fasteddie313

I'm struggling to keep a classic Porsche 931 on the road on a low budget and can't see dropping $200 on a rubber...

Do any of you know where to get them at a reasonable price? Is there such a thing as a good used diaphragm?

Mark Houghton

Pelican shows them for $192 (hey...that's a full $8 less than $200!).
Or, you may try these guys: http://www.sunsetimports.com/

As far as a used one; nothing wrong with that (after all, we all have used diaphrams in our WG's). If in good condition and the price is right, you could get who knows how many years out of a used one. But finding one....?

Or, you can drop a little more change and go with a Tial WG, unless you must have originality.

fasteddie313

Man this thing is really hurtin me...

This is where I'm at..


Absolutely love this drill press, 1955 CMan with variable speed, 300#s, milling quill, etc.. $75 garage sale..


Irwin Hanson easy outs rock, I'm going to try them after I can get/borrow a torch for heat..


I don't think the studs were especially hard steel, USA HSS drill bit went all the way through em like butter, set my depth stop to inserted stud length as not to drill into the cast, low speed, WD40, also trammed the chuck to the table right beforehand with a right angle and a very straight snap on phillips screwdriver.Also ground flat - center punched the broken stud ends the best I could by eye in the first place..

I don't fancy disassembling the WG any further, there is some small play in the valve stem but I believe it's serviceable..

Mark Houghton

Hell of a deal on a nice vintage drill press, a must-have in any shop. My Craftsman burned up in my garage last year (along with you can guess what).
So back on topic: That WG looks like it was rode hard and put up wet. Hope it's worth all your effort, and hope that you don't find the valve guide leaks too much (if so, it will be sluggish to open at the correct bar). Have you been running with it, or just found a deal you couldn't pass up?

fasteddie313

I've been running with it the whole time I've had the car. Never had a boost gauge and supposed to be a .45 Bar spring. It stuck closed on me and I hit the overboost fuel cut on one of my first WOT runs after getting the car running but was fine after, I think but don't really know with no gauge.. The car is getting a boost gauge immediately after the WG is done..

I tore it down because I found it to be leaking while installing a MBC, after fabricating a one off FMIC setup + BOV, and building a hybrid turbo all in one go. A lot of work since the car ran last and now the WG on top of it..

How much valve guide leak is too much leak?
Do you think turning an O ring seat into the valve stem as high as possible on the lathe would be a good idea to really seal it?

Mark Houghton

How much is too much? Sorry, can't answer that one. Even a brand new WG will leak some (the o'ring is an interesting idea, though). Even when bench testing these with regulated air pressure, they take more pressure to open than whatever spring you're using (.45 bar in your case) for two reasons: leaking, and the need for exhaust back pressure which facilitates the opening. The last time I tested a stock WG on the bench (my guide was leaking pretty good) I think it took around 15-16 psi to open against a .8 bar (12.5 psi) spring. There's also a gasket (probably asbestos) between the two halves of the WG that can also spring a leak (mine did), so I eventually just bought a Tial and never looked back.

Somewhere years ago, either here or on Pelican, someone posted information about machining a new guide. If you have a lathe and the proper materials, why not just make a new guide?

fasteddie313

My lathe is an old clunker from the late 1800's, headstock bearings are a bit sloppy, only have a 4 jaw chuck, no compound just carriage and cross slide, no chuck for tailstock for drilling/reaming and tailstock quill lock is broken, feed screw on a belt so no threading, only 1 chuck speed (fast) and 1 feed speed (slow), I have a bunch of boring bars and a collet type bar holder with eccentric collets but I've not yet fabricated a T nut setup with a correct spacer to put the holder on the cross slide high enough to get the bars on center..

Frankly I just don't have what it takes to make a new bushing that long accurate enough..

Turning a simple O ring seat into the valve stem sounds very doable though or maybe turning an O ring seat just inside the top end of the brass bushing would be a better idea so as to take the chance of ruining the bushing vs ruining the valve..

I could grind a tool for either of those operations easily enough and just increase the depth of the seat until it fits well.. No real accuracy required other than taking an hour to indicate the work in the chuck to center..