Needles for HIF44 SU carburettors on 4.6 litre + Ride Height

[bogbrush]

I've just (six months !) replaced the whole drive train on my P5B. The one in my picture. Very pleased with it and now (April 2021) comes the "test drive shake downs". 
Can anyone suggest correct needles for HIF44 SU carburettors on a 4.6 litre P38 rebuilt engine using a 'fast road' cam?
We're thinking HFC needles to start with?
BTW, I now hopefully have a motorway cruising vehicle of 4.6 litre engine, ZF 4HP22 four-speed Volvo box, Jensen Salisbury 4HA 2.89 ratio limited slip back axle with disc brakes.
Amazing what boredom can produce !
Bob in Central Devon

[bogbrush]

 ............... and another thing - I meant to ask?
Even before all the changes to my drive train I had the car riding very high, probably due to changed springs/dampers or summat?
Can I fit 30mm or so spacers on top of the springs to drop the car further below the axle? If so, where/how do I get longer spring hanger "hoops"
In haste, Bob Rush a.k.a. Bogbrush Central devon.

[Phil Nottingham]

Some Series Land Rovers use longer U bolts - try Paddocks or similar

[thomashb]

Hi Bob,
I am curious which Volvo you pulled the ZF 4HP22 from.

How did you go de-electrifying it?

Did you do the work yourself or have a workshop do it for you?

Cheers,
Tom

[bogbrush]

Hi Thomas,
I probably can't be a lot of help? The box came ready-modified via Dave Ellis in Devon and had a rewelded bellhousing to fit the V8. We have not used the electric kick-down, doesn't seem necessary with a fast road cam and HC pistons.

ZF4HP22's I know were fitted to my Volvo 850(R) and others (LTV vans?). looking forward to a rolling road assessment in late August.
ATB,

[enigmas]

Just wondering about the ZF4HP22 trans in your P5. Did you retain the Volvo valve body or swap for a Rover variant?

[Roy of the Rovers]

Apr 10, 2021 17:29:18 GMT bogbrush said:

I've just (six months !) replaced the whole drive train on my P5B. The one in my picture. Very pleased with it and now (April 2021) comes the "test drive shake downs". 
Can anyone suggest correct needles for HIF44 SU carburettors on a 4.6 litre P38 rebuilt engine using a 'fast road' cam?
We're thinking HFC needles to start with?
BTW, I now hopefully have a motorway cruising vehicle of 4.6 litre engine, ZF 4HP22 four-speed Volvo box, Jensen Salisbury 4HA 2.89 ratio limited slip back axle with disc brakes.
Amazing what boredom can produce !
Bob in Central Devon

Hi Bob, sorry cant advise on the needles, I’d go Weber 500 on the 4.6. But is there any update on the shakedown testing and rolling road? Would love to hear how its panning out..

[Sam Bee]

If you want to stick with SU then either the HIF6 with suitable needles, which can really only be assessed either by trial and error or on a rolling road at a place conversent with SUs, or the 2 inch HD8 but same comment about needles. 

I have just had my P6B with HIF6 tuned up and now have BBW needles and springs changed to 'green'.

[enigmas]

Why not fit a wideband oxygen sensor & gauge to the engine/car, then record the A/F ratios/data at various speeds,rpm and loads, ie., idle, cruise, hard throttle, deceleration. Whatever needle is assessed and used initially becomes the default needle.

As it's an analogue adjustment method (fixed data points on the needles) you'll need to be thorough with your observations. Obtain an SU needle chart and change the needles incrementally at the pertinent stations until you arrive at the best fit for your engine.
A dyno won't simulate real world driving events, the above will if you have the patience to see it through.

Also consider the viscosity of the oil used in the dashpot (to slow the air slide rising too quickly) during hard acceleration as it'll have a bigger effect than changing air slide springs.

If it's all too much effort then there are digital Efi systems available that retain the look of the analogue SUs but are fully programmable and no longer rely on fueling needles, springs or oil viscosity.

www.pattonmachine.com/TBI-Main.htm

It may be worthwhile looking at this link to the MG Magnette forum (a login may be required) as there are examples of wideband oxygen sensors being used on these cars monitored via personal phones using wifi in real time.

www.mgexp.com/forum/mg-magnette-forum.27/air-fuel-ratio-findings.2540494/

[bogbrush]

Just to clarify. We didn't de-electrify the 4 ZF HP22 gearbox, merely didn't use the terminal, so no mechanical kick-down is available on the car either. No problem so far (1,000 miles after conversion) and looking forward to the rolling road assessment at Tipton-St-John tomorrow 25th August 2021. I'm hoping for 250BHP.

[bogbrush]

Thanks to all who responded and I hope to collate the info and make progress, but I'm an amateur owner and don't have the wherewithal for forensic attention I'm afraid.
Following on from my posted rambles - hopefully above - I comment further. I believe the following is a common P5B habit?

Rover stalling on pick-up when idling hot in traffic (normal temp).


As many of you will know, I have completed a revamp of my Rover P5B mechanics to include a slightly souped-up 4.6 litre P38 Range Rover engine coupled to a Volvo four speed auto box and a Jensen Interceptor back axle. It now burbles along the motorway effortlessly at 70 mph/2000 rpm. Magic.


But …….

Problem is, at standstill in town (traffic lights or queues) the car stalls when I depress the accelerator even slightly, and is a real sod to start again, feeling like fuel evaporation (I have an electric fuel pump mounted forward of, but on, the engine). Embarrassing. It restarts after a few cranks and about ten seconds. Then seems fine, but it happens again later. The spark plugs appear good – medium brown and dry. It does start mostly without choke and if used, the choke can be turned off straight away and the car will run. I have set tickover at around 700 rpm.


During this conversion I kept the original SU HS4 carbs but changed the dashpots to HIF dashpots in order to use spring-loaded needles (can’t remember why). Needle Type AUD 1536 have been fitted but we did not appear to have fitted the new sliding jets, they are still in my spares box. (Qu. This might be my issue?)

Am I asking too much of the two old SU carbs on a mildly tuned 4.6 litre modern engine? Or is it the wrong needles (if so what ones do I try other than AUD 1536?) Or do I need a Sun or Crypton tuner to look at it? (if so, where do I find one?) Or is it just that I need forensic tuning of the set up by an SU expert? (if so, where do I find one?)


I'm aware one of you recommended a Weber 500 so I may pursue that avenue.

Any constructive comments welcome. Bob in Wellington.

[bogbrush]

Sorry, forgot to confirm. The rolling road assessment resulted in a miserable  184 bhp at the wheels. But I'm happy with the performance generally. Bob in Wellington (not Boots)

[enigmas]

Apr 20, 2023 9:25:53 GMT bogbrush said:

Problem is, at standstill in town (traffic lights or queues) the car stalls when I depress the accelerator even slightly, and is a real sod to start again, feeling like fuel evaporation (I have an electric fuel pump mounted forward of, but on, the engine). Embarrassing. It restarts after a few cranks and about ten seconds. Then seems fine, but it happens again later. The spark plugs appear good – medium brown and dry. It does start mostly without choke and if used, the choke can be turned off straight away and the car will run. I have set tickover at around 700 rpm.

Your comment:
It does start mostly without choke and if used, the choke can be turned off straight away and the car will run.

Mine:
If it'll start (from cold?) virtually without using the choke, then it must be running rich. This would only become worse the more the engine heats up.

Your comment:
...feeling like fuel evaporation (I have an electric fuel pump mounted forward of, but on, the engine). Embarrassing. It restarts after a few cranks and about ten seconds. Then seems fine, but it happens again later.

Mine:
Why would you mount an electric fuel pump on the engine?
If the pump gets hot from radiant heat (sitting in traffic idling) then yes, the petrol will vapourize within the fuel lines. Carburettors aren't designed to meter gas/vapour. I'm presuming the fuel lines aren't metal.


Your comment:
I have set tickover at around 700 rpm.

Mine:
That's quite a low idle speed with a performance camshaft in the engine.
Idle speed should be set with the car in D if an auto

.

[bogbrush]

Many thanks for the helpful comments. Yes, I'll put the pump back on the side panel. I shall look out for HIF6 carbs, and tune accordingly. Cheers folks.

[thomashb]

Hey Bob,
What was the outcome here? I’m installing a 4.6 with SU HS6 carbs too. Would be great to know what you found works.