1968 Porsche 912 Restoration
Pulling the engine, having it rebuilt, re-install
I purchased my 912 in Sacramento in 1982, and the car had Oregon plates on it. This year (summer, 2002), it really needed some restoration work and the engine was running very poorly. So I mapped out a plan to rebuild the engine, and restore the carpets, seats, brakes, and rust prevention on interior sheet metal. The 1968 912 engine has only 1580 cc of displacement, so it is not that powerful. To increase engine horsepower, I combined:
- 86mm big bore kit (1750 cc)
- Tricom 105 cam
- Weber 44IDF carb kit
- Sebring tuned exhaust
- Pertronix breakerless electronic ignition
- Jacobs Omni Magnum ignition enhancement system (which increases spark energy)
- New cam followers (lifters)
- New valve springs, and retainers, etc.
Here is my 1968 912 before work commenced.
For a comprehensive restoration job in which you plan on rebuilding the engine, treating rust, doing brakes, etc, it is best to use four jack stands, using smaller ones in the front and larger heavy duty ones in the rear. The smaller jack stands should be placed underneath a wooden 2x4 beneath the frame behind the front wheels. The wooden block will prevent damage to the frame. If the block of wood is not used, the jack stand would probably punch through the metal in this area.
The larger rear jack stands should be positioned below the torsion bar housing. The torsion bar housing frame holds the weight of the car, transmission, plus the engine -- it is pretty strong.
Now the car is totally jacked up for pulling the engine and transmission.
I removed all of the wheels, since I wanted to rebuild the brake calipers and have the rotors turned. Furthermore, with the wheels removed, you can get in and out below the car more easily, which is essential for pulling the transmission and engine.
To make room for the engine as it is being pulled out from the back of the car, you should remove the rear bumbers and sheet metal (that the license plate bolts to). If you don't do this, you probably won't be able to get the engine out of the back of the car since the top of the fan shroud will not clear the sheet metal.
In order to pull the engine with the transmission attached, I first unfastened the shift coupler which is accessible on the floor of car in front of the rear seats (center). Without removing the shift coupler, you can't pull the transmission. Second, and later, I removed the battery, unbolted the copper electrical ground which is in front of the transmission, removed the starter wires, clutch cable, and throttle linkage. In the engine bay I removed the generator leads, positive and negative leads that attach to the ignition coil, and wires that attach to sending units for oil temperature and pressure.
Here it is, a sick, underpowered, poorly running 1580 cc 912 engine.
Once the engine and transmission were out, there was more room to look around in the engine bay to inspect some of the sheet metal and rubber trim. Actually, in reading a lot of stories about overheating, you can't have any damage to the rubber seal around the bottom of the engine bay. If you do, there may an air gap between the sheet metal and rubber that will let hot exhaust and cooling air thrown out the bottom of the heater boxes back up into the engine bay. Only cool air is supposed to enter the engine bay.
During the engine rebuild, I took the rear seats down to sheet metal to inspect for rust, and indeed found some that originated with water that leaked from the back window rubber. It takes about 8 years for rubber surrounding a rear window to start leaking water. Once it does, the water travels down the inside of the car beneath the upholstery where it sets in and begins to rust.
More rust in the back seat area.
Bottom of rear seats actually rusted through.
I pulled the front carpets, and removed rust on the floor pans as well. A good circular wire brush and an electric drill worked fine.
There was plenty of rust, even surrounding the rear axles and drum brakes (emergency brakes).
POR-15 anti-rust kit applied to rear sheet metal behind quarter-window, available from
POR-15 applied to rear seat sheet metal.
POR-15 after first coat on floor pan.
Be sure to use several types of gloves when working with POR-15 products. Also, you really need to use Marine Clean (or some other detergent) and Metal Ready to prepare the metal before applying POR-15. I tried applying POR-15 to some metal without cleaning it with Marine Clean and the POR-15 did not tightly bond in some spots. Metal Ready has zinc in it which helps trick the ferrous oxidation reaction so that rust is terminated. Zinc-containing phosphoric acids used for anti-rust are the best!
I also fiberglassed the rear seat sheet metal after POR-15 was applied. Acetone is the solvent for fiberglass epoxy. For this brand (Bondo, Atlanta, GA), be sure to use a minimum of 8 drops of hardener for each ounce of epoxy, or the mixture won't "catalyze" and will remain soft and gooey.
Some of the parts I ordered are as follows. Here are the "upper" and "lower" gasket kits (from Performance Products - 15% off sale).
Here is the Tricom 105 camshaft (from Performance Products - 15% off sale). Along with the new cam, I ordered 8 cam followers (lifters)
8 valve guides (from Performance Products). I also purchased 8 new valve springs, retainers, and needed a new exhaust valve.
86mm big bore kit including pistons, cylinders, and connecting pins with retainers. This will provide 1750 cc (from Performance Products - 15% off sale)
Weber 44 kit (from Performance Products - 15% off sale)
Close up of a new Weber
Air filters that came with the Weber kit
Intake manifolds that came with the Weber kit
New door panels (from Parts Obsolete)
When I was tightening the 3/8" NPT (National pipe thread) oil cooler fitting in the "full-flow" timing cover, I overtorqued the fitting and broke off a piece of thread from the cover. I had no choice but to get this welded
A local shop welded the cast aluminum by building up the damaged area, and retapped the tapered 3/8" NPT hole
Because welding the cast aluminum could warp the timing cover, I checked for low areas on the gasket surface by gently sanding (with water) the timing cover on 320 wet and dry sanding paper glued (with 3M spray glue) to a piece of glass. Sure enough, it was warped to the extent that I needed some JB weld (liquid metal epoxy) applied to the low areas.
The next day, after the JB weld was dry, it took about an hour (and a glass of wine after a long day of other restoration activities) to get the timing cover fully surfaced.
Rebuilt 912 (wiring not yet bundled) with a 86mm pistons (1750 cc) big bore kit, Tricom 105 cam, new cam lifters, new valve guides, new valve springs, retainers, all of which were assembled during the engine rebuild. After I received the engine casing with heads after the rebuild, I installed a new clutch, new gland nut, new intake manifolds, sanded and painted sheet metal, Webers and filters, generator pulleys and nut, a Pertronix Ignitor breakerless ignition (points), a Jacobs Omni Magnum (yes, it starts in 1/2 crank), Sebring tuned exhaust, Mocal 19-row oil cooler, stainless steel braided oil cooler lines, aluminum hose fittings and hose ends (size: -10 AN), new plugs, wires. The wires still need to be bundled and hidden. I also ordered some velcro oil cooler line covers that reflect heat from the exhaust tubes.
After filling the engine with oil, connecting wires, putting gas in the fuel tank, priming the carbs with gas, and connecting the battery, I cranked the engine and it started right away. Timing was set at 3-degrees TDC for the number 1 cylinder. The combination of new pistons, cam, header, and carbs may have increased horse power to ~110-120. Overall, the engine runs terrific, with incredible throttle response and impressive low- and high-end torque.
There are a couple of caveats, however, for such engine modifications. First, the Jacobs Omni Magnum creates intense spark heat, and therefore I need to use the coolest spark plugs available. Second, the big bore kit raises the compression ratio to ~9:1, causing the combustion to literally get blown away from the spark. This can be compensated for by using premium gas with higher octane, which can ensure a more efficient and faster combustion. Lastly, the big bore kit also raises cylinder head temperature, so I need to keep the engine as cool as possible. The simplest way to do this is to ensure that the fan blades and fan housing are clean, and that the rubber between the sheet metal and the engine bay forms a tight seal, since warm air from the headers and heater boxes (blowing out hot air that flows downward over the heads) can rise vertically into the engine bay adding unnecessary heat.
By the way, I had to make new linkage for the Webers by threading some round mretal stock (steel), and screwing on the ball joints at the end of the new threaded rods. (I got the 4-right threaded carb linkage ball joints from Klasse 356 in Allentown, PA; see parts links below). Here, I show a close up of the right Weber and some 3/16" stock that I threaded (right-handed thread obviously) on both ends and bent almost at a right angle. The ball joint also has to be bolted into the back of the throttle arm.
Throttle linkage for right Weber. The left Weber also needs new linkage but it does not have to be angled near the throttle arm, and the ball joint should be bolted into the front of the throttle arm.
The die I used on the 3/16" stock metal for the throttle linkage was 5 mm x 0.80 pitch. Be sure to use some oil when threading.
I mounted the Jacobs Omni Magnum on the left firewall toward the rear from the voltage regulator.
Mocal oil cooler. I had to fabricate some flat iron on which I mounted the Mocal oil cooler. The sheet metal itself is screwed onto the engine mount crossbar, in which I tapped threads for the mounting bolts. The cooler itself is fastened with lock nuts onto the sheet metal, and sits about one inch from the sheet metal below.
The aluminum fittings are size "Army-Navy dash 10" (AN-10) with stainless steel braided hose (also AN-10), all made by Aeroquip, and available from Racer Parts Wholesale.
Here is another image of the sheet metal on which the Mocal oil cooler is mounted. The Mocal oil cooler removes a tremendous amount of heat from the oil coming out of the oil pump. After about 20 minutes of run-time, the aluminum fitting for oil input into the cooler feels (by touch) about four times as hot as the exit fitting containing the cooled oil. This is important because I use a bypass cover and don't have a stock oil cooler mounted on the casing under the fan shroud.
Another image showing how the Mocal oil cooler is mounted to the cross-member. The bottom of the Mocal cooler is about 1 inch above the surface of the sheet metal below and does not come in contact with anything but the mounting brackets I made.
Close up of the EMPI oil filter mount and oil thermostat into which the Aeroquip steel-braided oil cooler hose and Aeroquip "hose-end" fittings are connected. (see EMPI link at bottom of page).
Castrol Heavy Duty SAE-30 and synthetic transaxle gear oil. As far as engine oil is concerned, I am now using Castrol Heavy Duty SAE-30, which is a non-"W" straight weight oil. Previously, before the rebuild I used Castrol 20W-50. I like the straight weight oils because they have few if any polymers in them, which are used to expand and contract as the oil changes temperature. The problem with W oils is that a portion of the oil (what you want) is displaced by polymers (plastics), which don't provide lubrication and can burn up.
I will probably change to Mobil 1 synthetic oil at 5000 break-in miles. Synthetic oils significantly reduce engine friction, which results in heat. If I could offer a rule-of-thumb for beefed up 912 engines it would be: use the coolest plugs, premium gas, and synthetic oil.
The crankshaft gland nut needed replacement and had to be torqued about 225 foot-pounds. This required a "cheater-bar" that essentially doubled the length of the torque wrench.
Rebuilt brake calipers and turned rotors. I had to purchase new break lines because there were actually bubble on the surface of the old ones.
Brake cleaner fluid is probably the best degreaser and parts cleaner since it disolves most oils and grease, and dries very fast. I used it to clean bolts, gasket surfaces, and anything with dirt/grease/oil on it that needed to be exceptionally clean.
Fuel tank after treatment with POR-15's U.S. Standard Tank Coating. I still have to POR-15 the fuel tank compartment in the front of the car.
Interior is totally stripped down with POR-15 on floor pans, rear seat sheet metal, and back window frame.
Front floor pans, awaiting Dynamat, carpeting, and then new seats.
The grille of the rear deck lid was previously painted an ugly flat black, and I painted it high metallic silver along with the 912 logo
RustOleum "Metallic" used for for the rear deck grille.
(every Porsche owner should have one of these!. Amazingly, I was able to find a new 5 HP B&S for $262.)
Installing Dynamat Original
Placement of the vibration and and sound deadening material "Dynamat (Original)" in the back seat area and rear deck areas. I did a lot of research of which Dynamat to use, such as Dynaliner, Dynamat Super, etc. and it worked out that if you don't use Dynamat Original then it is not worth using anything else. Certainly, given what I learned about Dynamat, in a Porsche you really want to use Dynamat original to dampen vibrations eminating from the engine bay and transmission (which is essentially below the rear seats!), and to road noises from tire contact etc. My 912 was actually very loud inside to the extent that some riders asked me how I can stand the noise. Actually, there is nothing more pleasureful than the sound of a Porsche engine winding out as you go through the gears, especially when you step on the throttles quite heavily.
Although Dynamat comes with a self-adhesive backing, I still needed to use 3M #90 High-Strength spray glue since Dynamat's self-adhesive was inadequate for tight bonding. I first tried using 3M #77, but it did not firmly glue down the Dynamat.
The Dynamat original came in boxes that provided 13 square-foot, and I actually needed four boxes for a total of 52 square feet.
This shows some 1/8" sheet metal on which I used JB-weld to secure a seat belt bolt. These pieces of sheet metal will be bolted into the area where the threaded holes rusted out below both quarter-windows.
New carpet kit installed along with Cerullo GT seats.
Seat mounting bracket.
Seat mounting bracket.
New carpet below rear deck and surrounding rear seat area.
In January 2004, the full paint job was started. All bumbers, trim molding, doors, front hood, rear deck, etc. were taken off the car.
Since the car was taken down to metal during a paint job in Sacramento in 1981, I did not want to do it again. So we only went down to (and into) the primer, and/or metal as necessary. There was some sheet metal replaced in the fenders and new rockers were installed on both sides. Some extra work involved removing bumps and wrinkles in the entire car that were simply due to aging of the sheet metal. The final product is going to be awesome.
We were able to get a perfect match on the original factory paint color. Here, the doors less door panels, etc., are shown.
Doors less the handles and mirrors.
Paint with clear coat completed.
Color sanding of the complete car with 1500 grit paper started today (see lower left rear quarter). This will be followed with complete sanding using 2000 grit, and then buffing and polishing. The results will be tremendous.
Done. The date is June 11, 2004 and I just picked up the car from the restorer (painter). Before the following pictures were taken, I applied a coat of Mother's original California Gold wax, and it doubled the shine after buffing. The four coats of clear coat over several coats of the original Karmann color will last a lifetime.
There were numerous replacements made during the body restoration and painting: new rocker panels (right and left), sheet metal welded in where rust was, wrinkles taken out of all body panels, new headliner, new rubber seals everywhere, new exterior mirrors, new deco trim, new hood emblem, new cowl cover and screen, seat belt mountings next to rear seats refabricated, wheelwells cleaned and rustproofed, and the front trunk stripped and rustproofed.
Handbrakes, handbrake cables, rear shock absorbers, trailing (control) arms, rear hub removal (part 297)
In May 2006, I replaced the handbrakes, handbrake cables, and removed the trailing arms on boths sides to replace the rubber bushings where the arms bolt to the frame. Since the shocks had to be unfastened when the trailing arms were removed, they also were replaced.
There is no trick to removing the trailing arms. Here are the steps for removing the trailing arm on one side:
Overall, restoring the handbrakes and cables, trailing arms, and shocks took several weekends that were pretty much full-time all Saturday and Sunday.
- Place the rear of the car up on jack stands, with the jacks placed below the torsion bar housing (see above).
- Remove the wheel.
- Pull the disk (drum) off the hub (the hub is the piece with 5 studs in it).
- Remove the hydraulic brake line from the caliper (cover it with a cloth or ziploc bag) and remove the brake caliper.
- Remove the cotter pin and the castelated nut on the handbrake cable, and disassemble and remove the handbrakes.
- Remove the cotter pin from the axle nut, and then loosen the nut with a wrench and cheater bar (see above). Be careful here, since the service manual states that the torque applied to the wrench is sufficient to knock the car off the jack stands -- this would certainly ruin your day!
- Unbolt the transaxle at the transmission and wheel and remove it, pulling the axle out of the hub. Be careful with the axle, and place in it a clean location.
- Jack up the trailing arm about 3" and loosen the bolt for the shock absorber, and then unfasten the bolt at the top of the shock absorber inside the engine housing, and then remove the shock absorber. Release the tension on the jack and remove the jack. (I like to remove the shock absorber first so there is room to work with the next step.)
- Remove the hub (containing the 5 wheel studs). The service manual calls for Part 297 to hammer and knock the hub out by hitting part 297 from the inside against the hub. I used a Craftsman socket that fit the inside diameter of the axle perfectly against the hub. No damage was done the hub when done.
- Loosen the 4 bolts that hold the brake pad holder to the trailing arm, and remove.
- Unclip the brake line fastener clamp form the trailing arm.
- Next, remove the four bolts holding the trailing arm to the spring plate, and don't worry about tension on the spring plate, there isn't any tension on it.
- Remove the bolt that fastens the trailing arm to the frame.
- Carefully work the trailing arm out of the holding mount on the frame and the brake line.
- That's it.
- When working with both sides of the car, carefully store all parts in different boxes for the left and right side of the care. Don't mix up the axles, transaxle parts, hubs, brakes, etc.
- At this point I totally disassembled the transaxles.
- Grease on transaxle joints and bearings can be dissolved with a spray can of brake cleaner, and repacked using Molybdenum grease (not lithium grease). Moly grease is for high heat parts such as transaxles and wheel bearings.
- I also used an electric drill and a Dremel Moto tool with wire brush attachments to removed dirt and rust on both trailing arms, brake pad holders, and hubs.
- I then applied Marine Clean, Metal ready, and POR-15 anti-rust paint to the trailing arm.
- New new rubber boots and fasteners for the transaxles were also installed.
- Relined brake pads were installed along with new springs.
- New Koni shock absorbers were also installed.
Trailing arms, wheel hubs, drums, and axles showing new coat of POR-15, new CV joint boot kits, and Koni red shocks (for the rear). Symmetry kept intact: parts for driver side vs. parts on passenger side.
Same as above, but at another angle.
Well, it's March 2008, and the brake caliper rebuilds I had done several years ago were not too bad, except one caliper was totally rusted. The pistons in the calipers were not stainless steel, so they were prone to rust. The likelihood of this occurring can be drastically minimized by changing your brake fluid at least once a year -- no matter where you live -- in order to flush out water and moisture absorbed in the brake fluid.
Because of the rusted piston, I sent the calipers off to White Post Restorations in Virginia, and the total job cost about 1k. They bored out new piston seats, and custom-machined new brass sleeves and new stainless pistons. Turn-around was less than a week. Here are some pictures:
I am also now replacing the master cylinder(MC), since it's 40 years old. I already replaced all the brake lines recently, so it makes sense to swap out the MC now a new one.
Hoerr Racing Products: Velcro-based oil cooler line insulation
Racer Parts Wholesale: Stainless steel braided hose, Aeroquip aluminum fittings
British American Transfer: Mocal oil cooler
Performance Products: Big bore kit, Webers, Tricom 105 cam, cam lifters, valve guides, valve springs, Sebring tuned exhaust, Bursch J-pipes, Jacobs Omni Magnum, gland nut, gasket kit, clutch disk, clutch alignment tool, flywheel locking tool, Cerullo GT seats, carpet kit, sheet metal kit, shift kit, brake pads, brake caliper kits, Bosch "T" spark plugs (W6BC), ignition wires (Spark plug wires), oil seal,
Tweeks: Pertronix breakerless ignition, engine mount
Zims: Front wheel bearings, front and rear brake lines, Loctite 574, Thread Life antiseize compound, various gaskets
Klasse 356: Carburetor linkage ball joints
POR-15 Paint Over Rust: Marine Clean cleaner and degreaser, Metal Ready phosphoric acid with zinc, POR-15 paint, fuel tank liner kit
Dynamat: Sound and vibration dampening material used beneath carpet
Parts Obsolete: Door panels
Porsche Parts/Supplies/Racing Links
Restoration Design Porsche Parts
Hoerr Racing Products
Racer Parts Wholesale
Pelican Parts - DriveWerks Technical Articles
Gene Berg Tech Tips
Dave's Porsche 912