This is great! I am not sure that for the average driver it is worth the effort to go without a damper, but it is good for max performance. Hammil's book is the bible. I wanted a friend to do this after a conversion from 2 carbs to 3-carb setup. Who knows if there is full lift of the pistons, or if they are lifting too fast. A video would tell. I love seeing the fuel mist when you really lift the piston. THANKS! P.S. how did you secure the camera so it didn't fall off or into the carb?
I think the idea would be to figure the max piston rise and coutour the exposed face like an airhorn facing into the incomming stream ... some people also open up the vacuum holes at the bottom of the piston... I don't know if this effects the full rise of the damper
very cool video... I've learned a lot I have a Datsun 240z... have you tried contouring the front of the piston ? ...
I'm not surprised the piston does not got all the way to the top since opening the venturi changes the vacuum at some point the flow and vacuum equalize near WOT
the dumper only prevents the piston to suddenly raise. The ammount that it raises depends only upon the spring. So, if you didn't remove the spring, it will go to right height, but if you hit the gas hardly, the piston will raise quickly and the engine will fail. The damper just prevents that.
@fmardito That's the common theory. But s you can clearly see, it does obviously NOT APPLY in this case! The piston does NOT rise too quick and the engine doesn't fail if I hit the pedal hard ( 1:30 )! Quite the opposite is the case... The engine's response on hard accelerator action got BETTER! . I can possibly get a transparent piston made to record throttle action.
But trust me, in this video I was VERY hard and FAST on the pedal (I think you can hear that)
@DeiMuddaSeiMudda ok! So, I think you may check if there is no excessive vacuum leak on the piston. If there is some vertical scratches on it, air coming from atmosphere may enter the chamber, causing the piston to be lifted with less power and causing the efeect you are seing. To this, you may disassembly the upper body of the carburetor, remove the damper and seal the holes of the piston using an electric tape for example.
@fmardito I've been working with SUs over 8 years now - it's OK. And I'm not the only one getting superior performance & throttle response with this modification. I know at least 3 others - and all are pleased with it.
Just because everyone says & writes the same doesn't mean it doesn't work in another way ;-) SUs seem very simple - they aint. I know they shoolbook theory of SU carbs. It's true. But also it's not the end of the story. Read Hammills book, you wont regrett it.
Then you leave it to fall. If it needs less than 3 ou 4 seconds to fall completely you may have a leak. See the university motors "matching su carbs..." video, it's the test I am describing.
@fmardito The carb is in a good working order. It just works in a different way to what they tell you in books etc.
Des Hammill goes into some detail regarding damperless SUs in 'The SU carburettor high performance manual' (ISBN: 1845840730). Interesting read! The only book I found that deals with this conversion.
Yes - it' not just about removing the damper & go, that will certainly not work. But with a few tiny & easy modifications it works. Great! Much better throttle response. Trust me!
The theory is that the piston should only get right to the top at full throttle and full revs. I am not surprised that it didn't get to the top. Show us some more experiments!
This is great! I am not sure that for the average driver it is worth the effort to go without a damper, but it is good for max performance. Hammil's book is the bible. I wanted a friend to do this after a conversion from 2 carbs to 3-carb setup. Who knows if there is full lift of the pistons, or if they are lifting too fast. A video would tell. I love seeing the fuel mist when you really lift the piston. THANKS! P.S. how did you secure the camera so it didn't fall off or into the carb?
rhodes19040 2 days ago
I think the idea would be to figure the max piston rise and coutour the exposed face like an airhorn facing into the incomming stream ... some people also open up the vacuum holes at the bottom of the piston... I don't know if this effects the full rise of the damper
patfurlan 3 months ago
very cool video... I've learned a lot I have a Datsun 240z... have you tried contouring the front of the piston ? ...
I'm not surprised the piston does not got all the way to the top since opening the venturi changes the vacuum at some point the flow and vacuum equalize near WOT
patfurlan 3 months ago
what did you do may i ask :) ?
evodean666 8 months ago
is it right when a carburettor damper raises to fast you get flat spots
Furious355 1 year ago
@Furious355 Yew. Thats right. Unless youdo something about it, likei did....
DeiMuddaSeiMudda 1 year ago
the dumper only prevents the piston to suddenly raise. The ammount that it raises depends only upon the spring. So, if you didn't remove the spring, it will go to right height, but if you hit the gas hardly, the piston will raise quickly and the engine will fail. The damper just prevents that.
fmardito 1 year ago
@fmardito That's the common theory. But s you can clearly see, it does obviously NOT APPLY in this case! The piston does NOT rise too quick and the engine doesn't fail if I hit the pedal hard ( 1:30 )! Quite the opposite is the case... The engine's response on hard accelerator action got BETTER! . I can possibly get a transparent piston made to record throttle action.
But trust me, in this video I was VERY hard and FAST on the pedal (I think you can hear that)
DeiMuddaSeiMudda 1 year ago
@DeiMuddaSeiMudda ok! So, I think you may check if there is no excessive vacuum leak on the piston. If there is some vertical scratches on it, air coming from atmosphere may enter the chamber, causing the piston to be lifted with less power and causing the efeect you are seing. To this, you may disassembly the upper body of the carburetor, remove the damper and seal the holes of the piston using an electric tape for example.
fmardito 1 year ago
@fmardito I've been working with SUs over 8 years now - it's OK. And I'm not the only one getting superior performance & throttle response with this modification. I know at least 3 others - and all are pleased with it.
Just because everyone says & writes the same doesn't mean it doesn't work in another way ;-) SUs seem very simple - they aint. I know they shoolbook theory of SU carbs. It's true. But also it's not the end of the story. Read Hammills book, you wont regrett it.
DeiMuddaSeiMudda 1 year ago
Then you leave it to fall. If it needs less than 3 ou 4 seconds to fall completely you may have a leak. See the university motors "matching su carbs..." video, it's the test I am describing.
fmardito 1 year ago
@fmardito The carb is in a good working order. It just works in a different way to what they tell you in books etc.
Des Hammill goes into some detail regarding damperless SUs in 'The SU carburettor high performance manual' (ISBN: 1845840730). Interesting read! The only book I found that deals with this conversion.
Yes - it' not just about removing the damper & go, that will certainly not work. But with a few tiny & easy modifications it works. Great! Much better throttle response. Trust me!
DeiMuddaSeiMudda 1 year ago
The theory is that the piston should only get right to the top at full throttle and full revs. I am not surprised that it didn't get to the top. Show us some more experiments!
BMC1100 1 year ago