CIS to ITB EFI conversion

[dannichols1474]

I received the new gas struts for my rear decklid and front hood today.

The new struts for the front hood worked fine.

The new strut for the rear decklid wouldn't hold up the decklid. I re-installed the Rennline mechanical strut I had purchased last week, adjusted the hood stop buffers and then the rear decklid worked fine also.

Next I pulled out the old rear decklid gas strut and compared it to the one I hard just received and the part numbers were different. I had forgotten that there are 2 versions of the gas strut - a 300N standard version / 911-512-331-01 and a 600N heavy duty version / 911-512-331-02.

My car has 1 strut on the rear decklid, so it needs the 600N version. Other 911's that have 2 struts on the rear decklid can use the 300N version.

For me, ever since Pelican Parts updated their online ordering website a few years ago I have found it more difficult to find the correct parts for my 75 Carrera. The old version of the website would list both versions of the strut and a description of which version was used in which application. The current version of the website lists just the -01 version of the strut until I clicked on the view catalog button and then both the -01 and -02 versions were displayed. Frustrating.

[Hi_Fi_Guy]

Had similar issues recently with parts for my 911 and Cayman. The new system makes it challenging to know if you are ordering the right parts or not.

[dannichols1474]

Originally Posted by dannichols1474

I have learned a lot of valuable information from these forum pages - the most recent being that I can download Porsche parts catalogs (referred to as "PET" in forum threads) by model and year range (eg. 911 1974-77). I just went to Porsche.com, from Menu select Services, then select Classic Services & Parts. Scroll down the page to "-Genuine Parts" then select "Porsche Genuine Parts Catalogues". From Choose Catalogue select the model and year range, then press the "Display" button and boom your pdf format catalog opens. Thank you PP forum members!

I did some part number searching in the Porsche part catalog that I had downloaded (see above quote) to get a better understanding of when Porsche used the -01 300N rear decklid strut versus the -02 600N rear decklid strut.

Since the 74-77 911 / 911S, 76 912E, and 74 Carrera have a lighter rear decklid, those models use a single 911-512-331-01 (300N) "gas pressure spring" (strut).

The 75-76 Carrera has the heavier (whale tail) rear decklid and uses a single 911-512-331-02 (600N) strut, while the Carrera with factory air conditioning installed (the A/C condenser is mounted to the underside of the decklid) uses two 911-512-331-02 (600N) struts to handle the extra weight.

So my frustration in ordering the wrong part number from Pelican Parts is self inflicted.

Always check the factory parts catalog for the relevant parts numbers!

[phelix]

As others have already said - great thread and thank you for sharing the knowledge and experience gained.

One question - have you considered a 2nd wideband sensor for the other bank? I have a twin plug 3.5 engine that the PO did with only one sensor; adding one for the other bank helped with low speed part throttle drivability as it accounts for minute variations between banks. Just a thought…

[dannichols1474]

Originally Posted by phelix

One question - have you considered a 2nd wideband sensor for the other bank? I have a twin plug 3.5 engine that the PO did with only one sensor; adding one for the other bank helped with low speed part throttle drivability as it accounts for minute variations between banks. Just a thought…

Hi phelix,

Yes, the thought has occurred and I have an O2 sensor bung on the 4,5,6 bank collector. I just last week went out for a low load (TPS around 2.5%) auto tune session to tweak in the VE table values at 1500 rpm and above and the car runs more smoothly now in the low speed part throttle region.

Thank you for sharing your experience on adding a second O2 sensor to the ECU, I'll keep that in mind.

[dannichols1474]

I saw a forum thread earlier this week about the look of the 74-89 911 rear bumpers with the mandated 5 mph crash bumpers with the large US style bumperettes versus the look of the Euro bumperettes versus the shaved bumper and it got me thinking about the look of my 1975 911.

75 911s (Duane) had posted a photo of his 75 911S with a smooth rear bumper and I thought "I want that too". So I searched the forum for his thread, which I have copied the link to below, and found on page 10, post 194 thru post 198, he goes thru the process of modifying his rear bumper, so I decided to try doing the same with my rear bumper.

http://forums.pelicanparts.com/porsche-911-technical-forum/878569-born-75-me-my-new-911s-10.html#post9479788

My 75 rear bumper as is:



I don't have access to affordable TIG welding so I used JB Weld to fill-in all of the unneeded holes in the bumper. I started by covering the backside of the hole with Gorilla tape, then applying JB Weld to the front side filling the hole not quite to the surface.

I fabricated the same type of slotted bumper mounting brackets but I made the slots open to the sides so I can remove / replace the M8 x 20 carriage bolts.



















Since the height of my mounting brackets is the same as the thickness of the rubber spacer that goes at the front of the bumper strut, I deleted the rubber spacer and did not have to shorten the length of the bumper struts in order to position the bumper properly on the car.

On Monday, I take my bumper to the local fab shop to get the slotted mounting brackets TIG welded to the inside of the bumper. Then I can remount the bumper and check for proper fit.

Then I will remove the bumper, sand the JB Weld areas, apply a thin coat of Bondo, sand the bumper smooth, then take the bumper to the body shop to get it painted GP White (code 908).

[dannichols1474]

I got the bumper mounting brackets TIG welded to the inside of the bumper yesterday. The JB Weld and Bondo I had applied handled the heat of welding, the original paint near the weld locations was cooked, so I set about sanding off most of the original paint, then applying another skim coat of Bondo to the JB Weld filled holes and block sanding. When I was satisfied with the finish, I thoroughly degreased and dried the inside of the bumper then sprayed gray primer. After a 1 hour dry, I flipped the bumper over and used jack stands (with folded microfiber clothes taped on to protect the fresh paint on the inside of the bumper) to hold the bumper off the floor, thoroughly degreased and dried the outside of the bumper then sprayed 3 coats of gray primer (first - light dust coat, then 2 medium coats).

Next, off to the body shop to get the outside of the bumper painted in GP white.

TIG welded mounting brackets





Bumper prior to block sanding Bondo:

[dannichols1474]

I got the bumper back from the body shop today and installed it. The smoothie rear bumper looks good and by removing the bumperettes (7.5 lbs each), rubber molding strips (0.5 lb each) and converting from the US shock absorber bumper struts (4.5 lbs each) to the Euro hollow tube bumper struts (1 lb 9.5 oz each) I trimmed 21.8 lbs off the tail end of the car.

Bumper mount as installed:



Original rear bumper:



Smoothie rear bumper:



Thank you Pelican Parts forum for the inspiration!

[rwest]

That came out real nice!

[Tony V]

That's one smooth rear end

[al lkosmal]

Looks great and reduces the weight where it counts!

[dannichols1474]

This forum thread is long. Below is an updated table of contents to help you navigate thru it.



CIS to ITB EFI conversion: pg1 post 1-20, pg2 post 21-27

Brake conversion / weight reduction: pg2 post 28-30

Wiring improvements: pg3 post 41-42

Crankcase tear down: pg4 post 62-66

Heads tear down: pg4 post 68

Head stud removal: pg4 post 69

Engine wiring harness: pg4 post 72, 76

Parts cleaning / refinishing: pg5 post 81, 90, 96-99, pg6 post 100-105

Distributor modifications: pg6 post 106-107

Engine compartment seals: pg6 post 109-110

Engine lid seal: pg6 post 115

Rod and chain holder tools: pg7 post 126

Convert to moisture resistant connectors: pg7 post 129-132

Ground connections: pg7 post 136

Updated wiring diagrams: pg7 post 139-140

Piston weight: pg8 post 141

Engine air baffle modification: pg8 post 142

Updated sprocket supports: pg8 post 146-147

Piston / cylinder assembly: pg8 post 148-150

Fan, fan housing, alternator assembly: pg8 post 151-152

Deck height and compression ratio: pg8 post 153

Ignition timing set up - more info: pg8 post 154-155

Rod weight and piston/cylinder assignment: pg8 post 160

Crankcase clean and assembly: pg9 post 161-178

Valve train mock up: pg9 post 179

Piston to valve clearance: pg10 post 181

Engine assembly: pg10 post 182-194

Engine / transaxle installation: pg11 post 202-207

Camshaft break-in: pg11 post 209

O2 sensor controller calibration: pg14 post 263-266

Camshaft replacement: pg14 post 267-275

Final headers / exhaust fabrication: pg14 post 276, pg15 post 287, 292

Dyno tune / test results: pg15 post 295-296

Accel Enrichment Table: pg16 post 304

VE Table discussion: pg16 post 306-313

Rear decklid / front hood struts and rubber buffers discussion: pg16 post 316, 318-320 & pg17 post 322-323

Smoothie rear bumper fabrication: pg17 post 326-328



Hope you find this thread to be helpful.

Good luck with your DIY project!

[RSBob]

The backside looks fantastic. HUGE improvement. Kind of like my old car - except I moved the top of the plate to be flush with the top of the bumper.

[75 911s]

Originally Posted by dannichols1474

I saw a forum thread earlier this week about the look of the 74-89 911 rear bumpers with the mandated 5 mph crash bumpers with the large US style bumperettes versus the look of the Euro bumperettes versus the shaved bumper and it got me thinking about the look of my 1975 911.

75 911s (Duane) had posted a photo of his 75 911S with a smooth rear bumper and I thought "I want that too". So I searched the forum for his thread, which I have copied the link to below, and found on page 10, post 194 thru post 198, he goes thru the process of modifying his rear bumper, so I decided to try doing the same with my rear bumper.

http://forums.pelicanparts.com/porsche-911-technical-forum/878569-born-75-me-my-new-911s-10.html#post9479788

Dan,

The bumper turned out awesome! Of course I'm biased! :-)

[dannichols1474]

My next project for the P75 is converting from the heavy US shock absorber front bumper struts to the hollow tube Euro bumper struts.

I deconstructed the front bumper and valance, removed the fog lamps and removed the windshield washer system (reservoir, pump and tubing back to the dash) - I don't use either of these and I had been carrying around 2 gal of washer fluid for the last 18 years.

The rubber front molding strip on the front of the front bumper is secured by a series of plastic rivets and a plastic retaining strip across the face of the bumper and secured at each end by a Phillips head sheet metal screw. To remove, I took out the screws at each end and then carefully peeled the rubber molding strip off its plastic retaining strip. This reveals the bumper mounting nuts hidden underneath the rubber molding strip.

It took me a bit to figure out the side mounting bolts for the valance are beneath the bumper and that the front valance is not attached to the front bumper like the rear valance is attached to the rear bumper. Therefore, I came to understand that I had to remove the front bumper first (which included detaching the front turn signal lamp housings from the bumper before I could pull the front bumper away from the car), then the valance side mounting bolts were exposed and I could remove the front valance. I also removed the fog lamps from the front valance before I could pull the front valance away from the car.







Next, I replaced the old US style bumper struts with the Euro struts. The Euro struts have an M12 stud at the base of the strut (versus M8 on the US strut) so I used a Dremel tool with a metal cutting bit to open up the slot at the strut attachment point on the body.

I also wanted to pull in (i.e. tuck) the front bumper into the body, so I deleted the rubber bumpers at both ends of the strut which meant I needed to add 3 M12-40mm washers to take up the extra M12 stud length protruding thru the slot in the attachment point on the body. Since the body tub is getting wider from the front end back to the windshield, I had to trim one of the M12-40mm washers to get it to fit.









Next, I mounted the bumper to check fit. I was high on the left side, low on the right side, so I removed the bumper, loosened the bumper strut mounting nuts, remounted the bumper and used a floor jack to persuade the bumper into correct alignment then tightened the strut mounting nuts, then removed the bumper.



Now I could mount the front valance. Once it was tightened into place, I mounted the front bumper, reinstalled the front turn signal lamp housings and tightened down for the final time the bumper mounting nuts. I had installed and tightened down the rubber side accordion pieces to the bumper before the final bumper mounting, so now I connected the accordion pieces to the front fender extensions and tightened the fender extensions to the front fenders and the front valance.

I used a split fork tool to carefully remove the plastic rivets and the plastic retaining strip from the face of the bumper. Then I carefully worked the rubber molding strip back onto the plastic retaining strip. Now I could "pop" the rubber molding strip back onto the face of the bumper by pushing the plastic rivets into their plastic cups in the bumper and secure the ends of the rubber molding strip by inserting the Phillips screw at each end of the rubber molding strip.

Before the front bumper tuck:



After the front bumper tuck (and fog lamps removal):

[Joesmallwood]

Love the bumper tuck. I did this last winter and, to me, it's a much better look.

[dannichols1474]

One last item I have wanted to address with my car is the headlights. Specifically, I have the US spec sealed beam style lamps with the "oversize" trim ring and I have always preferred the cars with the Euro spec H4 lamps, so I decided to make a change.



While I was at it, I decided to try an LED conversion as well so I bought and installed the Rennline EL13 conversion kit. Unfortunately, the car just doesn't look right to me with these lights.



So I decided to buy the Porsche H4 headlight assemblies (p/n 911-631-113-00), the Porsche headlight trim ring (p/n 911-631-141-00), H4 halogen bulbs, small light bulbs, etc. When I got the parts from our forum sponsor I wasn't sure how everything was supposed to go together so a short thread asking for guidance (see link below) yielded a bounty of valuable information including a suggestion to use the thin fender to headlight seal (Porsche p/n PCG-631-115-00 formerly 644-631-115-00). The H4 headlight assemblies fit much better with the thin seals than they did with the thick headlight seal.

http://forums.pelicanparts.com/porsche-911-technical-forum/1171986-headlights-us-euro-h4-question-need-your-help.html#post12381210

Thick seal:



Thin seal - headlight assembly fits better:



I made up some wiring pigtails to bring parking light power to the small light bulbs in the H4 headlight assemblies.





H4 headlights installed with the parking lights on.



US spec to Euro spec headlight conversion completed.

[al lkosmal]

Nice change, Dan.

[dannichols1474]

This forum thread is long. Below is an updated table of contents to help you navigate thru it.



CIS to ITB EFI conversion: pg1 post 1-20, pg2 post 21-27

Brake conversion / weight reduction: pg2 post 28-30

Wiring improvements: pg3 post 41-42

Crankcase tear down: pg4 post 62-66

Heads tear down: pg4 post 68

Head stud removal: pg4 post 69

Engine wiring harness: pg4 post 72, 76

Parts cleaning / refinishing: pg5 post 81, 90, 96-99, pg6 post 100-105

Distributor modifications: pg6 post 106-107

Engine compartment seals: pg6 post 109-110

Engine lid seal: pg6 post 115

Rod and chain holder tools: pg7 post 126

Convert to moisture resistant connectors: pg7 post 129-132

Ground connections: pg7 post 136

Updated wiring diagrams: pg7 post 139-140

Piston weight: pg8 post 141

Engine air baffle modification: pg8 post 142

Updated sprocket supports: pg8 post 146-147

Piston / cylinder assembly: pg8 post 148-150

Fan, fan housing, alternator assembly: pg8 post 151-152

Deck height and compression ratio: pg8 post 153

Ignition timing set up - more info: pg8 post 154-155

Rod weight and piston/cylinder assignment: pg8 post 160

Crankcase clean and assembly: pg9 post 161-178

Valve train mock up: pg9 post 179

Piston to valve clearance: pg10 post 181

Engine assembly: pg10 post 182-194

Engine / transaxle installation: pg11 post 202-207

Camshaft break-in: pg11 post 209

O2 sensor controller calibration: pg14 post 263-266

Camshaft replacement: pg14 post 267-275

Final headers / exhaust fabrication: pg14 post 276, pg15 post 287, 292

Dyno tune / test results: pg15 post 295-296

Accel Enrichment Table: pg16 post 304

VE Table discussion: pg16 post 306-313

Rear decklid / front hood struts and rubber buffers discussion: pg16 post 316, 318-320 & pg17 post 322-323

Smoothie rear bumper fabrication: pg17 post 326-328

Front bumper tuck: pg17 post 335

US to Euro spec headlights: pg17 post 337


Hope you find this thread to be helpful.

Good luck with your DIY project!

[Gillies]

Great thread !!