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Opeler
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Many thanks to oldopelguy for tip about that Italian carb seller. Now I'm assured I need dual carbs. :)
My engine plans have changed a bit also. I'll probably have a chance to buy a ported 1.9l head which has been used for racing purposes. However, valves are still normal 42/37 and porting is not extreme. Well, I'll see that tomorrow, but with that price I guess I want at least try it. With a well chosen camshaft street driving should be quite far from impossible... I hope.

But about dual carbs. My primary concern is the room needed for installation. I really wouldn't like to cut and weld the car to have them fit. (Well, there is also another reason. I couldn't do it by myself and I'd have to find someone to do it.)
Are downdrafts dual carbs easier to fit than sidedrafts? Are sidedrafts possible at all without cutting metal? I made some measurements and came to conclusion the downdraft carbs would probably fit if the hood opener bar would be cut (like in http://www.fortunecity.com/silverstone/healey/116/motor-2.html ). Or maybe carbs would fit even with that on, but not air cleaners.

Making intake manifold would probably not be a problem. I could have them custom made. The minimum lenght of sidedraft manifold would be about 4 cm because shorter transition from the circle of carb end to the head port would be very difficult to do with a "wire cutter".. I'm not sure that is the right word for that machine.
Anyway, I guess 4 cm would maybe not be the optimal choice from the viewpoint of torque. Right?

I also thought about putting carbs into different angle than 180 or 90 degrees but that sounds quite stupid because it would probably make the room problem only worse.

Good pictures about dual carb setups, tips about "designing" intake manifold, experiences about fitting duals, etc. are welcome!


Lasse H.
 

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Carbs side or down

Comes down to what lengths you are willing to go to.

The shorter the intake, more the torque (and power) is affected, as you know.

You can squash a fairly large amount of intake into that bay.
Keep all bends as long as possible and you can get away with almost anything.

Dual sides on opposite side of engine, long intake runners.

There is plenty of room in that bay.
That EFI? plenum, air filter and additional rubbish is all quite large for a small engine.

Dual carbs, trouble mounting them, some additonal trouble tuning them. If you are not going to spend the time tuning them or someone else tuning them stick to the single carb.

Down or side. vacum or mechanical secondaries
All comes down to what effort you are willing to go to.

You could have a couple of down drafts off to the intake side+front of the engine, much like the early F1's or go the flat wide intakes over the engine like some current boat engines & they produce balls o'torque.

What do you want from this machine?
 

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dual carbs are always nice to have, especially the sound that they produce in the car. the hardest thing would be to keep them tuned together.
 

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Both OpelDean and Nobody have built dual side-draft setups, and have gone to some lengths to document how it was done. There are at least three companies that have built manifolds to allow dual side-drafts to be fitted to a GT. Some of them require extensive intrusion into the heater-box, and some don't.

I'm still waiting for the worlds slowest body-man to get my GT put back together, but I have a nice pair of Irmscher intakes (and and Irmscher thermostat housing), and a nice pair of carbs waiting in the garage. Do a search on dual carbs and you'll find lots of information posted by others.

Mike
 

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boomerang opeler
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you folks do realise this is a 3 year old post dont you and if you click on Lasse H's posts you will see hes sorted it :)
 

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The irmshers do fit with minor modifications, anything longer requires more work. try a search to see more details.
 

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Dual downdrafts would be a chore on a 1.9 and keep it under the hood. Side drafts are easy to tune and synchronize. Dean got it right off with no prior experience. He got the Irmshers to fit without removing any metal so it can be done. My Magnoletsi with twins still has a better heating system than stock so it depends a lot on what your trying for and willing to undertake.
 
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