You can use the 2.1 throttle body and AFM with air filter connected to
your Digijet wiring without modification.  The 2.1 air box won't fit the
1.9 OEM mounting because of the idle booster switch(s) (if you have air
conditioning and/or power steering), and the 1.9 coolant hoses.

I put a 2.1 into my '85 Westy and I used a complete 2.1 intake system
... from the snorkel in the D pillar all the way through to the intake
runners.

You'll want to use a Digijet (vacuum type) distributor as well as the
Digijet ECU.

Using the 2.1 exhaust, assuming it's in good shape, is a good idea.

Mike
'85 Westy (2.1)

Brendan Slevin wrote:
> So I acquired a free 2.1 that was rebuilt 30k ago to put in my 84.  I was
> planning on doing the conversion the way I've read by basically putting the
> 1.9 WP/cooling pipes on, keeping the 2.1 plenum and using the 1.9 t-body.
> What I didn't plan on was getting ALL the other bits for the 2.1, ECU,
> harness, airbox, exhaust, etc.  Can I run the 2.1 ECU, t-body and airbox and
> such in place of the 1.9 bits?  I know I'll be putting on a new 1.9 WP and
> keeping the cooling system the same, and removing the 2.1 oil cooler.
>
> Brendan
>
>
>