Expert: Rob Painter - 3/6/2011

Question
is it possible to put a northstar engine and trans(fwd) in a 1977 eldorado.  its already fwd, and also what r the combinations i could use?  will the northstar bolt up to the stock trans, and if not does anyone make an adapter to make that work.  thanks josh...

Answer
Hello,

Nice thought, however I doubt if you really want to do this for many reasons. First, you will suffer from lack of sufficient horse power to pull that big car around.
Even when the 4100 was introduced in 1982, there were power issues and that was a bigger engine than the Northstar.
I don't even know if you could get all the sensors to work properly (like the speed sensor). Your speedometer has a cable and the Northstar set up is electronic. Your catalytic converter is not set up for an O2 sensor and everything, as for all the wiring harnesses are completely different.

The Northstar or any of the aluminum engines are a real issue because they cannot be over heated what so ever! It's almost impossible to find a good used Cadillac aluminum engine!
The other issue you might run into even if you could find an adapter for the transmission, the Northstar is married to it's transmission via the computer (BCM). Let's say you used your transmission. The engine won't run right because it does not see the signals coming from the transmission to complete the engine signals to put the computer in closed loop. in order to run properly. Your fuel injection with the Northstar will not work properly etc.

Nothing is ever impossible, but what it would cost you for this conversion is far more than you would get out of the vehicle. In fact, you are actually devaluing your vehicle by putting such an engine in. Even if you change the gear ratio, which you will be required to do as well, you will sadly be disappointed with the performance. this is a nightmare waiting to happen!

The last good engine in the full size front wheel drive Caddys was the 1981 4-6-8 361CI when the single wire was removed to make it run on 8 cyl only. It was cast iron and was a throttle body fuel injection.

See, the small FWD Caddys were designed completely different involving the complete power train, not just the engine and included the differential and transmission.

1982-1985 full size fwd Eldos and Sevilles were blessed with the 4.1 (4100) and there were not very happy owners of these because of engine problems. Many came with a knock from the factory and they too like the Northstar were notorious for blown head gaskets and worse from an over heated aluminum engine! Cadillac over the last 39 years has reaped in billions of dollars for repair and replacement of the 4.1, 4.5, 4.9 and the Northstar! All aluminum junk!

If you over heat your 77, the absolute worst is that you may blow a head gasket and commonly not that. If you do it to the aluminum engine and just seconds of over heating, not minutes, it can cost you well over a thousand for repair, if the engine can even be repaired.

The Northstar or any FWD Cadillac engine is not a good choice for your 77. Your best off trying to modify what you have or find a complete with harnesses and computer, transmission and differential from a 1981 Eldo, go through it all and you will have a very enjoyable ride!

All this advice is from a guy who has owned 20 Cadillacs and serviced thousands of them. I really hope you reconsider this adventure, because you will not be happy with the end product.

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