71 911 T Drivetrain Rebuild
 

Hi guys,

My name is Nigel Aston Samuel and reside in Auckland, New Zealand. I'm quite fascinated by cars and mechanics but I'm no car mechanic/guru. I enjoy getting my hands dirty and generally working on my cars.

I'm new here however I've been reading these forums for quite a while now which has been extremely informative and enjoyable. I wasn't quite sure which way I wanted to go with my rebuild so have been thinking and throwing ideas about for about 6 months now and I think I finally have 30-50% of a plan but most importantly I know what my end goal needs to be.

http://images.tapatalk-cdn.com/16/01...f7f968a64c.jpg http://images.tapatalk-cdn.com/16/01...aea2e3f6d9.jpg http://images.tapatalk-cdn.com/16/01...e0fc8ed13b.jpg

Around March of last year I purchased the above car. A 1971 911 T which is my first 911 and Porsche. I wasn't sure which to go for, and had a drive in a 964 C2 and an 88 3.2, both LHD and both manual. I preferred a RHD due to the norm but as they are rare cars without a lot of choice I was happy to compromise. These didnt work out and later I found the 71. I think I would like to own a 3.2 G50 one day.

I had a few of the local car guys advise me on the car and I soon drove home with her. I knew the owner and the cars history since 2008 and always secretly thought about owning it ever since so it was quite apt when I purchased it 7 years later. The car came into NZ in 1996 and had a RHD conversion, which I think was a requirement at the time, however the job was done well and I didn't hold it against the car as I preferred that. I think it's safer to have a RHD in NZ. The car is originally from the USA, and I think it's a California car as I can't find any major rust on her, and all the panel gaps are perfect. Yay! The car had been repainted from its original metallic gold colour and had the interior/exterior updated. It still has the matching numbers motor and gearbox.

In 2009-2010 it had the engine rebuilt and since then has travelled 2000-3000 miles to when I purchased it last year March. Soon after I purchased it there was an issue and the engine has low compression on a cylinder. I think I was driving it too much and the cylinders needed retorqueing but I was unaware. Pretty soon there was a bang it rolled to a stop. The local car Mechanic said it wasn't the valves and mentioned it's coming through the case. Ever since I have been planning and thinking about what I want to do.

After Rennsport I thought about building a correct 71 ST or RSR but after thinking about it long and hard and talking to a few guys who are far more knowledgeable than me in the 911 circle I have decided to build a narrow body car with a huge grin factor which won't hurt the originality of the car that could be taken back to stock in the future.

So the end goal is a reliable street car with a bit more ponies than stock. Keep the character of the car period correct. An R Gruppe visual appearance.

So what does this mean for my engine rebuild,
1. Keep the matching numbers case and T crank
2. Oil Squirters
3. Shuffle Pin
4. 3.2 oil pump
5. Carrera chain tensioners
6. Bosch S Distributor with pertronics
7. 2.2s Pistons and Cylinders
8. Not sure whether to use the standard heads or open up to S Specs. Any advice on this would be great.
9. Solex or Mod Solex Cams
10. Gearbox rebuild
11. Possibly a few Wevo goodies to make the shifting more precise.
12. Maybe an LSD but need to do more reading on this. Any advice on this?

I think the above will be plenty of fun factor for me and is in keeping with the period of the car bar the items which add to the reliability/safety.

Over the last 6 months I've been reading Wayne's books on engine rebuilding and 101 projects which have been extremely interesting.

Currently the car sits on jack stands waiting the for engine to drop.
http://images.tapatalk-cdn.com/16/01...bd932abb1d.jpg

I'll keep updating this thread and look forward to any advice and help along the way as I'm very new to this so need all the help I can get!

Cheers,
Nigel


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Welcome.

1971 was the first year for oil squirters. Maybe it was only on the S but I thought your car should have them.

There's a recent thread on shuffle pinning. You need them to be a press fit for them to work as intended. That said, I don't think you'll need them.

Thanks for that Flieger, Glad you don't think I need shuffle pinning. I was planning on doing it as I would like to build it as reliable as i practically can. When do you think it's required? Motors over 2.2?


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I'll let someone better informed reply to that, but I'd say any motor reasonably close to stock in terms of output and rpm doesn't need it. I've not really seen any cases reported here of a race engine failing because it wasn't shuffle-pinned, though. Seems to be just engine builder preference or belt and suspenders. But I'm not an engine builder like Steve at Rennsport Systems.

Fair enough, it would be good to know the limits of shuffle pinning. We're any cases pinned from factory?


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It seems the 917 and RSR had bolts acting as shuffle pins, but with flats to allow the oil to still flow.

http://forums.pelicanparts.com/911-engine-rebuilding-forum/857332-case-shuffle.html

Interesting read. Thanks mate.


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Managed to sneak into the garage after dinner and removed

Rear sway bar
Electrical connections
And one drive shaft.

Just the other drive shaft and speedo cable to go. Didn't have a 27mm spanner for the speedo. Then I can attempt dropping the motor and gearbox.

Can i just disconnect the drive shafts from the gearbox or should I remove them completely?


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Nigel, welcome! Unless you are going to do some additional work on the suspension or wheel bearings, you can just remove them from the transmission. However, tie the up to prevent an excessive angle from putting undue pressure on the boots and CV joints.

In response to your initial question, your build is similar to mine on a '71 911T. I don't have it back together yet, so I can't comment on the effectiveness of the mods. As stated above, squirters were introduced in the '71 model year. However, my '71 built in Sept of '70 did not have them. I went with the Solex cam, based on the recommendation of the builder, and a dyno graph that showed a high, flat torque curve for a very similar motor. I had my distributor rebuilt by Kurt at ************-excellent service.

You should also consider modifying or replacing your carbs. Some people will say that the Zeniths work with bigger venturies and new jets, others say you should swap them out for Webers.

Good luck with the build!

dho

Thanks mate. I have Webers on mine so I'm lucky there. I have a Marelli distributor so will ask Kurt if they can rebuild it. Thanks for the comments on the shafts/cvs.


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Engine down today. Next step is to buy an engine stand. https://uploads.tapatalk-cdn.com/201...76fa614c95.jpg


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I'm in the middle of a build like yours. I can tell you what the machine shop suggested to me for my magnesium case and I think it's pretty much the baseline for what must be done:

Case halves decked and align bored
Spigots decked
Head and select mains web studs time-serted
Oil bypass mod
Squirters installed or if installed, tested (my 72 had them)
Case cleaned/hot dipped

I went with a "4 rib" magnesium oil pump (76-77.5) to go with the oil bypass mod. I don't know if there is an issue with aluminum pumps bolted inside mag cases but I do know that the 4 rib mag pump has the same specs as the Carrera pump (according to Bruce Anderson in his Performance Handbook) and you don't have to change your sump plate.

Good luck and post lots of pictures!

Thanks mate. I didn't know about that pump but it does sound like a great alternative.


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71t
 

Nigel, I was in your situation with worn out 71 T in 1980. I sent the case to California for boring for 90 mm p/c. bought 40 webers, and got a used L/E cam. new ssi. All this gave me about 170 hp (on a track it would accelerate with the 3.2 Carrera. This worked well for 30 years of track and street. I did need to add a front oil cooler for track use. Now that you can get 9.5 JE pistons you would have better performance than mine. Amazing what 40 or 50 extra hp does to the long hood experience. Since I money shifted on track I have used the L/E cams, webers,ssi on built 2.7 for additional 30 hp. IMHO 200 or so is enough hp. best Henry

Wow, that sounds very reliable! I would be extremely happy if I get 30 years out of my build [emoji16]. Thanks for your comments but I think I would prefer to stick with the 2.2 capacity due to the rarity, character and originality of the car in this instance. You are correct tho, a set of JEs would be sensational on a track with the 2.7s however my driving is far from glory. I just think in really quick. Which is why I'm pretty happy with a mildly hot rodded 2.2. I think 200bhp would be too much power for me. I'm not sure what power I will get but I hope torque is as flat as possible.


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2.2 vs 2.7
 

Nigel:

My first 911 was 70 T with Webers. It had great throttle response, but was not "fast".

I later owned a '72 E w/ the stock MFI that I then rebuilt to RS+ specs with 9.3:1 JE pistons, S cams and the RS MFI--the whole 9 yards.

While the E was definitely quicker than the T (a 2.4 vs a 2.2), the 2.7 RS was even a more quantum leap. Ran like a scalded cat right up to the 7300 red-line.

You mention torque--there's no substitute for displacement there, and the 2.7 has it all over a 2.2. Almost no comparison. While my T would lug below 3000 in higher gears--everyone "rows" them to keep them in the power band, the 2.7 had a much flatter torque curve and would pull away easily even in 5th gear at 2000 RPM.

I now have a stock 3.2 that I plan to upgrade to a 3.4 twin-plug with upgraded cams to push the power up in the rev band. The stock cam is very similar to the T grind--good low end power, but runs out of breath by 6000 RPM. It has even more torque than the 2.7, but, with the stock cam, is not as exciting when you rev it.

I would suggest you look into a 2.7 with E or S cams and carbs. With 9.3:1 JE pistons you can run on pump gas (93 octane here) no problem. Very reliable.

Good luck,
John

I keep hearing that only the newer 7R magnesium cases (roughly starting in later 73) are acceptable candidates for conversion to 90mm spigots. Converting older, lower designation case results in the spigots being unacceptably thin, running a higher risk of cracks and leaks. It's clear from the posts above that it can be done but I'd keep that in mind.

Original P/C's are 80mm. You could, without modification, go to 86mm. With the 66mm crank, that gives you a 2.3L. Again, without mod you could move to a 70.4 crank w/ correct rods and 86mm P/C's. You'd then have a 2.5 (2.45). Shooting for roughly 9:1 c/r with the piston selection, a Mod Solex cam and property tuned carbs, that would give you your smile factor for sure while maintaining a totally predictable power curve. I'd talk to someone like Camgrinder about the torque curve you really want. It may be that a T cam with the larger displacement is your ticket. Let me throw out that none of this is cheap. You may get better bang for your buck with a 3.0 or 3.2 and mothballing the 2.2. Just a thought...

There are a bunch of threads and discussions here about your options. You certainly aren't blazing a new trail here. Here are a few threads where some of the gurus chime in on builds like yours. Just search the engine rebuilding thread.

2.2 to 2.4 or 2.5, Way to go discussion.
2.2 rebuild
Case Designations
Mag cases
2.2 to 2.x
2.4 upgrade to 2.5

Thanks for the tips guys. I think I'm just way too simple when reading these comments above compared to my basic build. [emoji23]

I'm pretty keen to keep it at 2.2 due to the originality and character of the 70/71 year but pep it up a bit with a few period correct mods.

I guess it's not the torque monster or the biggest grin factor for he majority but it will be plenty for me.

Thanks for the posts above, I'll have a read of them. I've read a few of those but I don't mind reading them again.

Progress on the car,
So I've split the gearbox and case and removed the cluth/flywheel. Currently I need to modify my engine stand to bolt to the 911 motor. Thinking about buying a 911 yoke from eBay at around the $100 mark for the 5 member weldment. Once this is sorted I can begin the tear down. I'm pretty keen to spend more time but with work and an 18month old it's pretty tough going.


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Hi all,

I've been talking too much and not posting enough pictures so here's a few.
http://uploads.tapatalk-cdn.com/2016...c0864f2b61.jpg
http://uploads.tapatalk-cdn.com/2016...2d737da98f.jpg
http://uploads.tapatalk-cdn.com/2016...df9b64ff84.jpg
http://uploads.tapatalk-cdn.com/2016...423bbd9d8b.jpg
http://uploads.tapatalk-cdn.com/2016...6d18e8e1e7.jpg
http://uploads.tapatalk-cdn.com/2016...f04b513dac.jpg

Can you spot which cylinder is low on compression? Any thoughts on what the culprit is?


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Trim the cylinder tin back 1 inch out near the heads for better cooling and air flow.
Blow by on #1 or 6 from loose heads.
Looks really clean.
Bruce