New SU HIF44s Fitted - A couple of Issues

Raggylad · Post by **Raggylad** » Mon Jul 15, 2013 2:57 pm

Well, I've finally got around to it and replaced the knackered 30 year old Strombergs on my Landrover 110 with a pair of new old stock HIF 44s.

I've got them up and running with the engine at the correct idle speed and have (roughly) set the mixtures so that the engine runs OK-ish. However:

- I cannot get the balance set correctly. I'm using a Gunson Carbalancer. The problem is that the idle adjustment screw on the RH carb won't screw 'in' far enough - when fully in, the bottom of the screw just touches the throttle lever and won't go in the further 1 1/2 turns that is the initial setting given in the LR service manual. The LH carb idle screw has a full range of adjustment; the lack of adjustment on the RH carb makes it impossible to balance.

- The choke mechanism (mainly on the RH carb) is really stiff, to the extent that when the knob is pulled out, the choke jams open and won't close when the knob is pushed back in. The net effect is that (a) I can't set the fast idle speed and (b) the choke doesn't work on cold start.

The vehicle normally runs on LPG, so neither of the above is a major issue keeping me off the road - but I would like to get them sorted.

Any ideas ?

Thanks.

Nick

ChrisJC · Post by **ChrisJC** » Mon Jul 15, 2013 6:48 pm

Most odd. I wonder if something is bent, maybe even the body of the carb?, so things are binding.

Chris.

Raggylad · Post by **Raggylad** » Wed Jul 17, 2013 3:16 pm

Choke issue solved by lubrication and careful adjustment.

That still leaves me with the RH idle screw/can't balance issue.

DaveEFI · Post by **DaveEFI** » Wed Jul 17, 2013 5:17 pm

Does the butterfly close fully?

kiwicar · Post by **kiwicar** » Thu Jul 18, 2013 9:28 am

Hi
Have you got poppet valves on the throttle plates of these carbs (I am assuming these aren't actually new carbs just new to you), If the answer is yes to the poppets and no to being new carbs then solder the poppets shut and chop off the springs, it is nearly impossable to get a stable idle with the poppet valves in place once the springs have gone week (ie more than 10 years old carbs).
Best regards
Mike

Raggylad · Post by **Raggylad** » Thu Jul 18, 2013 10:38 pm

The carbs are unused new old stock. They came with poppet valves on the butterflies, but I replaced them with new plain butterflies from Burlen (and, yes, they were put in the right way around !).

A colleague who has worked on Rover V8s professionally in the past suggested:

- removing the offending idle screw to check for burred threads, etc and replacing with new from Burlen if the thread is damaged. And if nothing is wrong with the screw:
- swopping over the screw from the working idle adjuster on the LH carb. If that works, replaced the faulty screw; if not, scratch head and start looking at throttle mechanism.

I'll try these over the weekend.

Thanks for all the suggestions, though.

DEVONMAN · Post by **DEVONMAN** » Thu Jul 18, 2013 10:52 pm

My suggestion would be to loosen/centralise the plain replacement butterfly and hopefully this will allow the shaft to rotate further towards the closed position and as a consequence this will allow the idle screw to actually touch the throttle stop lever.
Just a thought.

Regards Denis

DaveEFI · Post by **DaveEFI** » Fri Jul 19, 2013 8:08 am

I'm not clear what the problem is. The idle adjustment screw is in the carb body and pushes a lever which is keyed onto the spindle.? Is the butterfly not closing enough - or not opening enough at idle? Is the screw in a very different height from the other carb?

kiwicar · Post by **kiwicar** » Fri Jul 19, 2013 9:17 am

Hi
I think Denis might have spotted the fix! I did the same on my bug catcher on Sunday and sorted part of my "reving up after burn out" problem, all I need now is a baffeled tank and that won't happen this year

Best regards
Mike

Raggylad · Post by **Raggylad** » Fri Jul 19, 2013 8:36 pm

DEVONMAN wrote:My suggestion would be to loosen/centralise the plain replacement butterfly and hopefully this will allow the shaft to rotate further towards the closed position and as a consequence this will allow the idle screw to actually touch the throttle stop lever.
Just a thought.

Regards Denis

Good idea, I'll give it a go. Thanks !

Raggylad · Post by **Raggylad** » Fri Jul 19, 2013 8:41 pm

DaveEFI wrote:I'm not clear what the problem is. The idle adjustment screw is in the carb body and pushes a lever which is keyed onto the spindle.? Is the butterfly not closing enough - or not opening enough at idle? Is the screw in a very different height from the other carb?

The problem is that the idle screw only just touches the throttle lever at max 'screwed in' adjustment. It doesn't offer any idle adjustment as it cannot go in further and move the lever. The screw isn't at a noticeably different height from the other carb.

I'll try the suggestion 2 posts up to see if that is the root of the problem - effectively the butterfly not quite closing properly.

DaveEFI · Post by **DaveEFI** » Fri Jul 19, 2013 11:23 pm

Any possibility you've fitted the spindle wrongly when changing the butterfly?
Or the lever?

Raggylad · Post by **Raggylad** » Sat Jul 20, 2013 8:37 pm

DaveEFI wrote:Any possibility you've fitted the spindle wrongly when changing the butterfly?
Or the lever?

I don't think so. These were brand new, unused (albeit old stock) carbs. All I did was swop out the butterflies fitted (which had poppet valves) for plain ones from Burlen.

I've got the offending idle screw out (took rather longer to do than writing about it - one of those awkward little jobs !) & nothing appears wrong with it. Next step is following the suggestion above about re-seating the butterfly.

DaveEFI · Post by **DaveEFI** » Sun Jul 21, 2013 12:04 am

I though from your initial post the problem was you couldn't open up the butterfly enough to balance it with the other one? The butterfly not being centred would give the opposite effect - you couldn't shut it down far enough.

DEVONMAN · Post by **DEVONMAN** » Sun Jul 21, 2013 7:30 am

DaveEFI wrote:I though from your initial post the problem was you couldn't open up the butterfly enough to balance it with the other one? The butterfly not being centred would give the opposite effect - you couldn't shut it down far enough.

I believe the butterfly is shut but he needs to rotate the spindle so that the lever touches the adjustment screw. Centralising the butterfly may allow the spindle to rotate slightly in the desired direction.

Denis