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Carb Upgrade, Got lots of Questions

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Old 05-25-10, 12:15 AM
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Fighting Global Cooling

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Carb Upgrade, Got lots of Questions

So my stock carb took a carp and needs a build but i figured why bother building it when i can go aftermarket! So I got my hands on a Dellorto DHLA 40 and an intake so far. I've got the rebuild kit for it, new trumpets, new filter assembly, linkage set up, and I've got a fuel pressure regulator at the shop waiting.

Now for the questions. First, what jet sizes should I order? What venturi size should I go with? and what should I set the fuel pressure at? Other than that I think I'm well on my way towards getting the car back on the road, with added power!
Old 05-25-10, 07:03 AM
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Waffles - hmmm good

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A DHLA 40? Really? Or is that a typo? Sure its not a DHLA 48 prepped by RB. If not
the tuning phase will be more difficult.

If its really a 40 you may not need much smaller venturis. My 48 runs 36
venturis on my stockport 12A. Fuel pressure must be between 2 and 2.5 psi.
No more or it will over power the needle/seat and always run rich. Not sure
for a 40 what the jets should be. Take a look at the site http://www.gruntled.com/Dellorto
for details on RB prepped Dells and tuning.
Old 05-30-10, 03:50 PM
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Alright got my jets and everything figured out, but now I have a new question, regardsing OMP Delete.

So since this carb doesnt have OMP injection, I'm going to have to run premix. First questions is:

What all goes in to the OMP delete? I got the block off plate from mazdatrix so is all I have to do is remove the omp and lines and bolt on the block off plate? If so will my oil pressure remain the same? Also, premix ratio is 1oz/gal right?
Old 05-30-10, 04:43 PM
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yes remove the omp and bolt on the plate. that pump, weather on it or not, has no control over the oil pressure.
Old 05-30-10, 07:39 PM
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Ok I wasnt sure if it acted as a sort of relief point or something, thanks. I suppose its not really an oil circuit as it is anyways.
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