Holley 02121NOS - Manual (Page 17)

Chapter 3 Routine Maintenance
3.1 Nitrous Solenoid Filter
When nitrous bottles are refilled they can become contaminated with debris, if the refiller does not have an adequate filter in
their transfer pump mechanism. Contaminants in the bottle will eventually become lodged in the nitrous solenoid filter fitting.
You should periodically (after every 20-30 pounds of nitrous usage) examine the mesh in the nitrous filter for debris.
To clean the filter, follow the following steps:
1. Close the valve on the nitrous bottle. Empty the main nitrous feed line.
2. Disconnect the main nitrous feed line from the nitrous solenoid. Remove the nitrous filter fitting from the nitrous solenoid.
3. Remove all Teflon paste debris from the solenoid inlet port threads and from the nitrous solenoid filter pipe threads.
4. Examine the mesh in the nitrous filter fitting for contaminants. Blow out debris with compressed air, if necessary.
5. Apply fresh Teflon paste to the nitrous filter pipe threads. Reinstall the filter in the nitrous solenoid.
6. Reconnect the main nitrous supply line to the nitrous solenoid.
3.2 Nitrous Solenoid Plunger
3.2.1 General Information
The seals used in NOS nitrous solenoid plungers are constructed from materials that are designed to be used with nitrous oxide.
When kept free from fuel contaminants or from overpressurization, they should provide trouble free performance.
You should periodically (after every 20-30 pounds of nitrous usage) examine the seal in the nitrous solenoid plunger.
The seals used in NOS nitrous solenoid plungers are designed to work at pressures up to 1100 psi. Exposing the plunger to
excessive pressure (whether the vehicle is sitting or in-use) can result in the seal in the plunger seal swelling or in extreme
cases, plunger seal disintegration.
NOTE: The seals are designed so that if they fail due to overpressurization, they will not leak, the valve will just fail to flow
nitrous oxide.
Swelling of the nitrous solenoid plunger seal will reduce nitrous flow (causing an excessively rich nitrous/fuel condition and a
loss of power).
3.2.2 Nitrous Solenoid Plunger Disassembly and Inspection
1. Close the valve on the nitrous bottle.
2. Empty the main nitrous supply line.
3. Remove the retaining nut from the nitrous solenoid.
4. Remove the coil and housing from the nitrous solenoid base.
5. Unscrew the stem from the nitrous solenoid base. Do this by double nutting the stem, or by using a solenoid stem removal
tool (NOS P/N 16665-SNOS). Do not use pliers on the solenoid stem. Damage to the stem will result.
6. Remove the stem, spring, and plunger from the solenoid base.
7. Examine the plunger seal for swelling. The seal surface should be flat, except for a small circular indentation in the center
of the seal;
A fuel-contaminated seal will protrude from the plunger and be dome-shaped. A fuel-contaminated seal may return to its original
shape if left out in the fresh air for several days. It may then be returned to service.
A seal, which has been overpressurized, may be dome-shaped, or the sealing surface may be flat with the seal protruding out of
the plunger. A dome-shaped seal may return to its original shape if left out in the fresh air for several days. It may then be
returned to service. A seal, which is flat, but protrudes from the plunger body has probably failed internally and should be
replaced.
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