1971 - 911T Assorted Questions

[HOFF+2]

I have a few different questions that I need help with on my 1971 - 911T that is currently being restored.

1). I just received the COA on the vehicle and everything checks out except I do not understand the type wheels listed as 'Pressure Cast Wheels 5.5 J x 15'. The car currently has imitation Fuchs wheels on it but I've been told that the 'correct' wheels would be the Mahle gas burners? Another bit of feedback I got was that the 'cookie cutter' wheel would be correct. Is there a definite 'correct' wheel type?

2). The 40 TIN Zenith carbs have been re-built but as you increase the throttle lever by hand from idle to approx. 2000 rpm...there is 'poping' sound coming from the carbs. The CDI box is new as are the plugs, points, cap & rotor. The problem is worse when the engine is cold but above 2000 rpm it does not make the sound and runs well. I've tried adjusting the carbs per the article I found on the TIN's but cannot seem to get it resolved. The only thing I have not replaced are the wires. Any thoughts?

3). The car has 59,500 original miles on it and I decided to replace the valve cover gaskets. I bought what was sold as an OEM set but I cannot get them to stop leaking. I have torqued them with the correct pattern. Starting out at 12 inch lbs...then 18...still leaking and now up to about 22. I'm afraid to go any higher but the oil seems to be seaping down a couple of the lower bolts / washers. Are there better gasket sets (perhaps silicone) that will prevent this?

4). Lastly, I have replaced the wiper motor, both the relays and the stalk for the wipers and in the 'off' position, they 'dock' on the drivers side. In most of the pictures I've seen, they should be on the passenger side? Is this correct...if so...how this get corrected? All positions of the switch work fine.

Well...that it for now. Any and all imput is greatly appreciated!

[darrin]

i can help you with #4 -- wipers are designed to park on the driver's side -- this can be reversed if desired, but I like it that way, as the first and last "wipes" are from/to the drivers side, this more effectively clears my vision.

[Bob Ashlock]

Regarding #3, those '70/71 engines had magnesium valve covers and they warp very easily, both from over-tightening and from heat cycling. If in doubt, just find a very flat surface and lay them down on it ... you will likely be able to 'wobble' them if they are distorted. On one of my recent cars, I tried milling them back down to flat, but as soon as they were used a while, they started leaking again. The ultimate solution is to go with the later aluminum valve covers, available from our host I believe. I was lucky to have a friend provide a good used set to me, and the seepage was reduced to near-nothing. I also used the silicone rubber gaskets provided by our host with very good results. But be careful not to over-tighten the nuts as those gaskets are very soft and you can still distort even the aluminum covers if you get too ambitious.

[Daves911L]

You were told correctly . Pressure cast 5.5 x 15 wheels would indeed refer to the Mahle "gas burners". The Cookie cutter did not appear until late in calendar 1972 for 1973 m.y. cars

Popping from the carbs suggests a lean condition and could be one of many things. Low float level. Plugged idle jets. That goofy auxiliary circuit the Zeniths have, which I've forgotten how it all works but there is a microswitch/rpm transducer coming it to play around the rpm you mention. Or my personal favorite: plugged accelerator pump nozzles/check valves.

Pictures you have been looking at must all have been of very early cars. '65-'67 wipers park on the right. '68-on park to the left.

Take Bobs good advice and buy the later style ribbed valve covers.

[HOFF+2]

My personal thanks goes out to each of you for your responses! This site never ceases to amaze me with the vast knowledge base of it's members. Thank you again! Sincerely, HOFF+2

[Allen_70S]

Hoff+2:

I believe I have the answer regarding the 71 wheels. The standard factory installed wheels for the 71T were 5 1/2 x 15 silver painted steel wheels. Optional at the factory were (1) 5 1/2 x 15 chrome plated steel wheels, (2) the 10 spoke 5.5 x 15 Mahle cast magnesium (gasburner) wheels and (3) the 6 x 15 Fuchs which were standard on the “S”. B. Johnson's book “911 and 912 Restorers Guide to Authenticity” has pictures of these wheels. Also, per 911t.pca.org/options the steel wheels (painted or chromed) had a factory installed hubcap featuring an embossed/in relief Porsche crest at its center. A dealer (not factory) installed option for these wheels was a hubcap that had a multi-color enamel Porsche crest at its center. Search redux with my ID for some other detailed information about 70/71 standard and optional equipment.

Al

[thumbdoctor]

Are you using the factory air filter tin or pod filters with rain hats?. Seems to me the Zenith (and Webers) tend to pop a little when cold due to slight leaness using open element filters. Is the popping on the same cylinders or all of them intermittently.?

[ddubois]

Another wheel option for the 71T was the 14" Fuchs as part of the 'Comfort' package. This is what came on my 71T and are listed on the COA.
Use the silicone gaskets with the turbo valve covers. I've proved to myself they are reusable and will not leak as long as you follow the recommended low torque.
As for the Zeniths, you have a long road ahead. It's taken me hundreds of hours fiddling with everything in the system from the fuel pump to the jets to finally get it right. You mentioned not replacing the plug wires. I would replace those with something like Magnecors. I've also installed a MSD that, I feel, helps a lot with carb tuning.
My opinion on tuning Zeniths is that you need to get everything else in order before addressing carb adjustments. Timing, valve adjustment, points, ignition system from the CDI to the spark plugs, fuel pump pressure, float level (needs to be perfect), etc all have to be properly adjusted before you break out the synchrometer and start messing with the air bypass, idle speed and idle mixture adjustments. I have found my Innovate AFR meter to be very helpful when searching for the correct jets. Also purchase a jet gauge and don't believe what is stamped on the jet, they've likely been reamed larger.
Another advantage of using the stock air filter vs. rain hats is the ability to hook up the hot air delivery to the filter. I think that helps with the cold start warm up. Also make sure your throttle lever between the seats is working. You need it for cold starts. The plastic piece in the tunnel breaks and is a PITA to replace.
Search on my username and barn find or zenith for a history of the work on my 71T.

[HOFF+2]

Well...it sure seems that there are a few different options as to the 'correct' wheel for the 1971 - 911T. It's interesting that besided the fake (4) Fukes, the spare is a steel stamped wheel as the remaining spare. I'm just not sure is those wheels would have been considered at the 'pressure cast' wheels as referenced in the COA?

Regarding the carbs....the stock air cleaner is in place. I did notice for whatever reason that the 'micro switch' on the left bank is far lower than the actuating 'wheel' that it is meant to make contact with. Basically, the switch is never in range and as such, never depressed. I will look into why the switch is so low in it's mounting. Will also proceed with the new wires, silicone gasket set and hopefully the turbo aluminum valve covers (they are pretty priced especially for the set of 4)!

What does that micro swith actually do and can it be tested to see if it even works properly? Thanks again to all!

[Daves911L]

There were many different options available in '71. But your COA clearly identifies the "correct" wheel for your particular car as the Mahle "gas burner". Most likely a previous owner sold the 5 gas burners originally with your car, bought the fake fuchs, and scrounged the cheapest steel wheel he could find for a spare. Unfortunately the "gas burner" is now sort of a rare and expensive wheel. Much ballyhoo-ed as the lightest wheel you could get for your 911. They are also, in my opinion, rather ugly (I have owned two cars with them, and once bought a NOS set of 4 from a Porsche+Audi dealership closing out old inventory for $300). Here is a set currently for sale on the 356 Registry site:

Ads - 356 Parts/Accessories - Mahle Gas Burners

[ddubois]

Originally Posted by HOFF+2

What does that micro swith actually do and can it be tested to see if it even works properly? Thanks again to all!

Do a search on 'air enrichment' to learn how the complicated system of RPM transducers, switches, solenoid and diaphragm valves connected by a bunch of vacuum hoses works, then disconnect everything and plug all the vacuum ports. You don't need it.

[Allen_70S]

I agree with ddubois regarding the 5.5 x 14 Fuchs being an option on the '71 T. My initial answer was based on Johnson's book, while the 911t.pca site does show the 5.5 x 14 forged light alloy (Fuchs) to be a factory option. Just one of the many instances where the experts show conflicting information for the early cars. Johnson's book also shows that ALL 71T with the optional Boge (Standard on the E) self leveling hydropneumatic front struts (a small percentage of production) came with the 5.5 x 14 light alloy Fuchs. I assume that this is because the tire/wheel/strut was designed as a system.