911 tuning issues ('71 911T)

First off - this is a great forum and the tech articles are fantastic.
I have owned my '71 911T for 4mo. and absolutely love the car - only 69K miles, all origional and drives like a new car. However, there are some things that I cannot figure out how to solve - greatly appreciate any advice. After tuning it up (new points, rotor, and plugs, timed to TDC at idle, dwell is correct.

1) I ditched the Marelli distributor and replaced with a Bosch for a 911S (all the mechanic had). Is the advance the only difference and will this matter?
2) White smoke at start up. I have heard this is common with horizontal pistons but the cloud is pretty large, fills the garage if the wind is right!
3) Popping and muffled backfiring at warm-up and deceleration. Zenith 40TIN carbs, cleaned the float bowls and sprayed out with carb cleaner - still acting up. Could valve adjustment be an issue? Are Webbers a better refit?
4) Transmission is sloppy into 2nd and of course first is nearly impossible unless you are moving. Is there a linkage adjustment that will help or is this just worn sychros?
Thanks for any help.

Hi there,
I own a '70 911T. I also replaced the Marelli distributor with a Bosch unit for the T model of the same year, from Pelican itself. It works great. I also suffer the exact same symptoms about backfiring under mid-range mild acceleration and full deceleration. I refurbished the Zenith carburators but to no avail so far. Is the mixture too lean ???
For the gearbox:
My car has a lot of mileage on that gear box and first & reverse were noisy when cold and almost impossible to engage when warm.
I thought the clutch might be shot but an old mechanic told me something would go wrong well before I would need to replace that clutch. He adjusted the cable and it was great. Not smooth as in a new car but very workable. Only when the car is very hot then reverse becomes slightly noisy. Everytime these two gears give me trouble, I go under the car and turn the adjuster a 1/4 turn and basta for a good 2000 miles....
As for 2d gear which I'm sure has been abused by all the previous owners going too fast with the gear lever, I found that installing the spring kit sold by Automotion for the gear lever and taking my time going from 1st to 2d has made great progress : I will now even downshift fast from 3rd to 2d without squeazing my teeth in fear as I used to do.
Well, hope it could help and keep me posted for the backfiring problem!!
For the gearbox, I imagined the worst on the inside but the adjustment of the clutch did it...
Good Luck.
Thierry
PS: Try to remenber to engage 1st gear before the car gets to a complete stop ( stop sign, red light etc... ) I do it within the last feet before stoping and it is smooth as silk then.

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