Not really, as it is under the intake manifod, but it is the bolt in the middle of the bracket that connects the motor mount to the intake. There is a large bolt at the end of the bracket, and two bolts on the other end of the bracket (and then the bracket turns down and connects to the motor mount), in the middle there is a bolt I think 10mm, it is the only one that is a stud.
I'm not exactly sure which bolt you are talking about, but I assume that you are referring to the plenum support bracket, which connects to the motor mount at the bottom, to the intake plenum at the bend of the "7" shape, and with a single bolt on the underside of the intake manifold:
In the center of the short leg (i.e., the one from the plenum to the intake manifold), there is a hole. That hole is for the fuel-rail support, which looks like this:
One end of this support threads into the fixed nut on the bottom center of the fuel rail, and the other goes through the hole in the plenum-support bracket that I think you're talking about. Thanks to Darren (Tifosi) and Eric (gnhl), I ordered McMaster-Carr part # 4403K722 to replace the fuel-rail support, which was missing part on my '85.
You can do this from the top by removing the fuel rail. To do so, I think that you'll likely need to remove the small hoses from the fuel rail to the injectors (depending on their age, it might not be a bad idea anyway). You need to be careful in removing these hoses so as to not damage the barbs on the injectors or the fuel rail. After disconnecting the fuel line from both ends of the fuel rail, I used a soldering iron with an X-Acto knife attachment to melt/cut the hoses off (being very careful). You also need to make sure that you use the right size hose in replacing the lines to the injectors (7.5 mm). I understand that there is no equivalent English-unit size.
Although it is a pain, you may be able to remove the plenum support bracket from the top. Remove the windshield-washer fluid bottle and the coolant-overflow bottle. You should be able to reach under the plenum with a socket wrench and remove the two bolts that attach the plenum support bracket (although you are working completely by feel). You can probably also get the bolt to the intake manifold this way as well. Compared to those two, removing the bolt that attaches the plenum support from the motor mount should be easy. If you can get the plenum support out of the way, support the plenum temporarily while you thread the fuel rail support into the bottom of the fuel rail (again reaching around under the plenum). Then, reinstall the plenum support bracket using the same bodily contortions. It's a real PITA, but I'm pretty sure that it can be done.
I just finished re-doing most everything on the intake side including rebuilt injectors with new hoses installed. Trust me, it is better to remove the plentum support (the L shapped thing), than to fool around with the fuel injector hoses unless you are going to remove the fuel rail - injectors attached and all. Those old hoses will be like hard plastic by now, rather than like rubber. You cannot possibly remove the hoses from the fuel rail and re-attach without getting into injector hose replacement problems. Bit the bullet and re-remove the support and then attach the double studded shock mount from underneath with the plentum support bracket off the car.
And yes, you can do the job from the top with the washer bottle and the radiator expansion tank out. I just did it. Since I had my plentum chamber off to replace the couplings with silicon connectors, I debated on installing the bracket first or installing the plenum first. Since it turned out to be much harder to line up the new coupler hoses than I would ever have expected, I ended up doing the plenum first and then installing the support barcket last. After you have done it once, it is a lot easier the second time.
I am in the middle of a head gasket job and in process of sending out my 4 injectors and cold start injector to be refurbed.
I noticed that your fuel rail is shiny!!! Looks great!
How did you accomplish this? Chrome plated? polished?
top half of air filter box
hood support rod
cap of radiator expansion tank (not pictured)
transmission shifter shaft
handbrake handle shaft
The 2 carpet hold downs which run up and down under the corners of the knee bolsters
The 2 carpet hold downs which run beside the doors
I installed a pair of chrome/stainless steel outside mirrors
Replaced cam cover nuts with polished stainless steel nuts
polished cam cover
Chrome plating to be done;
Looking at the possibility of disassembling the brake booster and having both halfs chrome plated - not sure if this can be done
without ruining the booster
Going to have the hood latch mechanish chrome plated
Going to find a chrome plated radiaror cap
Going to remove radiator tank top paint and polish and seal the brass tank top
Going to polish the brass fittings in the engine compartment