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tuning 45' dellorto's
tigertom - 25/2/09 at 11:14 AM

any of you guys know how to tune up twin 45' dellorto's.my Co readings are way down at .7% and pps reading is about 700.i've been told there not running rich enough.also plugs are sooting up very quickly.pictures on what screws on the carbs adjust the fuelling would be really great as the mechanic has not worked on these before.


Mr Whippy - 25/2/09 at 11:48 AM

sooting up of the plugs usually means its running too rich


coozer - 25/2/09 at 12:11 PM

Yeah, go on ebay and buy some bike carbs, fitting them will be easier and more cost efficient.


Paul TigerB6 - 25/2/09 at 12:32 PM

quote:
Originally posted by coozer
Yeah, go on ebay and buy some bike carbs, fitting them will be easier and more cost efficient.


Especially when 2nd hand Dellorto's with manifold sell for such a good price on fleabay etc. The other advantage with bike carbs is they stay in tune better than DHLA's and are simpler to set up.


flibble - 25/2/09 at 12:37 PM

Any use?
Linky


tigertom - 25/2/09 at 01:15 PM

thanks a lot flibble.that looks exactly wot i'm after.


Memphis Twin - 25/2/09 at 03:46 PM

quote:
Originally posted by Paul TigerB6
quote:
Originally posted by coozer
Yeah, go on ebay and buy some bike carbs, fitting them will be easier and more cost efficient.


Especially when 2nd hand Dellorto's with manifold sell for such a good price on fleabay etc. The other advantage with bike carbs is they stay in tune better than DHLA's and are simpler to set up.


What a load of horsesh*t.

Once set up correctly, Webers and Dellortos cannot go "out of tune" as everything is fixed. Fixed jets, emulsion tubes, chokes - the lot.

Bike carbs may appear inexpensive, but once you've got a Bogg Bros (or similar) manifold fabricated, and all the rubbers, jets and dyno time, then the cost is about the same as a pair of good used Webers and manifold. 45s go for about £300 a pair; 40s for about £200 max. A manifold can be found for £25. And remember, Webers and Dellortos give a much better throttle response than CV bike carbs...which is why after experimenting with bike carbs over 12 years ago on my hillclimb cars, I went back to big, gas guzzling Webers.

If you want to pootle around and have good fuel economy, I suggest that you've chosen the wrong type of car. Perhaps a Nissan Micra would be better....

And by the way, I've seen some absolutely apalling bike carb manifolds; full of sharp angles which do absolutely sod-all for airflow (except REDUCE it!).

[Edited on 25/2/09 by Memphis Twin]


cliftyhanger - 25/2/09 at 09:04 PM

^^^ has a fair point. The only thing that needs adjusting is the balance. And TBH the homemade linkages on bike carbs can leave a lot to be desired, but then again so can those on weber/dellorto. The balance is REALLY important, and often overlooked.
Anyways, enough on the thread drift

Bear in mind the idle jets on emmission carbs do not follow the "rules" My 1800 zetec ran 62 idle jets, lots larger than generally suggested but needed owing to the model of carb, so worth watching.
There is a DOS based program out on t'internet for calculating jettings too, drop me a pm with your email address and I can send it to you, along with some other weber/dellorto stuff.
Clive


flak monkey - 25/2/09 at 09:08 PM

quote:
Originally posted by Memphis Twin
quote:
Originally posted by Paul TigerB6
quote:
Originally posted by coozer
Yeah, go on ebay and buy some bike carbs, fitting them will be easier and more cost efficient.


Especially when 2nd hand Dellorto's with manifold sell for such a good price on fleabay etc. The other advantage with bike carbs is they stay in tune better than DHLA's and are simpler to set up.


What a load of horsesh*t.

Once set up correctly, Webers and Dellortos cannot go "out of tune" as everything is fixed. Fixed jets, emulsion tubes, chokes - the lot.

Bike carbs may appear inexpensive, but once you've got a Bogg Bros (or similar) manifold fabricated, and all the rubbers, jets and dyno time, then the cost is about the same as a pair of good used Webers and manifold. 45s go for about £300 a pair; 40s for about £200 max. A manifold can be found for £25. And remember, Webers and Dellortos give a much better throttle response than CV bike carbs...which is why after experimenting with bike carbs over 12 years ago on my hillclimb cars, I went back to big, gas guzzling Webers.

If you want to pootle around and have good fuel economy, I suggest that you've chosen the wrong type of car. Perhaps a Nissan Micra would be better....

And by the way, I've seen some absolutely apalling bike carb manifolds; full of sharp angles which do absolutely sod-all for airflow (except REDUCE it!).



Seconded....