im not real familiar with the holley design inside the carbs, but any way to mechanically plug the jets or metering circuits with a solenoid or something like that to stop the flow untill you trigger the system on to run on meth?

 

I don't believe so, which brings up another good point. Unless the carb bowls were empty, vacuum would pull fuel through the boosters. So operating on fuel injection out of boost wouldn't be possible.

Does anyone know off hand the max percentage of fuel that can be supplied via the power valve on a typical boost referenced Holley 4bbl carb? I'd think tapping into this would be the easiest way to net a massive fuel percentage change.

The blow-thru carb guys are into the 'crutch' systems. These use an external pressure source (usually a 12V air pump turned on in boost) to open the power valve for boost enrichment. Then cruising/idle is done on 'smallish' jets. If there was a way to isolate the PV circuit and supply it with methanol (or race gas) I'd think it would work very well.

 

If the poster was running off of the fuel injection in a "Normal Mode" then the secondary carbs or secondary side of a 4 bbl would not need a Idle circuit, a transfer circuit, or a Power Valve circuit.
Only a Main Circuit would be required. So you could basically plug all of those circuits and you would have NO GAS FLOW thru the carb unless the MAIN CIRCUIT was functioning
which would be when the throttle blades were open and booster signal energized the circuit.

So the end carb bowls (or secondary bowl) would not be empty, the Fuel pump would keep them full of fuel thru the needles and seats.

The Primary side of the carb would be a simple air valve for the fuel injection side.

Tom V.

 

^ he so smart, that would be slick as shit

 

With an open plenum intake, the air/fuel is going in all directions unless you have a big spacer on top which adds volume and kills some of the runner signal when it hits the plenum. So how much difference there would be with any given runner ingestion of gas and methanol is hard to say. Some have proposed a injection set-up for the methanol and a NOS Spray bar deal would work for methanol too. Lots of cheap spray bar systems out there and solenoids to feed methanol fuel.

Then you could leave the carb on gas in both fuel bowls.

Tom V.

 

But in a mechanical spray bar set up is there any simple cheap way to control flow vs load