I'm swapping motors in my 81 Grand Prix. The Buick V6 is coming out and a 1977 Buick 350 is going in. I'm keeping it stock; no performance upgrades at all for now, aside from dual exhaust. All of the computer & smog stuff from the V6 will come out & I'll only leave what I need. I'm switching my factory gauges from idiot lights to gauges. I'm keeping the factory AC. I have and am keeping cruise control. See the attached PDF... I sketched all of the connections on my motor - vacuum, electrical & other. And I labeled each for reference. I researched 1977 vacuum routing and I think I know what went where. That's on the left in the attached file. Once the 350 is in, I'll reconnect only what I need, mostly based on LARRY70GS's post in this thread. I'd just like a few extra sets of eyes on this. Anything wrong, any suggestions on what to do differently? I appreciate it.
Sorry, I'm not much help on the smog stuff. If you found a 77 service manual, I'd expect it to have the proper routing of the hoses. I'd probably loose most of it if it were mine. I'd ditch the EGR and all the other hoses and only hook up a PVC, power brake booster and vacuum advance to manifold vacuum. I'm sure the AC internals are run off of vacuum and I'd assume they are manifold as well.
One more thing, depending on your transmission, if it has a vacuum modulator, it will need a vacuum line as well.
Starter is on the same side in the same position, and physically fits, so all those wires will fit as well as the starter itself. All you really need to do wiring wise is add around 8" to the hei hot wire (thick pink wire). I did the 231 to 350 swap myself when I was 16 as my first swap. Keep every sensor and their plugs, they'll all work.
I did a V6 to 455 in a 1975 Skylark (X-body) and I just tugged on the HEI wire and got enough slack to hook it up. Everything else worked except the AC top bracket didn't line up but a V6 to 350 should work. I even used the V6 torque converter and man, that little car would scream!
Most of the original routing came from the attached 1975 routing diagram. Even though I don't plan to do all of that, I like knowing how it was supposed to be originally. It just helps me think through things. I have the HEI wire from the 350 so I won't have to use my V6 wire. And the trans vacuum modulator runs to a port on the intake behind the carb, so I've got that accounted for. The only thing I don't have on my diagram is the vacuum line for the TCC switch I intend to use on my previously computer-controlled TH350C transmission. I just need a ported source for that. Thanks for the comments..
