For those of us that have heads with the mystery "threaded and waiting" boss on the left rear?
I noticed that the threaded hole is in a great location for an extended magnetic plug.
The magnet will hover just above the drain trough that exits the head, and to protect the lower thin scavenge pump from direct hits of damaging steel.
This is best installed during a head dissection or porting job of course, but it CAN be done to an assembled head by packing greased foam into the cavity, and being Very careful to collect and dab, rinse etc all possible drilling debris afterward. A small file will beburr the outlet hole that you drill.
The Bolt-Plug is Stainless, and with a bonded hydraulic seal. The Magnet is heat rated to 302 degrees F,.... and it's a very strong N45.
The drill bit will just skim the existing threads and blunt them only slightly, and as the bit self-aligns while drilling deeper. The head block is quite solid and thick in that area of the extended bore. It almost seems to have been cast with some feature like this in mind?, but I have no clue about that. Some heads may only have a solid cast nub there, and are not further machined. But I think more than 80% of our heads have the tapped and faced hole there.
These are $35, and I'm including a high quality cobalt drill bit (also made USA). Some repeated shots of cutting fluid is recommended, since it's a fairly deep hole that is being drilled out. You won't need to re-chase the threads with a tap afterward. But you can pre-clean and contour the remaining threads with another spare bolt as you like, and after compressed air or wire brush etc. very easy. The threads are common M10x1.5 and several Cannondale bolts you have laying around from your motor drop will do the trick.
Magnetic Head Plug
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cannondale27
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- Joined: Wed Mar 10, 2021 10:41 pm
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Canniboomer
- Posts: 0
- Joined: Wed Mar 10, 2021 10:41 pm
Yep sure, will do...
Check out the same plug here doing double-duty as connected to a Head temperature sensor:
The copper ring just replaces the seal. The heatsheathed sensor extension cable goes to the Trailtech Speedo or Tach, instead of using the normal Trailtech sensor that cuts into the coolant hose. With that setup, you can still use the Cannondale Status Lights to warn of coolant temp -- and when the red light blinks at the temperature as pre-set in the maps, you can glance at the SpeedO temp readout and compare liquid temp at the front of the head to metal temp at the rear of the head. It should be interesting to see the comparison, and to watch the head temp on various machines. We know some motors can generate "glowing red" headers without overheating the coolant -- so I think it will be useful to monitor the digital readout and warning LED on the Trailtech also.
Of course, the extended magnet plug is not needed, and just a short bolt will do...but this is an available higher-tech option if you are wanting to add a backlit 12V SpeedO at the same time.
Check out the same plug here doing double-duty as connected to a Head temperature sensor:
The copper ring just replaces the seal. The heatsheathed sensor extension cable goes to the Trailtech Speedo or Tach, instead of using the normal Trailtech sensor that cuts into the coolant hose. With that setup, you can still use the Cannondale Status Lights to warn of coolant temp -- and when the red light blinks at the temperature as pre-set in the maps, you can glance at the SpeedO temp readout and compare liquid temp at the front of the head to metal temp at the rear of the head. It should be interesting to see the comparison, and to watch the head temp on various machines. We know some motors can generate "glowing red" headers without overheating the coolant -- so I think it will be useful to monitor the digital readout and warning LED on the Trailtech also.
Of course, the extended magnet plug is not needed, and just a short bolt will do...but this is an available higher-tech option if you are wanting to add a backlit 12V SpeedO at the same time.