need advice 1991 735 donor car...

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jk ska

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Hi, and thanks for taking the time to read this.
A few months ago I came across a 1973 e9 that is straight an mostly rust free.
I knew little about the vehicle ,but a little internet research confirmed my gut feeling that that I would forever regret not purchasing it. The car is in fairly nice shape but shows all the normal wear of a car that spent a large portion of the last 40 years being used as a daily driver.The engine runs but carburetors are in sad shape. I plan to strip it down , do a complete body work/repaint, new interior ,and engine and transmission swap. I have no experience with BMW's and will undoubtedly be coming to this forum for help on a regular basis as I get further into the project...However my reason for posting today is the following:
my internet research when purchasing the car indicated that the highest stock HP in the US on a 3.5 liter engine was found in the 1991 735 (208 hp) and within days after buying the e9 I stumbled across that exact car ,with a strong engine, in my neighborhood and for a price that is best described as ''just get it out of my yard''...So now it is in my yard and I need to strip it and
get it to the scrap yard. So my question for those of you that have done all this before is: what other parts from the 735 drivetrain (other than the engine) should I consider saving. This car has an auto trans that I have no interest in, but I want to make sure I do not regret getting rid of the differential, axles, brakes etc.
On a side note, does anybody know if the engine out of the 735 will fit under the hood of the e9 with the stock intake manifold? It looks like a close fit at best.
Thank you all. Jk (in Hawaii).
 
Great engine for your swap, keep the ECU of course. I have seen the original manifold used but an early e12 manifold with the log style plenum and C runners gives it a very correct look. I am even ditching the Motronic dizzy for a conventional one. You can use that coil or an older black standard coil too.
 

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b35 intake

Fits just fine but you would have to replace the e9 brake booster with one from a Tii and shorten the brake booster mount by approx 3 1/2". The easiest years to install are from '88 and '89 (sfdon please confirm this is correct ) due to motor mount changes in subsequent years.

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You are right on for the date- 88,89 are the easy ones.
 
If one day you are brave enough to do a rear coilover modification, you can use the rear control/trailing arms and wheel wells from the donor 735 but you will need a smaller differential and crossmember, e.g., from an e28. You would also have to use the calipers and rotors from the 735 in that case.

The differential is too big to bother with for the E9. The rear crossmember is too long. The axles, if I remember correctly, are too long. The driveshaft is probably too long but since they are 2 pieces I like to keep a bunch on hand in case different parts can be Frankensteined during a swap.
 
Hi all; and thanks for all the valuable info...The island is Maui. Again thanks for the help. Jk.
 
Go see Carl in Paia - he has a csi with a blueprinted engine and megasquirt.
 
Spotted Carl and his green 3.0 in town a while back, and we had exchanged phone numbers. I was off Island for a couple of months but we finally connected a few weeks ago and he came over for a visit with his car. He will clearly be a great source of information and motivation for the project ahead...Thanks.
 
Wish I was a little closer... have the '73 CS with five speed and LSD, and a donor '87 735i next to the garage... "ran when parked" but now beyond economic restoration. Will be watching this thread!
 
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