Holley Emulsion Bleeds

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mopowers

mopowers

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I've been tuning my 650 Proform DP and noticed these open threaded holes. I believe these are emulsion bleeds, but correct me if I'm wrong. Should these have restrictors in them??? What exactly do these do?

Thanks!
 
Forgot the picture...

Picture0226171709_1.jpg
 
It depends.

It depends on what size the tiny holes are in the block.

I would block the middle hole, and use a .026-.028 hole in the top and bottom if they are not that size already. If they are, just plug the middle hole.
 
yellow rose said:
It depends.

It depends on what size the tiny holes are in the block.

I would block the middle hole, and use a .026-.028 hole in the top and bottom if they are not that size already. If they are, just plug the middle hole.
Click to expand...

Thanks for the input. What exactly do they do?
 
They add air to the fuel before it leaves the booster. And it gets more complicated from there. More emulsion isn't always better.
 
Agreed, block the middle one if it is drilled. They are all likely a .026-.028 hole as mentioned.

Unfortunately, the emulsion approach has gone the way of a sort of monkey see, monkey do mindset. One manufacturer puts 5+ active emulsions in the metering blocks and others think, hey, those guys did it so we should as well. It's a worm hole and not always beneficial.

In many of those 5 emulsion blocks, I block # 1, 3 and 5 leaving 2 & 4 open. Similar to the older 750-780VS metering block approach which was a really solid metering block. Many times that cleans up a bunch of mid range and cruise issues when on the main circuit.
 
So, you guys are right. There are tiny holes in the block itself. Didn't pull out my pin gauges, but I'd say they're about .026-.028". I called a distributor of Proform carbs and they said those threaded emulsion holes come open from the factory with the previously mentioned .028" hole below them. Why is it advised to block the middle hole?
 
If Thumper (Dom) is willing to help you with a base tune on your carb, take him up. Might shorten the amount of time you need to fidget with the thing.
 
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