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2.2 litre engine running on 2 litre carbs

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I have rebuilt my 2 litre engine as a 2.2 Litre using the original 2 litre carbs. There is much more low down torque and the driving experience is much better. My question is this, is there a dramatic further improvement by swapping the carbs. I could try and buy a pair of 2.2 carbs and rebuild them or fit all the jets, venturies and so on to mine, either way this is expensive, so is it worth it?

Peter

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Morning Peter

I agree with David.

But if you want something to while away the winter months..

Rather than going out to buy a set of 2.2 carbs, (which may only have bigger jets)  why not strip down, clean and re-furbish the ones you have (if not already done).  I learnt a lot about mine when I did them  

It cost me around £150 to do, but they had been off the road for 26 yrs.   Just remember that when you put them back on they will need setting up again.

Roland

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You learn something new every day

I was not aware that there was a difference between carbs fitted to the 907 engine and those fitted to the 912HC engine.

Is there much of a drawback to fitting 907 carbs?

Thanks

Brian 

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ISTR that the earliest 907 carbs actually have the biggest venturis, so it's only a matter of jetting for the extra airflow.  Although my restoration project was undrivable when I bought it it had been changed to a 2.2 like yours and was on the original carbs as far as I know.  Not sure if the jets had been changed though.

Pete

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I had a conversation with Mike Taylor at Lotusbits about this, he showed me some 2.2 bodies and pointed out some special drillings in the carb body casting. As he had a lot of interest in 2.2 carbs he set about developing jets and venturies to convert 2l carbs to the same spec. The parts when bought new were quite expensive so I am wondering if it is all worth doing.

Peter

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Very slight improvement, if any whatsoever, in shifting over to carbs for the 2.2 as they were much the same animal as fitted originally. You've likely achieved the single greatest bump in engine performance via that change in going 2.2, further gains without substantial re-work will be in terms of minor driveability via tuning. The better low range breathing of the 2.2 actually improves behaviour of the carbs by bringing circuits in more quickly. Next best upgrade may be to install distributor-less ignition system for benefit of optimal spark advance curve, though quite a further outlay to accomplish.

Cheers   

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