Small block Olds fuel injection rail/intake from '75-'81 Seville

[Fast355]

The box on the distributor is to trigger the Bosch ECM. (When you put a new pick-up coil in the dist, remember to remove the pin inside the lower box. Be careful with it.) The original throttle bodies had what is called a "Choke Heater" When it was cold this would allow more air through for RPM increase. They had a bad habit of failing and Hi rpm all the time. The old Bosch system would hesitate on a quick accel and Caddy Eng. said this is Normal. On the Caddy engines (Not Olds) the intake gasket would draw air and run higher rpm. See below fix!
If you ever put an intake gasket on an Olds engine, Use sandpaper to rough up and clean up the head AND Alum and Cast iron intake. Carb or Brk cleaner on all surfaces to clean it. Punch 3 holes in the Bottom of the valley of the intake gasket pan 1/2 inch. Use GOOD SILICONE SEALER ON BOTH SIDES OF THE INTAKE GASKET. Easpecially the Water Ports. I had numerous buy-backs for coolant leaks on intakes. I would run a very thin bead around each port and between each lower side of the port. Use silicone for the China walls and you have to do it pretty fast so the sealer won't skin over. (I've heard of some cutting the intake pan off or using a Olds Diesel intake gasket. The Pan prevents SOME HOT oil to the bottom of the intake and allow it to run cooler. I suggest you leave the pan intact but 3 1/2 holes in the bottom of the valley)
If your building an Oldsengine of the mid 70's to mid 80's, do yourself a favor. Pull the heads and "Clean Up" the port bowels. They are full of extra material and heavily restrict FLOW. The Ex are the worst I saw. I would also back cut the valves, it really picks up flow at low lift. I would never use the small port heads in the 90's. They are swirl port and if you look at the timing tables in the ECM you'll see Very low numbers. It's because it is efficient but only there for fuel econ and no power gain.
Check ALL the push rods for carbon build up. They get restrictive near the EGR. If you use a EGR, make a alum plate and cut the EGR passage to half. It will help with Hi Flow EGR valves that got into production.
Dont use 10-40 oil in an Olds. Use 10-30 Synthetic. If you don't keep up with the oil changes, the Rocker arms will fail on cyl, 3 and 5 and 4 and 6. The push rods will plug with carbon form this also.

I have experience with those 80s 307s. I would never not run the swirl ports in the factory application. I had a 1988 Cadillac Sedan Deville Brougham with the 180 HP Vin9 307, 200r4, and 2.53 gears. Cruised 70 mph just above idle and would knock down 25+ mpg on every long road trip I took it on. Off-idle and low end torque was very strong, just not much HP. I think the cam fell of about 3,500 rpm anyway, so no real need to rev it high either. 4,000 rpm in 1st gear was about 60 mph!!! That olds would have been so much better with TBI on top.

Also not sure what you mean by the timing advance. The 307 Vin9 in a Cadillac had one of the most aggressive advance curves I have seen in an engine. The WOT spark started at 28* BTDC @ 1,200 rpm and ended up at 34* by 2,800 rpm. Part throttle advance ran as high as 60* BTDC. The distributor was set at 20* Initial as well.