A question for V8 Stromberg CDSE specialists

[1984V8110]

After rashly stating a month ago on this forum that my 1984 V8 110 had been a paragon of reliability for 20 years I suddenly had a problem with one of the stromberg 175CDSE carburettors that was resolved by putting a new kit through it.

While doing that I obviously had the carb off, and saw the white 'teeth' on the inlet manifold side of the carbs as shown in the photo I hope appears below.

The workshop manual refers to these, but I do wonder whether they are a milder version of the throttling that was applied (I understand) to de-tune the V8 in the Stage 1 Series III V8s. Is there any advantage in removing these, and, in any case what are the 'teeth' for?

162314

Any advice gratefully received!


Michael

[Tote]

Maybe to modify the airflow out of the carb to get better atomisation, I doubt that they would provide much restriction. Maybe a factory Hiclone[bigwhistle]

Regards,
Tote

[1984V8110]

Maybe to modify the airflow out of the carb to get better atomisation, I doubt that they would provide much restriction. Maybe a factory Hiclone[bigwhistle]

Regards,
Tote

Thanks Tote

The same thoughts crossed my mind - especially the Hiclone thought!!

Michael

[Blknight.aus]

its a restriction plate,

the teeth create turbulance which does a couple of things

1. it damps the incoming airs velocity by forcing it into a turbulent flow pattern

2. it helps with distributing that fuel air so you get a more thorough mix.


try this...

run the back edge of a comb through a bath of water with it just at the surface (holding it by the teeth)

now do it with the teeth in the water.

similar concept.

[Tote]

So Dave,
If it was removed would the increased flow offset the better mixture and atomisation from the teeth or at the end of the day would you not notice any difference?

Regards,
Tote

[Blknight.aus]

yes and no...

the main desired effect IIRC is to damp the air flow on sudden throttle openings which is supposed to help with the mixing of the fuel and the air preventing flat spots during sudden losses of manifold vacuum.

(damping meaning to reduce the rate of change)
While the engine is pulling air quickly vorticies are setup behind the teeth, when you open up the throttle as the vorticies collapse they produce a short low pressure which draws a little more air through helping the carby do the carby thing. When you close the throttle off (or engine RPMS rise) the vorticies start up again and promote turbulant air flow mixing the fuel a little better and preventing the fuel from falling out of the mix and lining the intake.

If you're not driving in a style that warrants them then they probably make no difference, however, I quietly believe that they work because they help maintain smooth flow through the carby and not because of any "hiclone" effect they have.

[1984V8110]

Thanks to both Tote and Dave

I think you have clarified things for me.

One final consideration has just crossed my mind and which supports the suggestion that removing them would have little or no effect is the fact that the diameter of the aperture defined by the inside of the 'teeth' is still significantly larger than the mouth of the Stromberg carburettor at the throttle butterfly, so it would be unlikely that the 'teeth' would act as a limit on the flow of the air/fuel mixture.

The subtext of my original question was that I was trying to work out why the rated power output of the V8 in the 110 is significantly lower than is claimed for a similarly aged Range Rover (approx 110 bhp for the 110 vs 125 -135 bhp for the RR depending on source) with the same engine/carb combo. But I now see in the RR parts catalog that the same restrictor plate is shown for the RR, so the restrictor plate cannot be the source of the difference. Perhaps there is a camshaft difference causing this (and when I rebuilt this engine I seem to recall installing a RR camshaft) and/or the quoted bhp figures just represent higher rpm and hence peak power for the RR (although the figures I see show peak power at around 4000 rpm).

Thanks once again


Michael

[101RRS]

The FC101 3.5 does not have any restrictor or sharks teeth and is rated at 120hp in 12v form. The only difference to the same RR engine is the exhaust - the 101 exhaust manifold is designed for more torque at lower revs and tapers off at higher revs.

As far as I know - all LR carb 3.5s have the same cam shaft

So differences in power comes down to restrictors/shark teeth, 24v or 12v (in the case of a 101) and exhaust design. Nor real differences in basic engine.

Garry

[PhilipA]

My impression always was that the sharks teeth main function was to help idle stability as the turbulence caused reduced fuel pooling in the manifold.
Regards PhilipA