Carbureted LSX forum - Question for guys running a 750 holley
06-02-2012, 01:36 PM
Hey what's size jets are you guys running in your Holley 750's? I have dual inlet single accel pump.
Pop N Wood
06-02-2012, 05:43 PM
71 front and 74 secondary
06-02-2012, 08:22 PM
Check the stickys, tons of info there.
06-02-2012, 10:38 PM
Now I'm a rookie when it comes to carbs but will there be secondary jets or just metering block (or both!) because like I said its dual inlet but only single accel pump?
Also on the power valve...is there different sizes? Everyone I've ever talked to says they eliminate them all together. I imagine it's on there for a reason...
Also if it helps the carb I have is a 3310(4160) 750 off a 375/396 chevelle...
Pop N Wood
06-03-2012, 08:40 AM
Holley lists the stock configuration of there different models on line
According to the sales stuff most 4160 "carbs feature vacuum secondaries with a metering plate that has no jets, power valves, or accelerator pumps. "
You don't need an accel pump with vacuum secondaries. The vac mechanism is suppose to open slowly enough to not need that.
Power valves are rated by what vac pressure they start to open. The actual flow through them is regulated by a power valve channel restrictor (PVCR). This is a press in restrictor in the metering block itself right behind the power valve. With a 4160 it is probably not adjustable.
You want to run a power valve on the street if you expect any type of decent gas mileage when cruising. What is does is allows you to run smaller jets so you have a lean air-fuel mixture when cruising. When you hit the gas, the manifold vacuum drops opening the power valve and enriching the fuel mixture for WOT. You don't need a power valve in the secondaries cause most cars won't have those open when cruising.
If you block off the power valve in the primaries, then you need to put in significantly larger jets in the primaries. You will then need to tune them so you are running rich all the time. Most people would consider that a race set up. You have the wrong carb for that.
06-04-2012, 02:06 PM
Ok cool thanks for the info I appreciate it...I'm going to rebuild it and prob use the stock jets/metering block and see where I'm at...I've been looking for a cheap Wideband to tune it in.
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