I finally found a book detailing how to tune the Dellorto on my '76 Spit
(How to build and power tune Weber & Dellorto DCOE & DHLA Carburetors,
Des Hammill, Veloce Publishing. Found it at BarnesandNoble.com). With
this new found wealth of knowledge in hand (at least enough to be
dangerous) I tried my hand at it yesterday evening.
First the specs: this is a '76 Spit, Dellorto DHLA 45, open exhaust, '75
block - pistons, stock cam, electronic ignition.
I found that the motor idled best at 22 btdc at 1k rpm. The timing was
initially set for about 14 btdc. Moving up to 22 jumped the idle rpms
way up, and required a couple on turns on the idle screw to bring it
back down to 1k.
With the timing in place and the idle set, the motor seemed to be
running rich. Each mixture screw was adjusted in 1/4 turn at a time
until the idle smoothed out and motor "jumped" at the throttle. I ended
up leaning it out 1 1/4 turns.
The motor is alittle harder to crack with the advanced timing, but the
starter seems up to the task.
These new settings have not been road tested yet. It's a raining day
here in Northern Ohio.
Does this sound right? 22btdc seems high. Could there be a problem
somewhere else that is causing this? or is it just a sloppy distributor
and/or "calibration error".
John Schroth
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