This may be old hat to a bunch of people on this board, but I figured I'd post it anyway for anyone who is installing or reinstalling their intake and exhaust manifolds. If there's an easier way to do this, please let me know so that I don't waste time in the future.
The two manifolds bolt together around the heater box that the carb sits on. There are two nuts on the top; close to the manifold, and two longer bolts that bolt from the bottom on the steering box side of the firewall. Leave all 4 of these nuts / bolts very loose. Don't even finger tighten them; leave 4 - 5 threads loose.
Get the new gaskets lined up, and hold them in place with some spray adhesive - some people like to use RTV, or copper-based sealant. Put the rings into the intake manifold if you have the 235 intake. The metal or shiny sides of the gaskets go towards the manifolds, or away from the engine. The manifolds are easier to install if the gaskets are not slipping all over the place or falling onto the ground.
Use the dowels on the end (some people have converted these to studs) to get the manifold close and in place. Install the 2 outermost bolts / clamps - the ones just inside the studs. Thread them just enough to keep the manifolds from falling off the engine. Once you get the manifolds onto the motor, you can fiddle with them and make sure that everything is aligned properly. Grab the intake manifold, and lift it up (give it a shake to make sure that the two manifolds are somewhat separated).
At this point, I put a jack under the exhaust manifold; just enough to hold it in place directly lining up with the exhaust ports. Be careful to keep the manifold level, and not to tip the top or the bottom away from the head. Use a 2X4, a dowel, or a bunch of connected extensions between the jack and the manifold - whatever is handy.
Start with the intake manifold and maneuver it into place, making sure that the rings are in place and the ports align. Thread the two innermost bolts and clamps. Since the jack is holding the exhaust manifold in place, and you are holding the intake manifold in place with a free hand, use your other hand to start the bolts and to :barely: snug them. DO NOT TIGHTEN AT ALL YET. Do the two inner clamps and then do the same with the outermost clamps. Don't tighten them at all yet! Look at the alignment and make sure that everything looks right. If you need small adjustments, you can jiggle the jack, or use a screwdriver between the two manifolds to tweak things into place.
Install the two remaining bolts / clamps and barely tighten them.
Starting with the innermost two bolts, start to tighten them 1/8 to 1/4 of a turn at a time. Move to the next pair of bolts out, and then to the ends. Don't try to shortcut this because if you do the manifolds will bind and you won't get a good seal to the head. I tried mounting the manifolds about 8 times before I figured out that you have to go slow and tighten the bolts a tiny bit at a time; going through all of them in sequence. If you skip this and it works for you, consider yourself either lucky or extremely skilled
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After you get the manifolds torqued (25 lbs for the two innermost bolts and 18 - 20 for the others) you can tighten the 2 nuts and 2 bolts on the heater box. Tighten these in sequence, too; a little bit at a time until things are snugged up. If you skip this, the box will bind and you will not get a good seal at the gasket. If things bind up, you can tap the top of the heater box with a hammer to free it up.
Finish up with the two brass nuts that hold the exhaust pipe on the exhaust manifold.
Refit the carburetor and re-install the choke and throttle lines. Reconnect the fuel line and any vacuum lines.
Start the motor and check for leaks. Leaks are easiest to find before the motor gets hot, so take this opportunity to run your hands around the manifolds looking for leaks. If you wet your hands it helps to feel the leaks.
This method worked for me perfectly. I tried other methods of tightening the bolts, and I never got a good, leak-free fit. I was convinced that the manifolds were warped until I removed them and checked them with a straight edge. The key is to keep things very loose at the start and then to tighten them up very slowly, in sequence.
Hopefully this helps shave some hours off of someone else's job.
