Saturday, February 16, 2008


Carb heat muff, and other layout views.

Finding room for the carb heat muff has been quite problematic. It would have been much easier with a cross over exhaust, but heeding Vetterman's advice I opted for the 4-pipe. In order to make it fit I had to file some extra holes on the far side of the muff to allow for the nuts and bolts that connect the two halves of the pipe together. It was a long afternoons work but I am very pleased with the final result. It (just ) clears everything.

The EGT probes are all installed. Rather than have them stick out, I have elected them to face inwards so the wiring will be between the manifold pipes and the engine block. That is one of the next tasks.

This picture, from above, shows things are getting pretty tight behind the engine, but everything will fit in I am certain and I will retain good access to the oil filter. The oil pipe across the top is not currently connected. I am waiting for a 90deg. fitting to arrive from Aerosport Power to replace the 45deg. the engine was supplied with. I just do not believe it is possible to get a hose onto a 45 when an MT prop governor is installed.

The breather is installed and has a clear run down and ends just above the exhaust . The idea is that any oil mist coming down the breather is burned by the hot exterior of the pipe rather than becoming an oily mess on the underside of the aircraft. Also, it is hard to see how the breather could freeze up at the exit in this location. The concern I have is have I put the exit to the breather in a low pressure area so the pipe will be sucking on the sump. A similar installation worked well on my -9a.

(And 'yes' its cold in my workshop as you can see by my old coat.)

Here you can see that the oil cooler, although hung on the outside of the engine mount, still fits inside the cowl cheek profile, as does the carb heat muff.

Saturday, February 09, 2008


Oil cooler, oil lines and control cables.

Finally the oil cooler has come to rest.

I never did want to hang it in the baffles. It just seemed like more weight forward levering on the engine mount, and besides I am not sure there is room for it there in a -4.

The firewall was a possibility, but the material seems so thin and I would rather not drill it more than necessary. It would have to have been positioned very high up.

Here it is within the profile of the cowl cheek and the 3" SCAT hose has quite a short run. It is mounted entirely on the engine frame at three points.

From above it looks like this.

With the c/s unit for the prop it is becoming very crowded back here.

The oil lines to the cooler are not yet finalised but will almost certainly end up like this. It looks like I will need a new 90 degree fitting to get the oil from the engine to the cooler safely on its way. I have seen other folk cut into the prop governor bracket, but this does not make sense to me when it could come straight up.

You can see the control cable runs. The prop cable does a 270 degree turn. This was not to use up length but to ensure the tightness of the turn did not appear excessive.

So far I have managed to preserve some space around the oil filter. I just about know where everything goes and this will remain with room to access it when it needs replacing.

Wednesday, February 06, 2008


Throttle and Mixture linkage.

I have had some difficulty setting up the throttle, because everything need to be adjusted exactly, in order to achieve the full travel of the carburetor lever. Ideally the middle hole in the lever arm here would be 1/16th further up, or VANS quadrant would give you a tiny bit more range. I have an idea to fix it so you can be sure the carb is controlling the range, not the quadrant, but for that you have to go to the other end of the cable.

The mixture was much simpler in that it requires only about 95% of the quadrant travel to give full range here.

I am a bit concerned about the tightness of the bend in the mixture cable, though it runs quite freely.

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