85-->87 motor conversion

[1000MileStylez]

I Have found an 85 engine for a really great price and my concern was if it is possible to convert the setup to be a 87 intercooled setup. Is it just bolting different parts on or is the block different? What im really asking is can this be done?

 

[GNVAIR]

Anything is possible, but basically in a nut shell
You need the complete intake, throttle body and plenum, fuel rails and coil pack brackets
all of the front engine accesories and brackets
as well as the 2 headers, cross over, down pipe and turbo
dont forget the intercooler and assorted plumbing.
The only things the are really the same between the 84-85's and the 86-87's are
crankshaft,
rods (86-87's came with SPS bolts)
heads
balancer and flex plate
driver side valve cover
cam sensor
front cover and water pump
maybe a few minor sensors. All else is different

 

[49-blues]

dont forget you will need to change the complete wiring harness and computer.

 

[gn85]

Done something like that..

Also, if you're planning on running the oil cooler, you'll need the oil cooler adapter on the front end. I didn't see anybody mention (might not have seen it), but you might need to make a hole for the oil return on the turbo as the 85s have the oil return in a hole in the intake..

I have an 85 block and an 87 block. I've used both on the 87 setup in my car. However, my block is a late 85 block that HAS the oil return line hole already there.

 

[1985BuickGN]

Was wondering if anybody that's done an '85 with an '87 engine knew how to get the dash tach to read correctly? I've got an '85 with an '87 and the dash tach reads about 2000rpm at idle and the laptop reads 800-900rpm at idle. Thanks for any help.

Paul

 

[gn85]

Stock dash is wrong...

The stock digital bar graph is typically wrong and higher like that. Mine also reads about 1500-2000 higher. I have a tiny tach that's wired in and it agrees perfectly with my laptop. Don't think it's a result of your 87 setup... which ign. module/coil pack are you using?

 

[1985BuickGN]

I'm using a complete '87 engine, wiring harness and ECM.