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Hib Halverson's Big Block From Hell Series

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Hib Halverson's Big Block From Hell Series

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by Hib Halverson
© December 2012

Information and Tools

From here on, it's DIY, but don't start without an understanding of carburetion theory and function along with in-depth knowledge of Holley 4150 fuel metering systems. If you're a rookie carb tuner, read: Super Tuning and Modifying Holley Carburetors, (PN SA08) from CarTech Books, along with Holley 4150 & 4160 Selection, Tuning and Repair (PN 36-133), Holley Tech (PN 36-27S) and the Holley Performance Catalog (PN L30924), all available from Holley. Information is on the Internet, too. One source is Holley's streaming video site, www.holleytv.com. If you're good with Google, you'll find more. Finally, make friends with a Holley retailer, such as the Carb Shop, because you'll need jets, power valves, accelerator pump cams and shooters, gaskets, a rebuild kit or other parts.

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Image:  Author

You can buy a fancy carb stands or you can make your own with a couple of bucks worth of 5/16-in bolts, nuts and washers.
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Image:  Author

If you're going to work on Holleys, you need a Jet Tool. It's a special tool designed to tighten and loosen jets without damaging them. Use one of these and your jets will love you.
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Image:  Holley Performance Products

If you're a serious carb tuner, you need a bunch of these. They are available in individual pairs or in jet "kits". You can get them from Holley retailers, such as the Carb Shop.

You need some special tools. A Holley Jet Tool (PN 26-68) prevents damage to jets during installation or removal. A vacuum gauge is needed to set idle mixtures and select power valves. Tweezers or forceps are great for handing tiny parts. Very small drills, from #80 (.0135") to #40 (.098"), may be necessary. You can't use a drill motor with these tiny bits, so get a "pin vise", a hand-operated tool for drilling small holes in soft metal.

Accurate measurement of air-fuel ratio (AFR) is required. It's done with an oxygen sensor (O2S) screwed into the exhaust. Inexpensive "rich-lean" indicators, which use narrow-band sensors are inadequate. A modern, wide-band oxygen sensor is required. I installed the Auto Meter "SportComp Wideband Air-Fuel Ratio Monitor" (PN 3378) which I picked because: 1) The Big Block from Hell already had SportComp instrumentation and my experience with it has been good. 2) It uses a Bosch wide-band O2S with a resolution of 0.1 air-fuel ratio and 3) I like its combination of a numeric display (reads AFR or lambda) and a "pseudo-analog" display of colored LEDs. Fine tuning a Double-Pumper's drivability is very difficult without a wide-band O2S like the Auto Meter.

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Image:  Holley Performance Products

This was the most important tool we used in this two-part series: the Auto Meter "Wide-Band Air Fuel Ratio Monitor". We mounted it on the car's steering column. This was what we saw during some of testing of the car's highway gas mileage. We're just on the rich side of stoichiometric.
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Image:  Author

The Auto Meter wide-band O2S comes with everything you need for installation—Bosch sensor, sensor bung, wiring harness and instructions. All you need to do is have the sensor bung welded in to your exhaust. We had ours put just downstream of the passenger side header collector.

Before you begin, make sure your ignition system is in good condition. If there are problems with ignition, address them before getting into carb tuning. More on ignition is in a sidebar to this article.

Lastly, you'll spend a fair amount of money on road testing. We burned hundreds of bucks worth of fuel in validating our drivability mods. You can, also, do the part-throttle work on a chassis dyno provided it's a "brake dyno" which can allow the car to run at part-throttle at constant speeds. Problem is, that could cost as much or more because dyno time can be pricey. Anyway you cut it, be it parts or testing; good carb tuning ain't cheap.

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