A good-flowing dual-exhaust...
A good-flowing dual-exhaust system should always be the first step when performance-building a car.
Budget-Crisis Buildup
Chris E., via CarCraft.com: I really enjoy your magazine. I look forward to every new issue, and all your tech articles are awesome. I have a '74 Nova and my girlfriend's dad and I are going to yank the motor and trans because of oil and transmission leaks. I figure while I have the motor out I will try to pull a little more power from it. The car has the original 350, which is probably a two-bolt-main motor. The only upgrades are an Offenhauser intake manifold and a 600-cfm Carter AFB. I rebuilt the carb, so it works beautifully, and the motor runs awesome, but it doesn't have the power I want. I'm looking to pull about 350 hp (the more power, the better) since I'm still in high school, but I want it to be a simple build and be reliable since it is my first old car and my first build. I was thinking about building a 383, but that would include getting a whole new rotating assembly. I also was thinking that the heads could be upgraded. I want to reuse as many of the parts as I can. Any advice would be greatly appreciated
Jeff Smith: In a time not all that long ago, I remember being a car-crafter with no money. The reason your girlfriend's dad is helping you is probably so you won't leak oil all over his driveway every time you visit! I have some ideas that are budget-conscious and will help with power. Regardless of what other modifications you can afford, a true dual-exhaust system must be your first consideration. You didn't mention what exhaust system is on the car right now. If there already is dual exhaust, make sure it's at least a 211/44-inch pair of lead-down pipes. If it's a single-exhaust system, this is where I would spend the money even if you did nothing else to the engine other than fix the leaks. For example, Flowmaster makes a system called American Thunder, which consists of 211/42-inch mandrel-bent lead-down pipes, and a cross-flow 80-series muffler that will mount in the stock location but offers excellent exhaust flow potential with dual inlet and outlets. This system is PN 17104, and sells through Summit Racing for $369.95. You'll love it 'cause it's kinda loud. Or, you can build a more typical dual-muffler, dual-exhaust system using affordable mufflers like a pair of DynoMax Super Turbo mufflers that are also available through Summit for under $40 each. If your car has single exhaust, just adding dual exhaust and a pair of mufflers will make a big difference not just in power, but will improve your fuel mileage as well.
As for the engine, do a compression test first to evaluate cylinder balance. If all cylinders read around 170 psi or more, then you don't need to rebuild the short-block to seal it up. But if this is a high-mileage engine with low cranking pressure of under 160 psi, then it would be a good idea to start by disassembling the engine, getting it as clean as you can, and installing new rings and bearings. Hit the cylinder walls with a bottlebrush-type hone to give the new rings something to seal against, then reassemble the short-block. Remember to number each main cap and connecting rod and cap so they don't get mixed-up.
A nice hydraulic camshaft would also help performance, and you can get a decent Crane, Comp Cams, or other flat-tappet hydraulic cam and lifters for around $200 plus the cost of some new gaskets. As an example, consider a Comp Cams Xtreme Energy XE256 cam (PN 12-230-2 for $103.95 from Summit Racing). This cam has 206/212 degrees of duration at 0.050-inch checking height and 0.432/0.444-inch lift figures. The lift and duration are very mild but this will add torque and a little horsepower to your small-block. You'll also need a new set of hydraulic lifters with that cam (PN 812-16, $69.95 from Summit Racing) and a new timing chain that will set you back about $30. You can probably reuse the original pushrods.
Next, if you can afford a set of heads, we'd suggest a pair of cast-iron replacements in order to keep from sending you into deficit spending. The magazines get so caught up in the horsepower wars that we often overlook the guy who can barely afford a new cam and lifters. The idea here is that these are direct-replacement heads with larger 2.02/1.60-inch valves and will probably flow better than your stock heads. We don't have any personal experience with these heads, but the price is sure righteous at $650 a pair, complete and ready to bolt on. It's PN 152123 from Summit Racing. For a little more money you could go with a set of Vortec heads that cost about the same, but they'll demand a different intake manifold, which will add another $165 to the price tag. With the Summit heads, you can reuse your old intake and carb.
A final suggestion would be to look into what it would cost to rebuild your stock heads. But do your homework, assuming you will have to buy new valves and springs. Realistically, by the time your machine shop has put in new guides, performed a valve job, and added the new parts, the price will be at least $650, making the new heads a much simpler way to go. More expensive, higher-flowing heads will make a big difference even in very mild applications, but only go there if you can afford it. Otherwise, the stock replacement heads will make decent power and not send you to the poorhouse. After all, once you get your car back together, you'll want to spend a little money on your girlfriend to treat her nice. That, Chris, will score big points with her dad. Tell him you want to treat his daughter the way she deserves-dads love that kind of stuff.
More Info
Summit Racing Equipment; Akron, OH; 800/230-3030, summitracing.com