Carb balancer for twin SU HS4's

[Caddy2000]

I need one of the above, as I'm currently tuning an MG B GT.

I've tried my Carbtune II, but the vacuume is so low that it does not register.
Thinking about the type that fits over the intake of the carbs. Gunson do one, but never been too impressed by their kit...

... Any thoughts out there?

Cheers,

Paul

[embee]

Sounds like you're connecting to the "gated orifice" (ooer matron) on the carb body used for the vac advance to the distributor. This is just upstream of the throttle edge when at idle so the distributor doesn't get full vac advance for idle, the vac only gets fed progressively to the distributor as the throttle is opened and the hole gets exposed to more vac downstream of the throttle blade.

You need to connect to the inlet manifolds somewhere, can't remember any detail for the old heeby-geeby though.

[Sid Squid]

Drill the manifold and put two adaptors in, then you can use your vac gauges.
I've got one of those Gunson things, (which is as you say cheap 'n cheerful), and it does work well enough for stuff like a 'B', (assuming you have a combined manifold).

[Caddy2000]

Sounds like you're connecting to the "gated orifice" (ooer matron) on the carb body used for the vac advance to the distributor. This is just upstream of the throttle edge when at idle so the distributor doesn't get full vac advance for idle, the vac only gets fed progressively to the distributor as the throttle is opened and the hole gets exposed to more vac downstream of the throttle blade.

You need to connect to the inlet manifolds somewhere, can't remember any detail for the old heeby-geeby though.

I'm not connecting to the dizzy take off, there is a vac take off on both carbs that attach themselves to the crank case (I think), I connected to them.

Drill the manifold and put two adaptors in, then you can use your vac gauges.
I've got one of those Gunson things, (which is as you say cheap 'n cheerful), and it does work well enough for stuff like a 'B', (assuming you have a combined manifold).

As above, there are already two take off points on the SU's - very low pressure, even when reving the thrupneys out of it (not advisible on an old engine that has not been tuned).
In the end I used my tongue: I placed each tub on the tip of my tongue to feel which had the most suction.
Took her out for a drive this evening and she ran like a dream, very very smooth. A bit lumpy on tick over though (650 - 700 rpm - should be 500 by the book, but it is old). Got her cruising at 70 with great ease