Howdy folks.

I recently picked up a '83 244 with the M46. (I have a '80 245 as my daily driver ~50 miles round trip daily.)

So I was researching specs on the '83 and noticed that the '83s came with the Volvo/Chrysler ignition but the '84s had the Bosch ignition. Correct me if I am wrong, but the Chrysler ignition has a white-top dizzy cap. This '83 has a red-top cap, if I recall correctly. (Car is parked at my friend's house, 50 miles away.)

My questions are:

How are the '83 and '84 engines different for the M46 equipped models? Are the internals really that different to account for the lower compression ratio in the '84? (Piston size, etc.)

Does the different ignition system (e.g., Bosch versus Chrysler) really make a difference in power since the AW70 equipped models are only 7 hp different between both years?

Is it possible (easily done) to swap the Bosch ignition into a Chrysler equipped car since it has a red cap now?

Thanks,
Bryant

Around April of 1984, There was a change in Oxygen Sensor (to a 3-wire, heated type) with a corresponding change in the ECU. The "1984.5" model uses the same ECU as an '85, even though one is a B23 and the other is a B230

My 1984 was built in February of 1984 and has the single-wire O2 sensor and red distributor cap.
--
Mike F - 1984 244 DL - 317,000 miles
Original engine, transmission, drive train, starter
Undergoing reconstructive surgery with POR-15

1972 142 S - The Yellow Brick - 135,000 miles
All stock except for Weber Carb. B20B engine. M40

Thanks for the responses...

This is what I found in regards to the differences between the two years:

1983
M46,AW70
10.3:1 compression ratio
B23F LH-Jetronic
107hp@5400
127ft-lb@3500

1984
M46 only
9.5:1 compression ratio
B23F LH-Jetronic
111hp@5400
136ft-lb@2750

AW70 only
10.3:1 compression ratio
B23F LH-Jetronic
114hp@5400
133ft-lb@3500

I still don't have an answer to the question regarding the internals of the M46 equipped '84 B23F... I'm wondering how those differ from the '84 AW equipped and the '83 motors.

But the info shared here about the ignition definitely is helpful!

Interesting information here. Now my 83 is looking like it needs a for sale sign while I look for that 114 hp 1984 engine ; )

I had issues with my AMM quality. I had 3 of them and all were pretty much crap. So I opted for switching out the ECU under the passenger sidewall and repinning the AMM to accept the 86 LH2.2 FI. It made my idle perfect and car runs great.

I had the chrysler distributor originally and finally found a substitute for it. The bosch distributor in the 84 is the 14mm shaft compared to the smaller shaft in the later years. Different rotors fit the two different bosch distributors. I soldered a square connector in place of the round.

The Chrysler white top distributor had two issues while on my car. One the thin tin foil like ground ripped and then the wire lead with the round plug had a short causing the car to buck like crazy and almost stranding me until I figured out a way to tie it to one side so the short was fixed.

So what kind of difference are we talking in power between 107hp and 111hp? 2% gain which can be lost with a low tire or a dirty air filter?

the bosch dist did not come out until 85. then, volvo made a replacement available for the earlier chrysler dists with a round connector. you can put an 85 dist into an earlier car if you change the connectors.

the 84 b23 auto had 10.? comp. compared to the 9.5(?) compression b23 manual. i forget the exact compression numbers, but the hp is higher for the automatic.

another difference is the ignition control unit. they plug and play but are internally different between years, trans and dists. good luck, chuck.

There was a Bosch replacement distributor for the Chrysler unit. I had one on my daughter's 1983 244. I bought it on ebay, and it had the round electrical connector. Your car must have one of the desirable Bosch replacement distributors.

The automatic transmission B23F powered 1983-84 240s had 10.3:1 compression while the manual transmission equipped cars had 9.5:1 compression.
--
john

John - thanks for the info on distributors, I had never seen a Bosch with the round plug. It makes sense that if Volvo was offering them as service replacements, they would fit the Volvo-Chrysler harness connector.

Did the lower compression engine for manual trans arrive in 1984? My 1983's driver manual and the Green Books for that year (New Car Features - USA & Canada), states the B23F engine as being 10.3 compression ratio, and with 107BHP at 5400RPM.

The Green Book shows that the auto trans engines (of 1983 anyhow) had a sticker on the T-belt cover labelled 803, the manual trans was 802 so they differentiated them in that way, but I found no other mention of differences.
--
Bob: son's XC70, dtr's '94-940, my 81GL, 83-DL, 89-745(V8) and 98-S90. Also 77-MGB and some old motorcycles.

I no longer have an owner's manual for 1983 240s, so your information must be correct. The B23F compression difference must have come with the 1984 models.
--
john

The Bosch distributor uses a rectangular connector to plug in the ignition wiring, the Volvo-Chrysler (white cap) uses a round one. If you have a brick-red cap and a rectangular plug, you have a Bosch distributor. Volvo may have started installing these partway through the 83 production run.

I wasn't aware the '84 had a lower compression ratio than '83, but if so, that could account for the BHP difference. Those were early days for the LH system and Volvo may have been modifying various tuning parameters to meet emissions rules.

There have been some comments here about failures of the V-C distributor, but the one in my early-production 83 has been operating for 30 years now (170k mi) with no problems. Got a new rotor and cap for it in the parts bin but have yet to install them.
--
Bob: son's XC70, dtr's '94-940, my 81GL, 83-DL, 89-745(V8) and 98-S90. Also 77-MGB and some old motorcycles.