complete engine change from '86 350 carb with '87tbi

[djp019]

Hello, I'm no mechanic, but I learn fast, so any help will be nice. I have a 1986 3/4 ton Scottsdale 4X4 with a 350 carbureted engine, as well I have a 1987 GMC Sierra 2 wheel drive with a TBI 350. What i want to do is put that engine in the '86, from reading I know I will need the wiring harness, an O2 sensor and the fuel pump, what i would like to know is what else I need, and how much work this is going to be, as well could I just take the throttle body plate off and put the carburetor on it? Any help would be appreciated, thanks in advance.

[Blue 82]

the vss (vehicle speed sensor will have to be installed in your trans. If the gear ratio or tire size is different you will need a DRAC (google it) or a handheld programmer like hypertech

Getting the converter to lock/unlock will be tricky if the transmissions are different (700r4 vs TH350C or TH400 in your 86)

You are gonna need the check engine light or perhaps the Gauges out of the 87
Do a search on "ALDL", it's part of the 87 harness

I'm sure others can add to the list



 


 

[Blue 82]

Here's the drac info
Not sure if it pertains to the 87's, but it may

http://www.tbichips.com/drac/

[djp019]

All good info, thanks, so I could pull the tranny and instument cluster from the 87 and inter change it in the 86, then there should be no problems right?

[Blue 82]

The 2wd tranny has a different output shaft than the 4wd

What's wrong with the engine in the 86?

[djp019]

Just old, been rebuilt a few times now, has 300000 on it, and the carb needs to be replaced, pick up the 87 for cheap thinking I could just pull the engine out and drop it in, like I said, I'm not a mechanic, but have messed around engines a little, didn't think it would be that hard. Guess I was wrong lol

[Blue 82]

Check the 87 block
see if it has a block off plate for the fuel pump
remove it and see if the hole is drilled for the fuel pump rod
if it is, drop the 87 shortblock in the 86 and buy another carb
you can use all your 86 stuff on the 87 engine
sell you old motor on Ebay/Craigslist along with the 87 parts
TBI heads bring decent $$$ from someone that needs em.
stuff a decent cam and chain in the shortblock and re-do the 86 heads and you'll be good to go

[the_legend_1981]

I would do what Blue82 said...it would be easier.

[djp019]

Thanks, I appreciate all the help, the more the merrier, I like to be well infomed, oh, and i don't know if this info will help but both trucks are 4 speed standard including a low range, not sure what kind of tranny they are though

[Blazin]

They are SM456 transmissions.

[Captkaos]

Does the 86 not run and you are taking the 87 apart?  Is the 87 a donor?
If the 87 is a donor, just take everything out of the 87 and put it in the 86 motors place.  Everywhere there is a wire or loom, follow it and get what is attached to it and swap it over.  If the 86 has cruise control, it will have a VSS in the cluster, other wise, just swap clusters (or the whole wiring harness if it is a donor?

[djp019]

yes the 87 is a Donner, and there is no cruise on either. So I will do just like you said, i will take everything attached to the harness and switch it over, I'm hoping it will not be to hard to do, I'm allways up for a challenge but as long as my 3 year old don't want to help to much lol. Again thanks for the info

[Blue 82]

If both trucks have the same trannys it should be a plug and play deal
Take a million digital pics of each truck
you are gonna need the gauges out of the 87 because they have the check engine light (or SES light)
See if anyone here has the GM wiring diagrams for the 86 and 87, compare the drawings before you start

[djp019]

Great idea, never thought of taking pics, I'm glad I joined this forum, you guys are great