Hot Rod Build Budget: $1,000
Dang, a grand! Someone’s been saving their pennies. As a reward, let’s go racing. We admit, we’ve been a little conservative so far. Most folks would have already had you swapping intakes and camshafts, but we’ve established a sound engine baseline, a proper tune-up, and an upgraded exhaust system. You deserve some action now, so let’s talk about a better induction system. And nitrous.
If you’ve already rebuilt the carb, even a stock carb, and it is working properly, it’s smarter to spend your limited dollars on a better intake manifold. It’s all about maximizing what you have and what fits under your hood.
Before you buy that tall intake, be sure to measure the hood clearance or plan to cut a hole.
Remember that every new part has some costs above the component itself. Removing an old intake will require new intake and carb gaskets, and depending on if you’re switching around between FI and carb, it might also demand a fuel-pressure regulator.
Enough sensible stuff. Let’s assume we have a reliable 350ci stock engine with a mandrel-bent 2.5-inch dual exhaust system, headers, and a dual-plane intake with a 600 cfm Holley carburetor. The horsepower gods came down from Drag City, handed you $600, and told you that it had to be spent on your car immediately to make it go faster. The answer to that challenge can be found in one word: Nitrous.
There are several nitrous companies, but we’re partial to the NOS Cheater system. The base price we saw for this system online is $569.66. There are less expensive kits out there, but the Cheater kit offers the greatest opportunity for making more power with simple jetting changes; the less expensive kits will require buying additional parts to bump the power. It’s worth noting, however, the hidden costs of nitrous.
All kits are delivered with an empty bottle because of safety hazards of shipping pressurized containers. You have to fill that bottle at roughly $5.00 per pound. That 10-pound bottle just added $50. The next thing you will learn is how quickly you can empty that bottle. You might get three good quarter-mile runs out of a full 10-pound bottle.
Nitrous systems also rely on a source of reliable fuel pressure. A basic 100-hp system doesn’t place a great load on a typical fuel delivery system, but as we hit 150 to 200 hp, the tuner will need to ensure fuel pressure is stable. Tapping a line off a stock fuel pump feed line might not be sufficient to feed a 150-hp nitrous system. You’ll need to build a reliable fuel-delivery system to supply fuel and pressure to feed 600 hp.
A 350-hp naturally aspirated small-block engine with a 200-hp nitrous kit is making 550 hp, but if the fuel pressure falls off at the point of highest demand, that’s how melted pistons happen. If you can’t afford a quality fuel-delivery system, then you might want to wait on the cheater gas.
Just tuning your existing carb can make power. Stock vacuum secondary Holleys come with a stiff diaphragm spring that delays the secondary opening. A spring kit from Holley can change that. We’d also suggest this quick-change cover that allows you to change springs without having to remove the diaphragm housings from the carburetor. The spring kit PN is 20-13, and the quick-change lid is PN 20-59.
Making Q-jet secondary metering changes is stupid easy. The secondary metering rods are attached to this hanger. As the secondary air valve door opens, the hanger follows a cam that pulls the metering rods up out of their fixed jets. A thinner metering rod tip allows more fuel to pass through the fixed jets. The key is to tune for the best power with the right set of metering rods. These rods are available through JET Performance.
The 4160-style Holley uses a metering plate with fixed jets. Making a secondary jet change requires replacing the entire plate. A 4150-style Holley uses a secondary metering block (foreground) that uses jets that are simple to replace. Holley sells a 4160-to-4150 conversion kit (PN 34-6) complete with the gaskets and longer float bowl screws.