Beyond the 3 pin connection from harness is there any other compatible problems with an 85 bosch distributor being used in an 83? I have been fighting a bad idle till it warms up and it dies unless I have the foot on the gas for the first minute or two. I have been searching the archive since realizing I replaced my chrysler distributor with a bosch from an 85. At the time I thought it was an 84 but now realize it was a b230. Could this be the problem. If they are not compatible then why does it run at all?

from the archive, this link got me thinking about this.
http://www.brickboard.com/RWD/volvo/524716/220/240/260/280/distributor_compatibility_b230_b23.html

The '81-'84 uses Hall sender 1-234-211-018, which only works (right) with ICU 0-227-100-018

'85-'87 use a different Hall-ICU pair.
Your '85 Hall may be pulsing the '84 ICU but not to its liking.

The '88-'89 Hall-ICU numbers change again according to my "SAVE" parts book.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

It seems like I should be able to just replace the hall sensor on the distributor rather than the whole distributor. Except one on ebay shows the vacuum hose thing on the 81-84. If thats needed then I guess the whole thing has to go. Thanks for the help.

replacing the hall sensor is not easy. I destroyed one doing the "pry up the aperture wheel with two screwdrivers" method shown in the green book.

83/84 use LH 2.0 The 85 is an b230 this is the first year of the LH 2.2,the 84/83 use an hall Sensor,were the 85 does not.look up the two.

I think the cars all use the distributor's hall sensor until the CPS (crankshaft position sensor, on the bell housing, reading the flywheel) was introduced with LH2.4 in '89. If the '85 didn't use the distributor's hall sensor, there wouldn't be any cable in the car's wiring to hook up to the distributor.

But there might be some differences in the distributor -- perhaps with the advance weights, etc., to distinguish the LH2.0 of the '84 with the LH2.2 of the '85, but this is just speculation.

I don't think there are any weights inside the LH distributors. They simply distribute spark, so anything that will fit will do that.

Not all LH cars are the same. LH2.4 controls spark timing (including advance) via the ECU programming, using the CPS (on the bellhousing) as a baseline. But those using the distributor pickup for the baseline ignition timing need some mechanism to control advance curves -- LH2.0 and 2.2 can't do that as an electronic algorhythm.