Hey everyone,
I'm currently rebuilding the engine on a 1976 914 2.0. It has the original detuned GC coded engine that came with California emissions D-jet, air pump and catalytic converter.

My goal is to keep the engine fairly original while doing any worthwhile upgrades in the process. I would like to keep the D-jet fuel injection if possible but I don't mind ditching the air pump and cat as I don't live in a state that has strict emissions laws.

Here is what I am thinking so far:
-Reconditioned Stock 2.0 heads (New valves, new guides, cut seats, CC matched chambers, spark plug inserts).
-Stock 71mm crankshaft w/Stock connecting rods.
-96mm P/C set from Aircooled.net (Cast Piston & Biral Cylinder Set, 96mm x 71mm) Has anyone used these? Are they any good for the $360 price?
-Raby 9590 Cam Kit.

I'm guessing that the original detuned california D-jet setup is going to be useless with the big bore pistons/upgraded cam profile, is this correct? If so can I retrofit the computer from a U.S. 1973 spec/ROW/euro spec computer with my system? How much of the cali emissions 75-76 F.I. components jive with the earlier systems? I'm already planning to buy a new D-jet wiring harness and I don't mind tuning a system to work properly (as close to "properly" as I can get with a 41 year old analog computer running an engine it wasn't designed to run)
Any advice is appreciated and thanks in advance!

D-jet does not play well with lumpy cams

only cam i ever got to work well was the WebCam 73 grind

half point CR increase is good = euro spec 914 2.0 ("S") =- 9:1 is dicey for pump gas on a type-4 cuz the heads run hot .... & that can mean detonation

also - do a 4mm throttle body over bore - does wonders for midrange power - used to be a guy in SoCal who did these for us (did 2 for me, with euro p&c 2.0s) - iirc his name was Ed Mazula - advertised in Pano, etc - I suspect the T4 guys on Samba.com will know of him &/or can guide you

basically - you can swap most any D-jet cpu for any other - but you cannot "rewire" the D-jet cpu - unless maybe you are a PhD engineer with a full laboratory of test eqpt & dynos to play with for free for a couple years or so - or have a few hundred bundles of G-notes to pay someone who can single-handedly completely re-engineer what the Bosch/Porsche engineering teams did

google is your best friend
https://www.google.com/search?q=Ed+Mazula+t...-8&oe=utf-8
- old threads
http://www.914world.com/bbs2/lofiversion/i....php?t6199.html
http://forums.pelicanparts.com/porsche-914...ket-brains.html

lighten the flywheel to Bontempi HPH specs:

my Bontempi lightening notes, measured from the FW as he prepared it, show: 3 steps - scribe dimension "A" across the back of fw = 9 3/4 in, "B" chamfer 45 degrees from this diameter toward the ring gear, finally "C" thin the ring gear to 0.55 thickness - pretty simple stuff

- the internal face and the step both have to be machined to the correct step specs - i'm sure you can find those on myriad VW sites as well as elsewhere on World & Pelican - this is an old rodeo event, played out many times before

my Bontempi notes on internal depths, as he prepared it, show: A- ring gear face to clutch mount face = 8mm, B- clutch mount face (step) to clutch surface = 22mm, C - clutch surface to flange surface = 2mm, D - on the backside, crank flange surface to backside of clutch surface = 5mm

finally - anytime you machine the internal surfaces, per Rich, you have to put a 0.065 washer under the T.O. lever ball to compensate for the fact the clutch now sits deeper & further away from the T.O. brg

Bontempi won a lot of trophies using this flywheel formula - suggest you ask him personally about it's durability

The 73' setup is a "fooled" 1.7 system with a unique MPS and head temp sensor w/resistor. Those two items are difficult to find and if you do, expensive. Your MPS and head temp is the same as 74' so use ECU, injectors,single wire cold start thermo switch, and harness from a 1974 car.
I ran this setup in my 76' along with euro pistons and had a very fast and cooler running 2.0 and still easily passed Cali. smog every time @ 28-30 MPG.
My air pump was gutted and EGR was let's say "stock appearing"
Late CAT equipped cars came with a sister rev limit module mounted to battery tray. It will be eliminated with the 74' harness so don't forget to change distributor rotor to rev limit type.

My 2276 runs 10:1 compression on 98 RON pump gas with zero detonation issues.
so it can be made to work if you can run premium fuel.

"D-jet does not play well with lumpy cams".

I disagree.

I have a raby cammed 2056, 9:1 cr. It starts and idles perfectly, gets 28mpg and pulls strong to 6k. Stock Djet with the exception of a readjusted mps.

I'd backdate the exhaust system as well to a 73-74 2L 4 pipe system and muffler. the 2 into 1 shorty headers from 75-76 are not optimal.

The "de-tuned" D-jet wasn't responsible for any real amount of the difference between the 73 and 76 2.0 power ratings. The exhaust was basically all of it. Replace the lousy 75-76 exhaust with a 73-74 style, or with real headers if you don't need any heat or defog.

--DD

I would consider finding a set of 1.7 rockers with the 8mm adjuster screws, they are the same ratio as the 2.0 so no difference there but you can buy the original 8mm porsche swivel foot adjusters from say Pelican and this will add many miles to the life of your valve stems, also spend a lot of time setting your valve geometry, it pays off on a type IV motor.

I also re-machine Bus, Vanagon, FI throttle bodie's for type I and 914 throttle bodies if you need any advice there.

Phil