Inlet Manifold Holes?

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Phill2

Phill2

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Hi Guys


I'm just wondering what the small holes in the carb and manifold are for.


The stock manifold has 2 - one top and one bottom but the DDM billet manifold and gasket only have one.


Thanks


Phill
 
Great post!! Thanks. One of the photos shows a close up of the carbs bore -butterfly valve- showing the low speed hole in the bore of the carb that feeds gas. Walbro makes a butterfly valve that has a small notch that straddles this low speed hole. It provides an increase in the amount of air over the hole. pulls more fuel out of the hole. Tru trial and many errors, I have increased the size and shape of this notch on the butterfly hole. Once the "happy spot" on the butterfly notch has been reached- acheved, there is quite a large increase for the better in the way the Walbro Wt series carbs perform- 668-771-813-990- It allows a tuner to lean out the low speed fuel screw to a higher rpm -leaner setting and have no bog in the engine when the throttle is pulled wide open suddenly. Its easy to do. You just need a high quality phillips screwdriver- red lok-tite, and really small hobby files. As the size of the butterfly notch is increased, the car will run richer on the low speed fuel screw- and to a smaller extent - somewhat richer on the high speed fuel screw.- you have to lean it out- in baby steps - little bit at a time as you learn the carbs new flow rates. Many ultra lite aircraft guys do this mod for a smooth reliable idle and not have a lean out condition-
 
Here is an example of the butterfly mod. This is a WT-990, 1" velocity stack. You can see the mod to the right of the high speed check valve-the round brass part in the carbs bore. The photo says its a 813. its actually a 990.
 
You're right

Being new to 1/5 scale so I'd be lost without it

We sure do get a lot of technology and parts for $30 when we buy a carby
 
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