Holley/Demon Carb stumble

Cudafever said

Found the thread with the metering blocks cutaway
Page 4
Power Valve Selection: The Definitive Answer

So i'm trying to get rid of the pore transaction with a smaller air bleed. Idle air bleed? just rears or all ?

I have a 6.5 Power Valve in and am thinking of going with a 10.5 that i have on hand.

So here is my question. do i plug the PV and find the flat spot?
Do i use vacuum gauge and set it just above my starting line launch rpm or do i watch the vacuum and put a power valve in just above whatever it stumbles at.???

Click to expand...

I’d start by measuring cruise vacuum. Then I’d check that against how much vacuum you pull at starting line RPM under load because you’re foot braking.

Don’t you have billet metering blocks? They won’t have porosity like those junkers (I didn’t look at the link you posted yet, but I suspect that it has pictures of a pair of metering blocks I cut away that Mattax was kind enough to post so everyone could see them...which is why I can call them junkers...because they are).

Any time you have a jet that meters air, going bigger will make the A/F ratio leaner. Any time you have a jet that meters fuel, going bigger will make the A/F ratio richer.

Which bleed you change makes a difference where the change will change the shape of the fuel curve. For example, if you change the main air bleed, you will make the fuel curve at WOT leaner, but you also delay the booster coming on. So if you want to lean out the end of the fuel curve, but you don’t want to delay the booster, you can change an emulsion jet to a larger one lower in the metering block.

Its stuff you have to test.