity, by the time you square it up you may not have the proper interference.

[brighton911]

Nice action shot of a guide that must be darn near egg shaped. I was not sure how much force was needed to rock a valve stem, video helped. Good luck on the re-build.

[Dynamohum]

Originally Posted by vreference

Oh nuts. So I just heard back from the machine shop on my heads. Looks like I'll be buying $300 worth of valves while I'm at it here. I left a couple pages of the Bently manual with them and they called today and requested the Standard size Valve guides (I told them I'd like to buy the parts myself from Pelican and I'm in no hurry.)

Bently reports 13.060 as Standard OD and 13.260 and 1st Oversize.

From what I can see pelican only carries 13.08OD which is listed as 1st OD and 13.260 which is listed as 2nd Oversize. I suppose this isn't an issue - they all need to be machined anyway I take it and I suppose I'll get the 13.08 guides.

I only see 930-104-321-53-M105 listed for 87-89 and it's listed as an Intake. Does anyone know if they are the same part for Int and Exh? The part material is not listed either?! I've heard phosphorus bronze is the only way to go but Canyon sells both so I'm a bit worried.

Hi, I just went through this myself,

I would highly recommend using a shop that has experience working on Porsche heads, as they can be easily damaged by improper removal and installation of the guides. The guides have an interference fit, when doing them properly the heads are heated and the guides cooled prier to installation. Pressing the guides into cold heads with excessive force of an arbor press can excessively stress the head to the point cracking of the guide boss. I’m not keen on how some North American shops drive out the old guides or how they install the new ones. These methods might work fine for cast iron heads, but I would not recommend doing it that way not for ours anyway. Stick to shop that has the proper tooling and experience with our heads.

Even when the guides are removed properly there will be a small amount of material galled from the bore the guide came out of. The bore (hole) that the guide fits into needs to be reamed to size, this involves removing a small amount of material to clean up the bore to required size needed for the interference fit of the new guide.

This is typically why first oversize guides are used. That said a shop with experience will have the proper tooling to size the bore and to finish fit the valves to the guides to spec.
The I.D. of the guide is 9mm but will shrink slightly from the interference fit of the guide to head transferred to the I.D. of the valve guide.

Re: the part fitment
I asked the same question when ordering my guides from here and was told that there is a mistake in the Pelican parts catalog. Check with your order clerk and they will verify this.
The same guides are used for intake and exhaust you can go with the any of the following parts, see below, your choice.
You will find everyone has there own opinion on which to use.
My 2 cents wort, in a N/A build the brass is fine, I got a 140K out of my old ones, new ones will probably outlast me.
For a turbo or in a racing application spend the extra and go with the phosphorus bronze. Or you can mix and use brass on the intakes and the phosphorus bronze for the exhaust.
Oh and a tip on the choice of valve seals. The Viton and Teflon. The Teflon ones are typically used in a racing application as they allow a more lubrication through to the valve stem and guide, they are however a pain to install. The Viton are an OEM style, and work fine for a street car and if emissions are at all a concern go with the Viton, because you don't want the extra oil contaminating your emission readings.


930-104-321-53-M105

Valve Guide, (1st oversize - 9 x 13.08mm), Intake 911 (1987-89)
Brand: Canyon [More Info]

$4.75

930-104-321-50-M105

Valve Guide, bronze (1st oversize - 9 x 13.08mm), Intake/Exhaust 911 Turbo (1976-89)
Brand: Canyon [More Info]

$5.25

930-104-321-50-M230

Valve Guide, phosphorus bronze (1st oversize - 9 x 13.08mm), Intake/Exhaust 911 Turbo (1976-89)
Brand: Domestic Aftermarket [More Info]

$8.25

Good luck, hope this made sense and helps?