Sliding throttle arguement!
Discussion
Define Inferior?
Slide throttles (when engineered correctly) have zero restriction and offer a laminar flow capability to the incoming charge air. But if you size your conventional butterfly plate throttles correctly, and accound for the flow disurbance around the spindle, then there is no measurable difference really. The issue with slide throttles is always one of jamming and tollerancing the sliding parts to work smoothly across all temperatures. these days, dual roller barrel throttles are generally regarded as the best, but complex solution.
Slide throttles (when engineered correctly) have zero restriction and offer a laminar flow capability to the incoming charge air. But if you size your conventional butterfly plate throttles correctly, and accound for the flow disurbance around the spindle, then there is no measurable difference really. The issue with slide throttles is always one of jamming and tollerancing the sliding parts to work smoothly across all temperatures. these days, dual roller barrel throttles are generally regarded as the best, but complex solution.
Hiya
Depends on whether the butterfly/spindle restricts the airflow the engine is capable of using. Not throttle bodies but many moons ago we worked on a full race 948 Moggy Minor it ran a Cooper 12G295 head and a 649 race cam. It was restricted to a single 1 1/4" SU. With spindle and butterfly streamlined for flow it made 63 bhp at the wheels. We knew it needed more air so we removed the spindle and buterfly and blanked off the spindle holes, fitted the su piston with a throttle cable arrangement similar to slide throttle motorcycle/lawnmower/go-kart carbs. The new setup showed 67 bhp at the wheels.
Peter
Depends on whether the butterfly/spindle restricts the airflow the engine is capable of using. Not throttle bodies but many moons ago we worked on a full race 948 Moggy Minor it ran a Cooper 12G295 head and a 649 race cam. It was restricted to a single 1 1/4" SU. With spindle and butterfly streamlined for flow it made 63 bhp at the wheels. We knew it needed more air so we removed the spindle and buterfly and blanked off the spindle holes, fitted the su piston with a throttle cable arrangement similar to slide throttle motorcycle/lawnmower/go-kart carbs. The new setup showed 67 bhp at the wheels.
Peter
Sorry chaps,I should have been a bit more detailed with that.
He wants to use sliding throttles on a road car,a 70`s/80`s Alfa GTV.
His main use will be a half hour commute to work,half rural half town driving.
We both understand the principals,although he believes the sliding throttle will be suitable for his intended use.
Whereas I remember the sealing issues always being mentioned as Max did,that they are complicated in comparison and unreliable,but great to look at.
I spoke to a guy who looks after a few old F1 cars and historic racers for a collector/museum,I`m sure he mentioned that they were more picky about inlet design and not as flexible/controllable as a spindle arrangement.
Therefore my reasoning is that they going to be hard work in town and offer no benefit over an easier and more reliable system on the open road.
The current side draughts it was fitted with are almost dust and I suggested some throttle bodies,he suggested sliding and here we are.
Two beers on and a little nearer settling it in proper fashion with an arm wrestle.
He wants to use sliding throttles on a road car,a 70`s/80`s Alfa GTV.
His main use will be a half hour commute to work,half rural half town driving.
We both understand the principals,although he believes the sliding throttle will be suitable for his intended use.
Whereas I remember the sealing issues always being mentioned as Max did,that they are complicated in comparison and unreliable,but great to look at.
I spoke to a guy who looks after a few old F1 cars and historic racers for a collector/museum,I`m sure he mentioned that they were more picky about inlet design and not as flexible/controllable as a spindle arrangement.
Therefore my reasoning is that they going to be hard work in town and offer no benefit over an easier and more reliable system on the open road.
The current side draughts it was fitted with are almost dust and I suggested some throttle bodies,he suggested sliding and here we are.
Two beers on and a little nearer settling it in proper fashion with an arm wrestle.
Thanks all,we Googled sliding throttle bodies that evening and came to the Jenvey website which offers an explanation of all three types and convinced him against it any way.
The Solex carbs came dismantled,some parts are available but scarce and the bodies are clearly beyond repair.
New Weber replacements are still available surprisingly to us and with that in mind the Webers are now his choice.
Any way the fuel system is the least of his worries,
Having now seen the car my self in the flesh,it has what can be best described as gull wing rear quarters
The Solex carbs came dismantled,some parts are available but scarce and the bodies are clearly beyond repair.
New Weber replacements are still available surprisingly to us and with that in mind the Webers are now his choice.
Any way the fuel system is the least of his worries,
Having now seen the car my self in the flesh,it has what can be best described as gull wing rear quarters
PeterBurgess said:
Hiya
... so we removed the spindle and butterfly and blanked off the spindle holes, fitted the su piston with a throttle cable arrangement similar to slide throttle motorcycle/lawnmower/go-kart carbs...
Peter
Hi Peter! I remember when you came up with this seemingly hair-brained idea and Mick and I tried it out on the TR4 racecar. I think we left the butterflies in though. Throttle response was astounding but not very linear to say the least! All or nothing! Frightened Mick to death I reckon!... so we removed the spindle and butterfly and blanked off the spindle holes, fitted the su piston with a throttle cable arrangement similar to slide throttle motorcycle/lawnmower/go-kart carbs...
Peter
Geoff
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