Who here runs twin dellorto's?

Looking for jetting figures and some info or even pictures of the accelerator pump rod settings. Engine is a stock 1400 (pretty sure).

Rebuilding a set now and need this info to help set them up as best I can before they get sent off again.

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email sent Chris, hope it helps..

stock 1400 didn't come with Dellorto carburetors. The stock 1200 SSS did, but that's an A12.




Dellorto

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It fits like this, and there is only one setting, the adjuster nut (73) can be fixed anywhere, then tighten the lock nut (74).

I would guess it should be set for zero lash at idle???

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Hmmm yeah not sure, these (the pump rod settings) will be crucial in getting the engine to run right, I don't want to send the carbs having been freshly rebuilt and then find that they aren't running right only because the accel pump settings were out.

Hey Deano, no email yet.

I ran the pump rods at only about 1mm lift (maybe less) on my last Mikuni carburetors, and that was running on a fairly heavily worked A12, perhaps these are the same.

Surprisingly dellorto's offer a combination of the Weber and Mikuni format, which in my opinion makes them the best carburetor of the lot. I'd need to see how easy they are to set up before I made my mind up but at the moment all the things I liked about Weber and Mikuni are featured all in the dellorto carb. Interesting stuff.

email got bounced for too large so have just tried again..

The pump settings for a DHLA are based on cc's expressed and because the there are different diaphragms, pump jets and an adjustable pump rod you can set it nearly anywhere.

- Accelerator pump
Adjust the accelerator pump injection quantity by fitting the carburettor to the special support with the proper gasket and connect the carburettor to a reservoir so that it is continuously supplied with fuel.
Put the two graduated measuring tubes, each having a capacity of 10 cc, under the drain pipes on the support in order to collect all the fuel pumped out. Open and close the throttle completely 20 times, with a few seconds’ break in between each time, and check that the amount of fuel collected in the tubes corresponds with the correct specification and is the same for both barrels. It not, adjust the pump delivery by resetting the nut and locknut fitted on the pump operating rod; remember that screwing the nuts up increases fuel delivery and vice versa. It there is any difference in volume between the two barrels, remove the pump jets and blow through them vigorously to correct this. Recheck until the correct setting is obtained and then ensure that the nut and locknut are retightened.

Okay cool so dellorto have got themselves some sort of a chart that corresponds with engine capacity and accel pump expressed cc's? Not a bad idea really.

Yeah okay, I'm not too keen on setting it anywhere, as I'm a bit skeptical to do so. I have the jet sizes here but really don't want to have to put fuel through them especially after the rebuild.

I'll try get a hold of a manual and have a read up on that too. Mikuni for example had a short write up with some approximate settings for the pump rod. Although those settings were fairly broad for the little A12 they were good enough to get the thing driving.

With accelator pumps in general, there are two factors:
1. Time of delivery. Perhaps a one second delivery is a good starting place.
2. Volume of delivery

There is both a pump jet and the rod/spring nut adjustment.

Pump jets for DHLA go from size 33 to 60. The size needed is not necessarily tied to the engine displacment but more on factors such as load and cam timing specs.

The pump jet is what sets the duration of the accel pump event.
The pump rod adjustment is what sets the amount of fuel delivered.

All of the above are also dependant on the rest of your jetting such as idle, idle progression and main circuits.