Alternate rockerfeed mod for B44/B40G/C15G

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kommando
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Alternate rockerfeed mod for B44/B40G/C15G

Post by kommando » Wed Jan 06, 2010 1:42 pm

GEdit by MM: Well done kommando, the topic that sporned this write-up can be found here.

Where you do not have the correct inner timing cover to allow the take to the Rocker you can take the oil feed instead off the pressure release valve, the idea came from the Mark Cook mod but does not require a late timing cover. You can drill and tap the valve body 1/8 BSP, discard the spring and ball, tap the hole going to the sump 2BA and insert a 2BA grub screw. I then screw a 1/8 BSP 90 degree fitting with 4mm quick release into the valve body and take the rocker feed off there.

Note, do not attempt this mod to C25/B25's or early C15/B40's with the plain big end, the loss of pressure at the big end will destroy it. Also prior to the C15G and B40G the pressure relief body will not take the 1/8" BSP tapping safely so you will have to design engineer a different housing.


Pressure relief bodies, modified and unmodified and the fitting, you drill through the relief body from the inside using an 8.7mm drill and tapped 1/8" BSP

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The lower of the 2 holes is drilled 4mm and tapped 2ba for a 2ba grub screw, it runs down at an angle.

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Setup on a bare crankcase

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And on a completed installation, used a semi clear tube so you can see the oil has found its way

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At the same time, fit an oil filter in the oil return route and if possible do the mods to increase the piston oiling, ie increase the diameter of the drain holes next to the cam follower holes and also reroute the drain to the sump to first go to the inner crank space.

Copied from the tech tips pages

Now that there's more oil flowing to the head, we want to help more of it get out of there, so we've got to allow more to drain down to the cases. Take the two holes in the case that pass oil from the pushrod tunnel (not the cam follower holes! see Figure 3-C for location - sorry about the blurriness), and open them both up to 13/64" (one should already be that size). Now chamfer them, and also chamfer the pushrod holes so oil will drain there easier. Also, take the two holes at the bottom of the case (timing side) which allow oil to drain into the sump and block them off. (Figure 3-D) Drill a 3/8" hole (horizontally) which allows oil now trapped on the timing side to pass through to the primary side and drain down the big hole there. (Figure 4).


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