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How do you tune 40doce webers side drafts with wideband?


fast2002

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Well, ultimately, you strap the thing to a dyno,

and then find both maximum horsepower AND then

efficiency, and then tune to a nice, drivable compromise somewhere in the middle.

But that's expensive. What I do is use the wbo2 to see what's going on

at different rpm's, load ranges and throttle positions.

When I'm driving hard, I usually target 12.5- 12.8:1 for power- you can go

richer, but I've never seen any real hp gains, and the plugs read rich below

12.5.

Now it gets trickier- I use it at cruise and 'round town just to make sure

the mixture's in the ballpark. It takes a bit of jetting to get them to

behave at low throttle openings, but they'll do it.

The best use I've found is for finding problems- for example, if it stutters, what's

the mixture doing? If it bogs, likewise...

You really need a book on the Webers, because there are a LOT of jetting

changes you can make to the progression and idle circuits- the wbo2 will

just confirm the effects of the changes. The books (Pat Braden is good, Haynes

is OK) detail the workings of the different circuits- and pictures are invaluable.

And start with the venturis (chokes)- if they're not right, (i.e. 32mm or smaller)

getting drivability around town will be harder. And any choke change causes

a complete change in all the other jetting ranges...

hth,

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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