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Mark Parker #863283 11/16/21 2:44 am
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We tried several welders and couldn't get one to do anything with the tunnel.

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Mark Parker #863298 11/16/21 9:50 am
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That makes me feel better about my attempt. It's awkward. A gun welder with a mig might get metal in there but it's not a good place. We can fit a plate. The engine will not know.

The dynamics of this stop starting flow to appreciate is that air is hitting 300+mph with 28" of vac but the motor can produce far more vac when the inlet is starting to open on overlap100-120" and that is getting it moving, at full lift it may have 20" and peak the port velocity, but that is a dynamic going on and effecting how the thing goes.

Last edited by Mark Parker; 11/16/21 10:16 am.

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Mark Parker #863301 11/16/21 10:57 am
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Speedway engines are limited to a maximum 34mm carb. For a 12,000 rpm 500cc cylinder that is a tiny carb.
To get the maximum flow the inlet port is very short, on my engines 85mm from the back if the valve to the step in the carb rubber where the carb seats, the carb is only 25mm to the 2mm thick flat slide, 64mm to the end of the 74mm diameter bellmouth


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