71T - Bosch replacement for Marelli distributor

Quick question. Does anyone know if a bosch distributor from a 69T will work on a 71T as a replacement for the marelli (sp)? Advance curve ?

Thanks,

Peter.

Yep, it will work fine! But, before you just swap it out ... disassemble, clean, and check the Bosch unit for worn bushings. If any play more than 0.001" can be felt ... wobble at top or bottom of the shaft, replace the bushings with standard replacement from a local industrial bearing supply. The aluminum bodyshould be heated to 325-350 F for 20-30 minuted before attempting to remove old bushings.

Chill new bushings, heat dist. for easy installation. Lube with Bosch grease -- Pelican has it. Be sure to replace felt 'plug' in center of shaft, below rotor, and put a few drops of engine oil on it upon reassembly, and every time you change oil, check/adjust valves or sparkplugs. Good luck!

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Warren Hall
1973 911S Targa

[This message has been edited by Early_S_Man (edited 10-25-2000).]

Thanks Warren. pete.

I replaced the Marelli in my 1971 911T with a rebuilt Bosch from a 1968 911. It runs fine and now I know I can get tune up parts (rotor, points and cap) which were almost impossible with the Marelli. I am glad that I made the change.



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Bob Thayer
1971 911T
rthayer@hdrinc.com

Hmmm, the bosch distributor I purchased arrived today - It has a vacuum advance on it. I'm pretty sure (from memory)the marelli does not. The only numbers I can see on the Bosch unit are JFUDR6 and 0-231-169001. I'm assuming I just wasted some $. Does anyone have any ideas what I have just bought ?

That is a '72 T distributor, and the vacuum unit provides 10 degrees of retard at idle, for smog control. The overall advance, which is set at 6000 rpm (VERY briefly) with the vacuum hose off, is set between 31 and 38 degrees. Then, without the vacuum hose attached, the following values are checked to verify the advance curve:

At 1000 rpm -- 3.5 to 6.5 degrees Before TDC
1500 rpm -- 4.5 to 14 degrees Before TDC
2000 rpm -- 16 to 24 degrees Before TDC
4000 rpm -- 24 to 31 degrees Before TDC

At 900 rpm idle the spec. to be checked, with vacuum hose attached, is 5 degrees After TDC, +/- 1 degree.

The above data is from the '72-'73 factory spec. book.

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Warren Hall
1973 911S Targa

Thanks for the info. This does, I assume, mean that I am now the proud owner of a big greasy bosch paperweight.

Not unless you want it to be, Pete! It is usable without the vacuum retard, with the same specs for the advance curve I gave ... the only consequence of no vacuum retard is that your idle advance will be pre-smog at 5 degrees nominal BTDC. No effect whatsoever on the way your engine runs ... except that it will be more reliable than the Marelli! Good luck!

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Warren Hall
1973 911S Targa

Marvelous news! thanks again.

I replaced my stock 71T distributor with a 69 S Bosch on the recomendation of the guys at Doc & Cy's out of Indianapolis. Haven't really been able to get it dialed in yet. Any suggestions? Thanks, DaveJ 71T