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914World.com _ 914World Garage _ Need help from Carb guys

Posted by: ahdoman Dec 8 2006, 03:14 PM

I've got Dellorto 36's. Anybody know what the relationship is between the bypass screw and the mixture screw? How about base settings? To begin sync?

Posted by: jr91472 Dec 8 2006, 04:33 PM

Like Webers, Dellorto has a Tech Book that you can get at Amazon or CB Performance. If I can find mine, I will see if the offer and baseline specs.

The mixture is just that, it controls the air/fuel ratio, one per barrel / cylinder.

The bypass screw IIRC is to fine tune the sync (i.e air flow) between the two barrels on the carb. I am pretty sure that the Tech Book doesn't really encourage you to mess with that.

The idea is that the idle screw on the carb controls the idle for both barrels. But in some cases, the individual barrels will not have the same air flow. I assume you have a Synchrometer (if not, get one). If that is the case (and it was with ONE of my Dell 40s) you use the air bypass screw to equalize the two barrels. That way when you adjust your idle screw, both barrels will be in sycn with each other.

I strongly recommend you get the Dellorto Tech Book.

good luck.

Posted by: jr91472 Dec 8 2006, 04:45 PM

The Tech Book is by Bob Tomlinson. I got mine from CB Performance.

For a starting point, it recommends (for DRLAs) that mixture screws be opened 3 full turns from closed. Bypass screws should be fully closed and only adjusted as I stated above.

Also, just so you know what you have. The factory default values for Dell 36s are:

Vents 30
Airs 180
Mains 122
Idle 60
Accel Pump 50

Assuming you got them used, its good to know if someone replaced / monkeyed with them.

have fun.....

Posted by: Joe Sharp Dec 8 2006, 05:21 PM

Audioman: If your car is running bring it down this weekend and I show you how to set them up.
:PERMAGRIN: Joe

Posted by: Aaron Cox Dec 8 2006, 05:26 PM

Im with JR - leave em all closed and use them to make up for the difference between the 2 barrels on the carb....

CB weber book suggested .5 turn open.... so you have adjustment in both directions.... tried this and i was having velocity issues...

closed them all and runs bitchin

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