924Board.org

Paul · Posted: Sun Jan 30, 2022 7:34 am Post subject:

Let me know if you do this. I live nearby and can provide a Porsche for the laps.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

safe · Joined: 18 Mar 2017 Posts: 699 Location: Sweden

Mike9311 · Joined: 14 Dec 2004 Posts: 1798 Location: Chicago-ish

That would be neat to meet up at the Indy race and Paul you are awesome.

Need to see what is going on then.

Cedric, I went with the big one initially just because it was the one everyone was using for the CIS-E version. Digging through the massive Pelican thread on FrankenCIS does reveal another 6 cylinder CIS-E option were you just block off two lines. I've been shopping around for one of those as well. Of course I could move back a step or two especially if I am running late into Spring with everything

The CS had a knock sensor on the block but he wasn't using it at the time. My memory is weak on all that discussion you, Dan, and others had back then regarding knock sensing. I seem to remember some had success while some didn't so much

I am just going to play it slow and safe. Get the car running. Feel everything out while hopefully collecting some good data.
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car

daniel · Joined: 18 Jun 2009 Posts: 686 Location: Sydney, Australia

I am in the process of rebuilding the engine in my race car. It is NA. I have presently been running a fairly standard turbo head (standard valve sizes) and want to rebuild with bigger valves. Can you tell me the source of the valves you are using along with the rest of the hardware? (seats, guides, collets, retainers etc)

Cheers
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Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet

Mike9311 · Joined: 14 Dec 2004 Posts: 1798 Location: Chicago-ish

daniel · Joined: 18 Jun 2009 Posts: 686 Location: Sydney, Australia

Thanks for the explanation Mike. Can you give the p/n of the valves you are planning to use?

Thanks
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Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet

Mike9311 · Joined: 14 Dec 2004 Posts: 1798 Location: Chicago-ish

F1074 42mm
F1996P 38mm

There is a 46mm which I bought but it really should be reduced to a 44mm. You need to be utilizing a bigger piston for clearance and shrouding reasons.

If it all works out, I'll likely offer a run of standard location guides as well as seats.

The proven spring choice (on one car anyway ...Gegge's) is PAC-1233 from what I know in my notes

However, I am going to another spring. Once tested I'll let everyone know that option. The goal is to capitalize on the lighter valves and other components.

Valve stem cap choice below but keep in mind these are one thickness only. I may make caps of varying thickness that can be fine tuned by lapping for setting cam / tappet clearances. This can also be done during the sizing of the Ferrea stem heights if you are good and careful.

Manley Wear Cap / Valve Stem Cap
42254
6mm / .2360" Stem
.275 Minimum Tip clearance amount needed before retainer top from top of valve stem
_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car

Mike9311 · Joined: 14 Dec 2004 Posts: 1798 Location: Chicago-ish

Groove progress I mentioned earlier. Remember these are on fake stems so far

Improved groove dimension. This looks better too. Makes more sense that the radius center is out in "space". It looks crappy because I used a black marker to try and imprint the valve lock contact area. It was still wet due to impatience on my part.

Original pic I have on page 1 shows that the groove was too large. It necks down the stem thus weakening it. Remember its only 6mm to begin with! Working on the fixture now to groove a real valve. I want have a fixture in the machine that allows quick valve swapping while holding a few 'tenths' (0.0001-2"). Would be ideal anyway

_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car

Mike9311 · Joined: 14 Dec 2004 Posts: 1798 Location: Chicago-ish

Been a rough few weeks fighting some sort of cold that is rolling through our house. Back at working on this while wrenching on the '82 as well which also has more progress to report.

Super flexible mounting configurations for the uprights currently shown connected to base pieces that can fit any of the slot configurations of the four milling machines, CNC and manual, in the shop. If needed these pop off and it can then be bolted to a plate (uprights also threaded from underneath). Ultimate goal is cnc porting in the same fixture. Reaming for +size guides, offset guide drilling (if I still pursue this course), seat install and machine, flycutting, and porting. Of course 924's only

. Already have 95% of the tooling for the seats and guides. Just making up a mating driver for the seat cutter. Too easy for me to make. Real chips about to fly! Its like a step back for the proper work-holding will allow for faster and larger steps forward

_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car

kondzi · Joined: 02 Jul 2018 Posts: 494 Location: Poland/EU

woohoo

I plan to do dual port plugs by myself in my 911 on my manual mill, but it's peanuts compared to your plans

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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded)

Mike9311 · Joined: 14 Dec 2004 Posts: 1798 Location: Chicago-ish

kondzi · Joined: 02 Jul 2018 Posts: 494 Location: Poland/EU

Mike9311 · Joined: 14 Dec 2004 Posts: 1798 Location: Chicago-ish

little update

Reamed the guide bores in the head to accept a custom oversized guide just to erase the PO's head work in this area. Nice clean slate to start

First exhaust guide being machined. Will tweak design further from here. sub 6mm bore is true with the eccentricity being an optical allusion. Will be final reamed after installation. Might nix the offset intake just to save time. Its also pushing the limit of the valve seal since there is only so much you can offset. Still thinking about it.

Also confirmed the tappet bore center shares guide bore center as one would assume

_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car

Mike9311 · Joined: 14 Dec 2004 Posts: 1798 Location: Chicago-ish

First 6mm stem exhaust guide installed. Also note how PO of this head 'over ported' the top side by the manifold sleeve. Will need to make custom opening and sleeves to deal with this or else I have a sleeve edge exposed.

_________________
1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car