1968 2.0L Engine Tuning

[911Lguy]

I own a 1968 911L that was purchased about 7 years ago. I have been overhauling the various mechanical systems and exterior of the car with an eye towards keeping it in mostly stock condition. My main objective is to drive and enjoy the car on those sunny summer days here in the NW. With this objective in mind I have recently begun an “upper” engine rebuild to improve overall drivability. The technical knowledge imparted by the many contributors to multiple posts over the years has been invaluable (my thanks to our host).

On a couple of topics I am a little unsure how to proceed. Here’s the situation:

The car (VIN # 118.0.5255) was purchased on 3/20/68 from E. Islinger Motorfahrzeuge GmBH in Mannheim, factory equipped with US safety and emissions equipment, by a USAF servicewoman teaching in Germany. It was shipped to her home in California on 4/12/68 as she was transferred state-side (the car has a great early paperwork trail).

The engine and transmission #’s match the bill of sale, motor type 901/14 – 13179 (# 328.0.856), transmission type 902/1 (# 3281179). The emissions control system was completely removed at some point by POs, except for the vacuum retard system on the Bosch distributor (model # JFUDR6 / 0-231-169-01 aluminum body). The car has Weber 40 IDA 3C carburetors running with @ 3.0 – 3.5 psi fuel.

The engine has always run fairly well, except for hard starts and some backfiring upon deceleration. Here is how the engine was set up when the car was acquired:

1) POs removed the kettering ignition and replace it with a Permatune C911E coil-less unit.
2) new points, cap and rotor were installed. The points were set at 0.016”
3) Bosch W3DP0 platinum sparkplugs at 0.025” gap (I noticed during my current disassembly that they are heavily carbon fouled  carbs are running rich and / or weak ignition).
4) timing was set as follow, set at 30 +/- 2o BTDC at 6000 RPM, check for 2 – 5o ATDC @ 900 +/- 50 RPM, as prescribed in the owners manual and on the alternator strap sticker for 68 911Ls with US “smog devices”.
5) the fuel has been replaced regularly with premium gas, always stored with fuel stabilizer.

As I indicated my main desire is to enjoy the car with occasional summer drives, and minimal mechanical issues. Thus during my recent engine rebuild here is what I have done so far:

1) drained gas tank and replace all flexible fuel lines, replaced fuel pump and added large filter unit, added fuel pressure regulator and gauge, total rebuild of Webers with preliminary float level, idle mixture and air jet adjustments as per Weber manual.
2) Replaced Permatune unit with MSD 6AL ignition unit with blaster coil and tach adapter. Magnacore 8.5mm wires.

Here are my questions:
- since the emissions controls have all been removed should I retain the timing setting at 30 +/- 2o BTDC at 6000 RPM, with check at 2 – 5o ATDC @ 900 +/- 50 RPM?
- should I retain the vacuum retard feature on the distributor, or remove the lines and cap at the manifolds?
- Should I switch to a hotter plug (W3DP0  W5DP0), or wait to see if the MSD ignition unit and carb rebuild rectifies the fouling plugs?
- should I stay with the points or change to a Pertronix ignitor system? If Pertronix which unit fits the 0-231-169-01 distributor?
- should I stay with the rev-limiting rotor, or switch to a standard one since the MSD controls this function? If yes, what Bosch P/N do folks use?

I really appreciate the input. Once finished I will post some additional pictures detailing the final configuration. Happy motoring. Stewart.

[Rich Lambert]

Welcome! Nice looking car...the PNW needs more SWB's! We also need more pictures of your car.

I can answer 2 of your questions based on personal experience.

Ditch the points and go with a Pertronix.

Keep the rev limiter rotor as standard rotors have resistors that the MSD spark can melt. As far as I know, the rev limiting rotors don't have resistors...at least I haven't melted one yet.

Check out this thread about a meet up once a month at the XXX in Issaquah...coming up in 2 weeks.
http://forums.pelicanparts.com/pacific-northwest-us-wa-id-ut-hi-ak/267147-xxx-saturday-breakfasts-2nd-saturday-monthly.html

[Grady Clay]

Stewart,
Welcome to the Forum
You will find a lot of help here.

Strangely, I have a twin to your 911L.
It is a normal 911 USA coupe, burgundy/black.
I special ordered it new from Porsche KG in early 1968.
Mine is less than 100 newer than yours.
I suspect they were built within a day or few of each other.
Interestingly, my 901/14 is more than 300 newer.

The nose of my 911 has a bit more ‘road rash’ from following cars on track.
In fact, the stone chips exceed the original paint.

A useful mod I did (in late 1969) was to move the fuel pump to the front suspension cross member like a ’69 911E&S but with a ‘70T pump.

Later I added a return fuel line from the engine to the tank.
This permits a circulating fuel system to keep cool fuel at the carb inlets.

Another is to add the insulating spacers between the cylinder heads and the intake manifolds.
This helps prevent ‘heat soak’ from boiling the gas in the carburetor after you turn off the engine.

The boiling of the gas in the carbs is a major cause of hard starting from both gas fowling the sparkplugs and the float chambers being low or empty.

I tend to use NGK BP7ES.
I still have a Delta Mk10B from the late ‘60s.
If you keep the vacuum retard lubed, it works great.
Be sure the points-plate doesn’t become loose.
I agree, leave the rev-limit rotor in place.

What do you know about service of the engine & transmission?
There are two ‘time-bombs’.
One is the original hard rubber chain ramps.
As they got older and harder, they tend to brake and cause the cams to ‘jump timing’.
There are updated plastic ramps.

The other is the two stretch bolts that retain the transmission axle flanges.
The little locating ‘tits’ wear off and bad things happen.
Search Pelican on ”simplified differential”.
There is a permanent update but you can also simply replace the two bolts.

Keep it away from water and moisture.
It has been ‘rusting quietly’ since before it was assembled new.

There is a lot more to maintain your 911 as its current caretaker.
It appears well cared for.

Best,
Grady

[gsjohnson]

Nice looking car. I also have a matching numbers 68 911.
+1 on the NGK BP7ES Plugs. They are cheaper and bring the plug closer to the piston for better fire. The down side is that you replace them more often. I also pinched off my ignition retard, but I really couldn't tell the difference.

[911Lguy]

Thanks for the responses.

Rich ... let me get mobile and I'll come over to the East Side one Saturday. I am definately leaning towards the Pertronix. Seems like the rev-limiting rotor will stay!

Grady ... staying away from water in Seattle is quite challenging . Fortunately my garage doesn't leak! Did you buy the car in the US or pick it up in Germany?

I am in the process of updating the fuel pump and filter, when the install is finished I'll post a picture. I have attached a wiring diagram to show the electrical modifications (with acknowledgement to previous posts that have guided me).

I have been mulling the fuel return line. I am just now installing a fuel pump that is factory pre-set to 7 psi with a regulator to ensure the Webers only see 3 - 4 psi. Let me see how this works.

I have the intakes off the car at this point, tried to gently remove the studs but didn't want to force them while on the the engine ... I think this will wait until I do a full rebuild sometime in the future.

Definately will switch to the NGK BP7ES plugs ... with the MSD ignition I presume that I should start at about 0.040" and open in 0.005" increments until I find the best "zone".

The distributor just went to Ed Fall at Vintage Werks so that should ensure that all parts are moving smoothly and the curve is set properly. As GS suggested I try the vacuum line on, and off and plugged, to see whether drivability is improved.

About those time bombs. One of the POs installed the Carrera chain tensioner upgrade kit. Not sure when this was done (one of the POs has a picture of the car on the Pelican web site http://www.pelicanparts.com/911/911_photo_gallery/Kelly_68911L.jpg) as the natural history of the car from 1980 - 2000 is sketchy. Does this upgrade address the hard rubber chain ramps?

I'll do some homework on the transmission axle flange stretch bolts and get back if I have questions ... thanks for the heads up.

Regards. Stewart
_________________
68 911L (sweet)
81 F250 (american iron)
03 Jetta TDI (daily driver)
05 F350 (for the heavy lifting)

[911Lguy]

Thanks for the feedback.

Rich – When I get back on the road I’ll make my way over to the Eastside one Saturday. Sounds like the Pertronix is the way to go. Do you remember which P/N you used? Also, I will keep the rev-limiting rotor.

Grady – Did you buy your car in the US or Germany? Keeping your car away from water in Seattle is a little challenging , but the good news is the car is basically a “Sunday Driver” at this point.

The return line for the fuel pump sounds to be a great strategy to keep the fuel cool. However, I have already begun a fuel pump and filter replacement project so I will stay with that for now. Basically it’s a new fuel pump that is factory regulated to 7 psi with an external regulator to ensure the Webers only see 3 – 4 psi, along with a good fuel filter. I used previous Pelican posts to guide me on the wiring (see figure below), and will post a picture of the physical set up when finished.

I have the intake manifolds off the car at the moment, and tried to remove the studs but did not want to force them too much (they didn’t budge). I’ll defer the phenolytic spacer until I have the engine out and am overhauling the motor case.

As you and GS indicated I will switch to the NGK BP7ES plugs … starting at 0.040” and incrementing by 0.005” until I find the correct gap. Any other suggestions for starting gap?

The Bosch distributor was removed and sent to Ed Fall at Vintage Werks to ensure that the workings are in proper order and the curve calibrated correctly. I’ll try the vacuum retard feature on vs. off and plugged to see if any difference in performance is noted.

Between 1980 and 2000 there is not much maintenance history for the car (this is a pet peeve of mine). I do know that one of the POs installed the Carrera hydraulic chain tensioner system in 1999, would this address the hard rubber chain ramps?

I did some homework on the “simplified differential” posts you have participated in … that is definitely more excitement than I need! I saw some transmission work on the car back in 1994, but the shop’s notes were sketchy. My current plan to address this issue is to remove the driver side axel shaft, remove just one of the stretch bolts as you have described in a previous post. If the offending bolts are present, then I will remove the differential an upgrade following Randy Webb’s nice 2006 post. Should I remove the whole transmission or just pull the differential? Probably will just replace the axel shafts with new ones from our host (short $$).

Thanks again. I’ll post pictures once I’m back on the road from the Winter’s projects. Stewart.
__________________
1968 911L (sweet!)
1981 F250 (american iron)
2003 Jetta TDI (daily driver)
2005 F350 Diesel Dually (heavy hauler)

[Rich Lambert]

Stewart, this is the Pelican p/n for the Pertronix that I got..PEL-PT2862 (Pertronix Ignitor Electronic Ignition (2862), 911T/911E/911S (1969-71).

I have a '70 2.2 motor with an 008 distributor, so yours might be different.

[gsjohnson]

I think that 3 to 4 PSI fuel pressure is a little high for Webers. I run mine at 2.5 PSI. The Weber mod book that I have suggests this. I also run 48 IDAs on a 289 Ford with that same pressure. Anyone else have an opinion on the fuel pressure for Webers?

Grady-Thanks for the time bomb alert on the axle bolts. I was unaware of that one.

By the way, the serial # on my 67 built 68 911 is 11830186...Biege over red.

[Grady Clay]

Stewart,

Any slightly competent mechanic would install all six new chain ramps when installing Carrera tensioners.
So … I wouldn’t worry about the ramps.

I would try and collect the ’68-only mag chain covers.
You can always convert back to using ‘Turbo’ tensioners with the update chain sprocket support arm.

Yes, do the stretch bolts one side at a time.
Yes, you can do the update with the transmission in the car.
Just make sure everything stays clean.


I’m very much in favor of a circulating fuel system (like MFI, CIS, DME and other) in place of the ‘dead-end’ original system.
The purpose is to use the thermal mass of the fuel in the tank to keep cool fuel at the carb inlets.

Another is correcting Porsche’s poor choice of fuel pump location.
A pump located in the high temperature environment of the engine compartment and ’sucking’ fuel ‘up’ from the tank is less-than-ideal.

Porsche’s best solution was with the 1969 911E&S and ‘70T,E&S.
The ‘70T pump is applicable to our cars but using the circulation of the E&S.
For show, some circulate the fuel through a non-functioning Bendix or Hardi pump.

"
© Dr. Ing h.c. F. Porsche A.G.

Here is my adaptation:
"
© Dr. Ing. h.c. F. Porsche A.G.
Note the ‘tee’ just before and after the carbs.
The cool fuel flows past the carb float bowel inlets and most is returned to the tank.

I use a cylindrical aluminum CIS fuel filter and a Bosch fuel pump mounted on the front suspension cross member.

There should be an insulating sleeve on both the supply and return hoses from the end to the tunnel to the carbs.
The area around the transmission is where the heaters exhaust the very hot air when the heaters are off (hot weather).

Weber fuel recirculation- Questions
Braided Fuel Hose for a 72T MFI

This is a good opportunity to clean the fuel filter screen that is part of the outlet fitting (#3 above) at the fuel tank.
This is notoriously plugged with rust and debris.

I agree with the 2.5 psi AT the carb inlets.
Even then, you should confirm the float levels don’t ‘creep up’ idling for a long period (2 min).


BTW, never ‘warm up’ your 911 at idle.
Start, put in neutral with clutch out, put on seatbelt and drive briskly.
You should try to get it fully warm every time you drive.
Your 911 will like a good pull uphill to 6000 every time it is driven.
So will you.
(“But officer, it is part of my emissions control system.” )



Another issues with out 2.0 engines (and all through 2.7) is the smaller distributor cap compared to the 911SC.
This has greater risk of ‘cross-firing’ the ignition because the cap terminals are closer together.
There is also less volume of air inside the cap to disperse ionized air.
Both of these become more of an issue with very high energy, multi-firing ignition systems.
Wider spark plug gap exacerbates these problems but can fire a less-than-perfect mixture better.

I’m going to adapt the larger cap 911SC distributor to my 2.0 engine.
It is not a ‘bolt-in’ mod.



I have mixed feelings about Petronix.
It is a better solution than mechanical points but…
It is works or failed with no intermediate and it gives no indication of an impending malfunction.
I have continued with mechanical points and just keep them serviced.
When I convert to the magneto-electro-mechanical 911SC distributor, I’ll permanently fix the ‘green wire’ issue and have the best of both worlds.



While I have single phenolic insulating spacers on my 2.0 engine, I have them double on my three 2.6 race engines.
I recommend you use two per cylinder when you do the mod.
This requires even longer intake studs in the heads.

You can do this with the engine in the car.
Use a matched gasket to match the diameters of the gaskets and insulators.
Needless to say, do all the things possible to prevent braking a stud.
Patents, PB Blaster, heat and the right tools will make it work.
You can plug the intakes (I use rubber stoppers) if you must drill a broken stud.



There are serious rust issues with our cars.
Literally, they started to rust in the Factory before they were assembled.
There are many parts of the cars that are not painted.
They have been rusting quietly for 43+ years.
How fast depends on the environment.
I recommend a dehumidifier (or few) to keep the RH in your garage very low.

One of your next year ‘projects’ might be to disassemble and clean the rear suspension.
You will be amazed when you scrape all the rust out of the inside of the rear torsion bar tube.
There are quite a few other ‘rust prevention’ maintenance possible.



I special ordered my 911 through “Vern Hagestad Motor Co.”, our local VW-Porsche dealer at the time.
It was the longest wait of my life.

The ‘Importer’ was “Porsche Cars Southwest, Inc.”, an ‘agent’ for Porsche of America. The Porsche K.G. MSO was assigned to Porsche Cars Southwest and then to me.

Best,
Grady

[gsjohnson]

Where can you acquire the phenolic insulating spacers from?

[Grady Clay]

Originally Posted by gsjohnson

Where can you acquire the phenolic insulating spacers from?

I think this is the part from out host.
Pelican Parts - Product Information: PEL-PMO-HTIN-32
There isn’t an image or more info so I can’t be sure.

It is a PMO part.

Best,
Grady

[MrJTP]

The kit Grady mentions above contains the phenolic insulating spacers, gaskets and the longer studs you'll need when you put it all back together.

[911Lguy]

After a busy week, a little time in the shop with the P-car following up on the various suggestions. Here is where things stand (I’ll break the various points down in different responses for clarity)…

Transmission axle flange stretch bolt. I removed the drive shafts, removed the circle clip and cover plate, and removed only the stretch bolt on the driver’s side from the driveshaft flange. Good news is that the bolt did NOT have the “tit”, suggesting that one of the POs had this update performed. However, 3 additional issues have come up as a result of my investigations. Any wisdom offered would be welcomed.

First, I unbolted both ends of the drive shafts to get a look at the CV joints. As you can see in the first picture the transmission end looks OK, the grease was slightly stiff. I would simply clean and repack this.



However the outboard side looks quite different and the grease was very stiff.



The car has 80K miles, I have no idea if these are the original drive shafts. There were no gaskets present on either side of the drive shaft (there will be when I re-install them). The CV joints seem tight, but I would need to clean them and then re-assess to be sure. The axles are Lobro, rather than the Nadella, assuming the complete axle with CV joints made by Empi that our host retails is a good replacement for the originals then I would just buy new ones rather than clean and re-grease the old ones (especially since they would also need new boots too). Thoughts?

Second, while I was disassembling the rear drive components I decided to R&R the rear wheel bearings and inspect the seals and bearings (and other bits and pieces). The axle hub is definitely the early SWB system, the seals and bearing looked fine (they were re-packed in 1999 by a PO) so I will simple clean everything carefully, re-grease and install with a fresh “o”-ring. Although the inner shaft seal looks OK, typically I would replace such a seal. However, the PET parts catalog lists the P/N 901.331.283.00 as NLA. Any idea where to get a replacement? If not I can use the old one if necessary.

Third, was the really tough finding. As I drained the transmission fluid the magnetic plug had captured the following metal item.



To me this looks like the remnant of the spring from inside a sealing ring. Based on its size my guess was it came out of the seal on one of the driveshaft flanges. The transmission had a full seal replacement only 1100 miles back (done in a shop by the last owner, this included syncro ring replacements). The transmission works fine and does not leak fluid (Swepco). Any advice?

[911Lguy]

After reading many of the Tech Forum posts on the theory of how to best modify / update the fuel system in older 911s with Weber 40IDA3C carburetors, here is my approach. It will not score any concours points, but it should improve drivability / dependability and has a straightforward upgrade path.



For the moment I will simply deadhead the system with 2.5 psi pressure rather than having a return line. I agree that the recirculating system would keep the fuel delivered to the Webers cooler (by using the thermal mass of the fuel in the tank), but I will wait until the next time the engine / transmission are out to run a 2nd line thru the tunnel. The current system can be easily reconfigured to accommodate this. Other items to note …

- I removed the “fines” screen on the fuel tank inlet but retained the “coarse” brass screen. I want to keep the large pieces of tank debris from entering the system, but don’t want too much resistance on the suction side of the pump. Drained the tank … it looked good.

- All rubber lines were replaced with -6AN braided stainless and double hose clamped.

- I kept the fuel filter and pump in the engine compartment. While this is a hotter location than the forward crossmember, it makes for an easier filter change and pump / check valve service. Plus, a “hot” summer day here in Seattle is 75o … OK maybe it gets to 85 every now and then!

- I insulated the hard line as it comes out of the tunnel until it enters the fuel filter (the part near the heat exchangers) with Thermo Sleeve (ThermoTec 14005). Great suggestion.

- Many years of my mis-spent youth were in the marine industry. We always placed the filter before the pump to prevent debris from the tank from entering the pump, carbs, etc. Also, I really feel that 6 barrels pulling fuel from a 2.5 psi system needs unobstructed flow, thus a large surface area 10 um paper filter unit.

- Totally agree on the phenolytic spacers under the Webers to minimize heat transfer and fuel vaporization in the float chamber. As per your advise I coaxed the old studs out with a little PB blaster and the electric heat gun, and ordered the kit from our host.

Next I will re-assemble the whole system (with my freshly re-built Webers), check the float level and other adjustments as per the protocol from PMO (after an ignition system check) and we’ll see where we stand.

I will definitely utilize Grady’s engine warm-up and driving advice!

Thanks. Stewart.
_________________
68 911L (sweet)
81 F250 (american iron)
03 Jetta TDI (daily driver)
05 F350 Diesel Dually (heavy hauler)

[Grady Clay]

Stewart,

The ’66-’68 Lobro CV joints don’t use a gasket.
Attach the CV joint to the flanges clean and dry.

It is a challenge to install while not getting grease everywhere.
Use the old CV joint bolts as guide pins.
Take three bolts and cut off the heads.
Taper the cut-off end slightly (to ~4 mm) for the 1st cm or so.
Saw a screwdriver slot in the taper end.

Screw the (‘of local manufacture’) pins into the flanges (~3 turns) alternating holes.
Ease the freshly greased CV joint onto the pins.
If any grease gets on the contact surfaces, use Q-tips with solvent to clean.
(The space is only 1-2 cm so be careful.)
Use another three of the used bolts to tighten the CV joint to the flange.
Use a screwdriver and a magnet to unscrew and retrieve your pins.
Install another three used bolts and torque to spec.
Clean and inspect everything.

Remove two adjacent bolts and install the ‘moon plate’ washer, two new Schnorr washers and new 6-point Allen
head M8 bolts (MUST be ISO grade 12.9 or the older DIN 12K).
Install them clean and dry.
Use a new or freshly dressed 6 mm Allen socket.
Install the outboard joint to the stub axle flange vertically in a vice (protecting the pieces from the vice jaws).
Attaching to the transmission, use a very long extension so you can support the outboard end on the brake caliper.
This a lot of torque for this small (6 mm) wrench, keeping the wrench parallel and forced into the fastener is important.

Use a recently calibrated torque wrench.
Spec torque is: 4.3 mkp = 42.4 Nm = 31.1 ft-lbs.

Critically important is to re-torque after about 100 miles of driving.
Periodically thereafter.
I put these in the same category as head nuts and rocker arm shaft bolts.



Second
GOOD!
Your transmission has the ‘regular’ (non-simplified) differential.
This does not use the ‘tit’ on the end of the stretch bolt.

The ‘simplified’ differential was a cost-cutting feature.
The ‘regular’ differential has many more (and expensive to produce) parts.

I would simply clean and re-grease your existing CV joints.
Replace the boots.
Only if inspection shows a failure or exceedingly worn parts would I replace them.
With a 2.0 engine and good maintenance, these are multi-100K mi parts.




The rear wheel bearings are very robust and long lived.
Most failures I have seen have been from improper (and usually unnecessary) servicing.
Clean, reassemble with new lube and seals and they will survive ‘forever’.

For NLA, go to a company that sells seals.
The seals are:
900.113.011.50, B 42x55x7 DIN 6504.
999.113.085.40, DG 52x68x8/10/1.
The metric size numbers are on the seals.
The O-ring is:
999.701.091.50. Take the existing one to match.
Most industrial seal suppliers can supply these.



Third
The pieces you found in the transmission are from the axle flange seal.
Compare the spring pieces to a new seal to see if you have recovered all the pieces.

This would be a good time to replace both of the axle flange seals.
Inspect the old seals for a missing spring.
It may be from a prior seal removal.

When you ‘do’ your engine, a maintenance ‘look-see’ in the transmission may be warranted.




Your fuel system should be just fine.
If you intend to mount a front pump and filter someday, it may be useful to find a used front suspension cross member to modify.
While some of the ’68 front suspension is unique, the steel cross member is common ’68-’73.
The cast aluminum ’74-> version is compatible and allows more room for pump, filter and plumbing.
The aluminum version isn’t as strong and won’t appear original.

The modifications are to weld on several mounting tabs for the later pump mount and a mount for a filter.
This is easier than finding the ’69 911E&S and ’70 911T,E&S bolt-on brackets used.

...to run a 2nd line thru the tunnel.

I have never seen this done unless the floor pan is off for rust repair.
Mine is alongside the passenger side of the tunnel and protected with heat-shrink.
There must be NO fittings inside the cockpit.

Best,
Grady

Stewart, it seems we have a similar ‘fleet’:
68 911 (43 years sweet)
(a few more)
85 Camry (daily driver, GT3CUP plates)
86 Land Cruiser (90K mi recent replacement for SO)
78 E350 (American iron tow truck)
04 F350 Diesel Dually crew-cab (son’s heavy hauler)

[911Lguy]

Grady –

Thanks for the guidance on the axle / CV joint re-install. My wife will appreciate the suggestion of simply re-lubricating the CV joints rather than buying new ones (assuming they are tight after a complete cleaning). I particularly like the alignment “tool” suggestion. I’ll be careful not to get grease on the CV joint / flange mating surfaces; the last person in got grease all over the bolt threads, so I’ll be sure to completely clean the threads in flanges with a Q-tip. Rodger that on the gaskets. What do you think about the use of the Stage 8 fasteners? Ideola's Garage: Stage8 Fasteners for Porsches

I anticipated that the axle flange seal was responsible for the debris recovered from the transmission … the recovered material looks to be all the pieces (our host delivered the new seals on Sat). I will definitely proceed with replacing both of the axle flange seals.

The rear wheel bearings are in great shape. So just a clean, surface lube and reassemble is in order. Thanks for the heads up on the seals.

Along side the floor pan (with no fittings and heat-shrink) would be much easier for the fuel return line. That will be next winter.

Only a re-build of the Bosch 35A alternator is left and my “upper engine” rebuild project should be done in time for spring. Perhaps a lower engine rebuild and full check of the transmission will be “round two”. Your experience and suggestions on these projects has been most helpful, thank you. I’ll post pictures when it all comes together.

Kind Regards. Stewart.

[Grady Clay]

Stewart,

Here is a thread about CV joints.
While long, it is worth studying.

Reconstructing Constant Velocity (CV) Joints

This thread is most appropriate for those with 911S / 911SC with 100 mm CV joints but there is a lot relevant to our ‘68s and more.

The new ISO grade 12.9 6-piont bolts are more than suitable with new Schnorr ‘Safety Washers’ and re-torque.
I had a 2.5, a 2.8S and others in my car for many years.

Some recommend safety wire but I think that is only suitable after a few re-torque.
The wire must be removed to re-torque the bolts.
I like the ability to check occasionally without making it an all-day-project.
I have never found one of mine turning before torque spec.


For reference:
The ‘regular’ (‘non-simplified’) differential has an aluminum ‘plug’ in the center of the transmission axle flange.









With the ‘simplified’ version, you can see the head of the stretch bolt when the CV joint is removed.
No aluminum plug.



Here is the stretch bolt with ‘tit’ for the simplified version.



Note the wear (red arrow).
If (when) the tits wear and brake off - bad things happen.

Best,
Grady

[MrJTP]

A lot of good information in this thread. Thanks Grady!

[911Lguy]

Grady and Other Contributors –

After reading the CV joint posts, and a little time in the shop, I now have 2 freshly cleaned and re-greased Lobro axles / CV joints ready for re-installation. I have obtained fresh ISO 12.9 hex bolts, Schnorr washers and a new 6 mm hex bolt drive for the re-installation, and will be sure to re-torque to 31 – 32 ft. lbs. at install and after 100 miles or so.

Next I will clean and re-packed the rear wheel bearings with fresh lithium-based wheel bearing grease, then install the axles. As I mentioned this car has the Lobro axle and CV joints (and ‘regular’ differential in the transmission as detailed above) but the rear bearing assembly is definitely configured as shown for the Nardella axles in the PET diagram. Here’s is where the 95:5 rule has come into play. Most replacment axle parts were fairly easy to source, but the rear axle sealing ring (PET P/N 901-331-283-00, #16 in the diagram) is NLA from Porsche, Pelican and the other usual suspects. In addition, I have not found a local seal supplier whom can source this item despite several enquiries. Any suggestions?

Here are the critical dimensions for the seal:
OD = 37 mm
ID = 30 mm
Thickness = 3.5 - 4 mm
Height = 7 mm
The edges appear to have a 1 – 2 mm radius. I am assuming the material is Buna-N rubber. In the picture below, you can see that the seal on the left was mostly OK, but the seal on the right came out in pieces so they need replacment.



The upper end of the engine came back together nicely. PMO intake manifold heat spacers, freshly re-built Webers, PMO fuel bars, SS fuel lines, 10 micron canister style fuel filter, new fuel pump and relay, completely rebuilt pedal cluster and linkages, MSD ignition module, distributor rebuild, new coil, rebuilt alternator, fresh sparkplugs and some freshly powder coated metal. In the future I will tee off the SS fuel line at the rear of the car (running between the rear of the Webers) and run a return line to the fuel tank. I can then just relocate the fuel pressure regulator to the return side to create the ‘looping system’ you described instead of the current ‘dead head’ system.



Looking forward to final tuning and testing Grady’s engine warm-up procedures.

Thanks. Stewart.

[Walter_Middie]

Stewart,

Great looking car - can't wait until you post that it is running. But before you fire it up, do a search on Fram oil filters and "cool collars". The cool collar at least won't hurt anything, but the Fram oil filter may destroy your brand new engine. Once you fix those 2 items, you'll be ready to go.