Pressure valve kicks in at 78 lbs of pressure. Replaced valve still occurs

indicates reed/ poppet valve problem
possibly a broken spring in a head

check/ replace the non return valve in the line from the compressor heads to the tank

most likely a problem reed /poppet valve in the compressor heads

Sounds like the check valve is leaking. It's in the water line between the pump and the pressure switch

should be 4-5 nuts/bolts.
remove bolts, pull cover off. (pry edge with small screw driver if too tight or tap around sides with rubber mallet to loosen.
pull off all old gasket from cover and top seal area on head.

clean up all parts and wipe dry.

apply the new gasket. see image below.

make sure the 3 rings inside the cover are replaced, then reinstall.

do not over tighten.
torque spec
1.8L engine - 43-78 in-lbs

1.9L engine - 50-100 in-lbs

2.0L SPI engine - 71-97 in-lbs

2.0 Zetec engine - 54-70 in-lbs

to convert from inch to foot pounds just divide by 12

On 1990-93 Accords, tighten the bolts to 29 ft. lbs. (40 Nm) on the first pass, 51 ft. lbs. (70 Nm) on the second pass, then tighten the bolts to their final torque of 78 ft. lbs. (108 Nm).

Maybe your unloader valve is stuck or damaged. This is found in the switch assembly and if it is faulty you should be able to hear a constant hissing noise from the switch .

Clean the flame sensor with a piece of sand paper or a piece of emery.

Timing belt/chain may have been put it slightly off time, when motor rebuild

The pressure bleed valve is not working when the compressor shuts off. It is supposed to drain pressure from the compressor air line to the check valve and pressure regulator switch so that the compressor restarts with low pressure in the output line.