22 replies to this topic

[carbon]

Rally Mini 1000 - standard 1.5" SU with AAU needle and K&N cone filter

 

1293 Traveller - Manx spec 1.25" twin SUs with AAA needles and standard metal airbox with standard filters

Curious to know what level of power output your 1293 is running.

 

The AAAs can feed a lot of fuel when at top of travel. And are the HS2 internals vizarded?

[luismx123]

can someone explain the term "vizarded" to me? cheers :)

[WillCarter]

can someone explain the term "vizarded" to me? cheers :)

 

There is a book called

"Tuning the A-Series Engine: The Definitive Manual on Tuning for Performance or Economy" by David Vizard. This is where the term comes from. 

Here's a link to his book, it's definitely worth getting: https://www.amazon.c...y/dp/1859606202

Edited by WillCarter, 06 July 2018 - 09:12 PM.

[carbon]

can someone explain the term "vizarded" to me? cheers :)

As above, the term 'vizarding' describes the modification of SU carbs to improve air flow in the quest for additional power. There are a number of stages described by David Vizard in his book including:

1. shortening the butterfly screws and thinning the throttle shaft

2. blending the carb body in the areas where dashpot piston meets the main venturi

3. streamlining the underside of the piston

4. Blending in throttle 'bridge' using epoxy or similar ramps

 

Vizard also usefully states that 'if you do modify your carb don't assume the existing needle profile is anything like correct'. This is worth remembering, particularly if you progress to stages 2 and 3. My experience here with HS2s suggests that:

2. blending the carb body in the areas where dashpot piston meets the main venturi will weaken mixture at full throttle high speed conditions

3. streamlining the underside of the piston will richen the mixture, particularly during full throttle acceleration

 

I've not yet tried the epoxy ramps...

[luismx123]

 

can someone explain the term "vizarded" to me? cheers :)

As above, the term 'vizarding' describes the modification of SU carbs to improve air flow in the quest for additional power. There are a number of stages described by David Vizard in his book including:

1. shortening the butterfly screws and thinning the throttle shaft

2. blending the carb body in the areas where dashpot piston meets the main venturi

3. streamlining the underside of the piston

4. Blending in throttle 'bridge' using epoxy or similar ramps

 

Vizard also usefully states that 'if you do modify your carb don't assume the existing needle profile is anything like correct'. This is worth remembering, particularly if you progress to stages 2 and 3. My experience here with HS2s suggests that:

2. blending the carb body in the areas where dashpot piston meets the main venturi will weaken mixture at full throttle high speed conditions

3. streamlining the underside of the piston will richen the mixture, particularly during full throttle acceleration

 

I've not yet tried the epoxy ramps...

 

ah thanks for that. kinda what i was hoping for!

Any idea how much extra power one could gain from this? The mini i might be picking up soon has a 1275 with an hiff38 i believe. Used webers cost like 300pounds....or a hiff44 is fairly easy to get, but yea...

[Arthy]

Running a MED/ITG filter setup on twin HS4's on a maniflow inlet with my 1330. Did cut the throttle shaft/butterfly screws as per Vizard, pulls very well! 

 

Ran these carbs for over 2 years now and has been faultless! 

[racingbob]

hif44 vizard modded. med substack. itg filter. that's what's on mine very happy

[minitravellerman]

 

Rally Mini 1000 - standard 1.5" SU with AAU needle and K&N cone filter

 

1293 Traveller - Manx spec 1.25" twin SUs with AAA needles and standard metal airbox with standard filters

Curious to know what level of power output your 1293 is running.

 

The AAAs can feed a lot of fuel when at top of travel. And are the HS2 internals vizarded?

 

 

I am still building the car so I've not had it on a rolling road for set up as yet. No idea of power so far - all I know is that it'll run well :)

 

The carbs are built to Manx spec but Mervyn Johnston (The Tollyhommon Flier) here in Northern Ireland - similar to Vizard I believe.