Mandatory AD: 2nd September 2010. Balancing Air Pressure.
This Mandatory Advisory applies to all TBI’s purchased Prior to 1st of September 2010 and applies to all such units irrespective of performance achieved.
In tests conducted recently it was found that if conditions arise causing a differential in air pressure between intake air and at the location of the TBI then problems can arise.
A mandatory modification to the TBI is required.
Rectification can be achieved by taking one of the following paths:
- For the cost of freight for the round trip send the unit back to the factory and once modified it will be sent back to you. Cost $100 for freight but you must contact the factory for instructions and paperwork.
- You may wish to modify the TBI yourself using the following instructions.
Modification Procedure:
Materials required:
- 2 off grease nipples ¼” with 28 threads per inch
- 1 off 3/32” Aluminum flush rivet
- Length of tubing to attach to each modified grease nipple.
Steps Involved:
- Using a 1/8” drill working from the top of the 2 grease nipples drill out the ball and spring in each.
- Undo the 6xM5 socket head cap screws to separate the 2 parts that make up the regulator taking care not to damage the rubber diaphragm
- Find the vent hole at the top part of the regulator and drill this hole out to 3/32”
- Apply the 3/32” rivet to this hole to block the old vent hole.
- Drill and tap a hole for the 1/4“ modified grease nipple with 28 tpi.
- Screw the modified grease nipple to place
- Turn the regulator cover over and grind/polish any protrusions flush to the surface. Ensure there are no burrs or sharp edges that may damage the rubber diaphragm
- Re-assemble the regulator and reinstall it to the TBI.
- At the intake air-box secure the other modified grease nipple
- Run a piece of AIR BALLANCING hose between the 2 modified grease nipples.
Future regulators and TBI bodies will have the nipple already attached.
Current TBI's are equipped with nipples one on the regulator and at the air intake of the TBI.Technical Support: Paul Chernikeeff.
Email: RotecEngineering@bigpond.com
Web : www.RotecRadialEngines.com
Web : www.RotecTBI.com
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Document as a pdf |
AD: 15th March 2010
EXTRA NOTES: 15-03-2010
- The full rich position should be set at a point which results in an 80 degree F drop from maximum EGT. This will almost certainly be at a lever position before the TBI rich full stop.
- The use of a return line is not needed even if using Auto gas. Just keep all the fuel lines fire sleeved and keep components as cool as possible.
- The full LEAN position is when all the tiny holes along the spray bar are at 12:00 or pointing straight up.
- The full RICH position is when the holes are position to the side or facing the side wall of the TBI throat.
- The TBI regulator should be located as close as to and as central as possible to the horizontal centre line of the TBI throat.
- The idle mixture screw is located on the side of the TBI housing and can be accessed using a 5mm ball Allen hex key.
- The mixture is factory set at 3/4 of a turn from being full closed. This should get you started but fine adjustment will be required to set the perfect idle mixture. DO NOT RAM THE NEEDLE HARD INTO THE SEAT IT WILL JAM AND BREAK OFF!!!!
- The ENGINE WILL NOT LEAN CUT while the engine is idling. This is because the idle fuel deliver jet is separate from the main fuel spray bar. So leaning the main spray bar (ie holes facing forward) will have no affect on the engine and it will continue to idle. To lean cut the engine you must first go to full lean and then raise the RPM until the engine quits. Or just switch of the mags like I do!
- The inclusion of a cockpit mounted TBI primer lever is highly recommended as it could be used to save your bacon should vapour lock or some other fuel starvation anomaly ever occur. In the case of vapour lock (very unlikely) you would simply jab or hold the primer lever on so as maximum fuel would flow through the regulator and quickly flush out the vapour lock.
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