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Old 12-20-2017, 11:40 PM   #1 (permalink)
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Questions about modifying venturis for better... everything? (Weber DGV)

So a friend of mine is about to re-install an old (but rebuilt) 1.6 Kent motor into his MK1 Cortina. I'm not sure on the specs, but it has a 2-barrel manifold and he's looking at upgrading from the 32/36 DGV he had previously, to a 38DGMS, so he probably has more than 100hp.

The 32/36 represents the primary and secondary throttle diameter (in mm), and it has 26/27mm main venturis respectively.

I was wondering what can be done to increase airflow without changing to a different carb type, as the 38DGMS opens both throats simultaneously, so he will most likely lose drivability.

Looking at the carb, it appears that the support legs for the boosters can be streamlined somewhat, and the boosters can be knife-edged. The booster design itself is... poor. Can they be internally modified to increase flow *and* increase or maintain vacuum signal?

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Old 12-21-2017, 03:41 AM   #2 (permalink)
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32/36 is what is called for on my '87 Ram D-50 2.6 for the Webber conversation , 105hp. Without supporting modds ; intske , cam , header,and exhaust the larger carbs are just toomuch carb. So I've read.
Throw a vacuum gage on it .1-3" at wide open mid to red line and the carb is the point of restriction, and bigger is warnted. 0"of vac means just right or too big. Over size is only good at top end and compromises mid and bottom rpm.
My boss from years ago had a pair 42mm's on his 69VW bug . Poor thing would pull the front tires off the ground, catching second gear. He had to delete the viscosity stacks to get the carbs to fit under the hood with only a 3"offset. When he did he had to rejet to compinsate for less/ more turbulent air entering the carb.

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