I checked it over before I installed it to adjust the floats and idle speed to standard (floats a little off out the box) and checked what rods and jets were in. Compared to the 1406 Performer carb its a little more difficult to change the rods. Not a lot, but things are a little more cramped at the top of the carb so its more fiddly. The piston that the rods fit into doesn't quite clear the screw of the little screw-down cover plate without a bit of care taken which turns a 2 minute job into a 10 minute job.
Here's what I mean:
1706 Performer, loads of room here to swing the cover plate out the way and get the rod and piston assembly out easily.
1805 Thunder AVS has a different shape surrounding the choke, almost reversed. There is a high lip that goes across the centre which means to get the rod and piston out you have to completely remove the cover plate and screw which adds a bit of time, and adds to the risk of dropping bits down the carb. I much preferred the simplicity of undoing the screw a couple of turns and swinging the plate out the way.
You can also see above the Thunder has got dual fuel feed (one on either side) unlike the performer which is UK driver side only. Seeing that I already had the fuel line plumbed in for the drivers side this didn't bother me but is useful to know. I don't yet know how the car will behave in hard turns but with the previous carb it would bog rich on very hard turns and hard stops.
One benefit of running an AFR in the 13's at cruise instead of waving around between 14.5:1 and as high as 16:1 is that the engine runs 5 degrees cooler. Previously I was seeing that at prolonged periods of 30 or even at 40mph when I'm forced to do 2000rpm to get a smooth ride the temp gauge needle would creep over 90°C to approx 95°C. Its hard to tell exactly as there are very few increment marks on the gauge. It now sits just below 90°C in all conditions, dropping a little more if cruising over 60mph.
We brought the throttle pedal end stop up a couple of mm to prevent the throttle cable being stretched and the butterflies being damaged. This is a bit awkward, its just an M12 bolt through the front of the footwell but needs someone in the footwell and a helper with their hands stuck between the headers and the brake servo in the engine bay. The travel required on the cable on the 1805 for some reason seems to be about 3 or 4mm less than on the 1406. Not quite sure if this is actually a difference between the carbs or if something has changed on the cable route somewhere. Might look into this a little more.
Still a couple of other things to give attention to - I happened to look down the primaries with the engine running at idle and I could see a couple of drips coming from the primary nozzles which means the throttle is open a little too much at idle. The transition slot should appear square when the throttle is closed but mine isn't perfect as it needs a more throttle to idle because of the cam.
The engine runs on (diesels) ever so slightly, just one or two turns after switching off the key so these two things are likely related to the idle throttle position just being a hair too much. I think there is some leeway on the idle speed - now that the carb responds properly to changes in tune, I can revisit my timing and then coming back to the carb again. Perhaps I could add another degree of timing at idle which would allow me to close the throttle a little more. I'm not currently 100% confident in my cheap timing light so I've borrowed a good snap-on one from a friend to verify the timing.
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