TC Fast Idle Adjustment

B

Brian-Northampton

Administrator
Hi All,

In the past when tinkering and tuning my HS8 carburettors, I've never paid any attention to the fast idle / choke settings. they've always "just worked", often a bit lumpy, often needing to warm up on the drive rather than on the road, but non the less, they worked.

I've just finished rebuilding a set which I'll put on the car at the weekend, and I'd like to get this right. Now I can cope with getting the chokes even - that just takes two people, one in the car controlling the lever and me under the bonnet altering the cable.

But, what about the fast idle screw. Apparently this is supposed to be set at 1500 RPM at the point that the choke light just goes out when pushing the choke in. That sounds straight forward enough, but on the HS8 the screw couldn't be in a more difficult position.

Does anyone have any homemade tools, techniques etc for adjusting this screw. It can't be setup on the bench, it can only be done in-situ.

Short of employing children with small hands, how did Rover do it!

I'll post some pictures shortly to help you all see what I mean.

Thanks,
Bri.
 
OK I've taken some pictures.

This one is the view of the carburettors including manifold, imagine this on the engine. Remember also that there is very little room between the throat of the carbs and the inner wing - just enough for a slim air cleaner box.

mini-FastIdle1.jpg


this is the front carburettor taken from above, the fast idle screw is by the yellow arrow.
mini-FastIdle2.jpg


And a close up (a bit fuzzy but you get the picture...)
mini-FastIdle3.jpg


And one from 'underneath' which is difficult to get your hands into:
mini-FastIdle4.jpg


The fast idle screw also has a locknut to undo, and being so close to the heat shield, it is very very hot down there.

So......... all ideas are most welcome!

Bri.
 
If you look in the WM somewhere it shows you a spanner which does these, and which I had to make as an apprentice, and still have. Get an old screwdriver, cut off the blade at the end, then use one of the slipper pads from a rear caliper, drill a hole the same size as the screwdriver shaft, then weld to the bottom. Then cut the slipper to about 3/4" from the shaft, and cut and file a slot that fits a 4BA nut. Job done, and if done properly it'll last 34 years! (And counting) You can use it to back off the locknut, then screw the adjuster screw up, then re lock the nut.
 
Brian-Northampton said:
Have you got a photo of it Harvey?? :)
Click to expand...

Why would I need a photo? I've already got one............ :LOL:


PM me your email and I'll get a pic and send it to you. I'm not very good with all this computermebob stuff so I can't post it here but you're more than welcome to once you get it. I'll try and do it tomorrow.
 
Hi Brian,

I made one from a cheap flat 1/4" steel spanner (I think it was from an ikea flat pack). Heat with blow torch and bend head 90 degs. I ground the sides of the spanner head so it would fit into the tight space, easy! It also makes the mixture and idle screws much easier to adjust with this gadget.

Have fun,

Steven
 
Brian-Northampton said:
I looked in my manual, it wasn't obvious, but is this the one??

mini-CarbAdjuster.JPG
Click to expand...


That's it, but rather than the 90 deg cranked handle at the top, mine has a straight up screwdriver handle which means you can use it through 360 deg without the end hitting on things.
 
Thanks everyone for your replies and helpful information.

I often find that part of my problems (just one of them) is that in order to do some things, you often need to be able to weld ..... I will get a welder one day, and also a large collection of general crap that can be used as spares or turned into other things. It was when I was 'chatting' on messenger to Kev (Hermione) that I realised that somewhere in the mountain of crap (spare unsellable rover bits off eBay) that I picked up for a song a while ago, must have something that can be adapted.

Hurrah, I found this metal bar, bent in two places with a flat slotted bit on each end. Perfect. I've no idea what it was originally for, but it does my job. A bit of heat and bend the slotted end to nearly 90 degrees, dremel off the slot and new cut a ¼" slot for the screw. Tremendous!
mini-FastIdleTool.jpg
 
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