Tuning Twin weber
- Thread starter gordinir8
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Tuning Twin weber
I think that unless the carb upgrade was part of a "tuning package" it would be a complete waste of time and money. A basic tune would include cylinder head, carb, camshaft and exhaust
I guess that in theory if you got the jetting right it should run ok but that is normally a job for setting up on a rolling road. I think that any increase in hp would be mainly imagined after a lot of work and spending possibly £500+ on engine mods and parts. Much cheaper to buy some Abarth stickers and go faster stripes
If you are set on spending lots of cash I would start with uprating the cylinder head and a sport camshaft.
Much cheaper to buy some Abarth stickers and go faster stripes
I have recently added floor mats with Abarth badge on and put two nice metal Abarth badges on rear fenders, next step is a roof checker stickers.
That gave me some confidence and i think i am a little faster now. Maybe it is better to start from a sporty but not too extreme cam. I am just collecting info and decide what to do later. I guess my car is free of trouble now, everything operate normal and i am looking for something to mess with, like the oil cooler installation which i have on the works
Thomas
The twin 38 and 40 are massive carbs for this engine. In order to set them up for a fast road car they are restricted to reduce the flow into the head.
On a normal car they would have to be restricted further. Back in the day the dellorto fzd 30.24 was a popular choice for these engines, but they are rare and a bit pricey.
To get a refurbished twin 40 carb you would be looking at £200 + without the manifold. Take that money and give it to an engine rebuilder and ask him what he can do to the cylinder head, the gains will be bigger and it allows you to upgrade the carb at a later date.
If you have a spare head and don't mind a bit of experimenting you could try fitting a motorbike carb. Read this:
http://club126uk.co.uk/blitzracing/tuning.htm
On a normal car they would have to be restricted further. Back in the day the dellorto fzd 30.24 was a popular choice for these engines, but they are rare and a bit pricey.
To get a refurbished twin 40 carb you would be looking at £200 + without the manifold. Take that money and give it to an engine rebuilder and ask him what he can do to the cylinder head, the gains will be bigger and it allows you to upgrade the carb at a later date.
If you have a spare head and don't mind a bit of experimenting you could try fitting a motorbike carb. Read this:
http://club126uk.co.uk/blitzracing/tuning.htm
Hi Thomas, you will find that most people with the 500/126 who run with a Weber 38/40 have tuned engines of one level or another. To use a DCOE 40 for instance you will need to reduce the venturi size to maintain the mixture velocity into the engine, also the jetting would have to be adjusted (reduced) to suit the engine tune. On a standard engine you may never get it to run correctly without spending (a lot of) money on a rolling road, and then it may still not run correctly. Remember the 40 is a twin choke and unless you have a Panda 30 head all the carb will be doing is using two chokes to pass (a lot of) mixture into one port - not very efficient on a standard engine - tuned engine yes with a high flow rate. If you wish to progress try a weber 30 DGF from a 126 BIS, that would give you the option of changing jetting with fixed venturi sizes (both 23mm) and if you use a pancake filter you will get the noise too
Ian.
If you wish to progress try a weber 30 DGF from a 126 BIS, that would give you the option of changing jetting with fixed venturi sizes (both 23mm) and if you use a pancake filter you will get the noise too
Ian.
I would not recommend a Weber 30DGF from a Fiat 126 Bis as they have a reputation for falling apart and being very difficult to get parts. Apart from that , just like Fiat decided to restrict the 500R engine by fitting a 24mm carb, the Bis carb has tiny 19mm venturies. However the Weber 30DGF from a Panda 30 engine is not restricted, has 23mm venturies and is more robust not to mention already jetted for a 650 engine.
A more traditional Weber twin choke tuning mod is to use a Weber 30DIC carb which were only ever fitted to the 850 Sport Coupe & Spyder so scarce but they do turn up on ebay sites. Avoid the US spec one though. They have the same flange mount as the DGF and either 21/23 or 23/23 venturies. The new style inlet manifolds coming out of Italy make a neat package. Being a progressive twin choke you can drive on part throttle like a single carb or bury the noise pedal to get the full monty
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I would not recommend a Weber 30DGF from a Fiat 126 Bis as they have a reputation for falling apart and being very difficult to get parts. Apart from that , just like Fiat decided to restrict the 500R engine by fitting a 24mm carb, the Bis carb has tiny 19mm venturies. However the Weber 30DGF from a Panda 30 engine is not restricted, has 23mm venturies and is more robust not to mention already jetted for a 650 engine.
A more traditional Weber twin choke tuning mod is to use a Weber 30DIC carb which were only ever fitted to the 850 Sport Coupe & Spyder so scarce but they do turn up on ebay sites. Avoid the US spec one though. They have the same flange mount as the DGF and either 21/23 or 23/23 venturies. The new style inlet manifolds coming out of Italy make a neat package. Being a progressive twin choke you can drive on part throttle like a single carb or bury the noise pedal to get the full monty
I have some of those carbies in various states of repair.
Could be a future project once the car is up and running.
