F355 upper plenum

This is a normal procedure.

Remove the plastic beauty cover for the coolant and power steering.
Disconnect 2 vacuum lines (small one closest to the cabin, and one near the rear).
Disconnect the oil breather lines.
Loosen the metal rings until they are on the verge of separation on the bottom of the plenums.
You should then be able to wiggle off the plenums. If they're stuck, you need to loosen the metal rings further.

 

It’s easy to remove the plenums as a unit but a PITA to reinstall them. Your asking if you can take the plenum top halves off, I have seen it done, and yes you’d need to be super careful with the bolts.

It’s actually quite easy to freshen the Plenums whilst it’s in the car. If you do split the Plenums you might want to get the gaskets for reinstall.

 

Remove them as an assembly, rebuild and pressure test them.
Here is a 8k mile 355 with new gaskets installed was not good enough. Took some tweaking to correct. 20+ year old plastic warps.

Test your intake system and retest. Have not seen many that did not leak

 

I hate this job.

 

You will need new gaskets. they will break. Get a back brace lol

 

They are easy to get off as a unit and hard to get back on. I take the clamps and spacers right off.
Personally I would clean really good and paint new lines like lots of us have in the car.
Then when you do your next engine out powder coat them.
This is def not impossible, just get used to dropping the parts.
I would not split them as I felt the allens were harder to get at then the clamps and spacers

 

Then I would still take them off as a unit.
It depends on how the engine out guy positioned the clamping screws. I set mine so that I can get at them not sure how yours are turned