Proper Tuning / Building part 2........

To expand on the last post-there's a lot of  "hidden" power in your car that people lose because of bad tuning or simple neglect. And when guys do modify their cars, they often buy or build the wrong combination, which sometimes results in a car that doesn't run as good as it did stock. Here's some tips to avoid these problems. # 1. Exhaust. Like I said in the earlier  post-I see so many cars with $5000 paint jobs and $2000 worth of tires and wheels, and the exhaust system is crushed, rusted out, or leaking. Even if your running stock exhaust manifolds a good, free flowing dual exhaust system can add 30 or 40 hp. If your car is a 1975 and later model and you live in a state that has smog inspections that check for equipment, don't despair. The law says you can't REMOVE the catalytic converter, it doesn't say you can't ADD one. This is how the Mecham brothers slipped the "Macho T/A's" through. Research has shown that the bottleneck is not the converter itself, but the fact that the exhaust goes into a single pipe before going into the converter. This why modern high performance cars like the Mustang GT, Camaro SS, Hemi Chargers and Challengers, and Corvettes have two converters- one on each side. And no one will say these cars don't run. Summitt Racing sells EPA legal, high flow catalytic conveters, so you could build a legal, free breathing system for your '78 Z/28 or '85 Monte Carlo SS or whatever relatively cheap. # 2. Carburation / Induction.  A lot of people don't realize that if you install headers and dual exhausts, ( or just duals ) Your carb will more than likely ( unless it was over-rich to begin with ) be too lean. Some electronic carbs i.e-L69 Camaros and Firebirds, pre-'87 "5.0" Mustangs-will automatically adjust to minor changes like this, and the car will run fine. However, if you have an old-school-i.e. non electronically controlled carb you'll probably have to re-jet the carb a little richer to compensate for the freer-breathing exhaust. Here's another area where people screw up. An aftermarket intake and properly jetted carb can add as much as 50 hp, if it's the right setup. I've seen guys put a single-plane Edelbrock Victor Jr. and a 750 Double-Pumper Holley on an other wise stock '72 Camaro with a stock 8.5:1 compression  L48 350, an automatic, and 3.08 gears, and then wonder why it doesn't run as good it did stock. After all ( Insert magazine name here-Hot Rod, Car Craft, Popular Hot Rodding etc ) said the Victor Jr / 750 Double-Pumper combo made the most power on a dyno test. They forgot that the test engine was an 11:1 compression 383 stroker with a .500 lift cam, and aftermarket aluminum heads, and it was going in a car with a 3 grand converter and 4.11 gears!! A Victor Jr. is basically a Nascar manifold designed to make maximum power between 3,500-8,000 rpm, and probably LOST 25-30 lbs of torque below 3 grand compared to the stock intake! Not something you'd put on a mild street car. The guy would have been way better off using an Edelbrock Performer that's designed to make power from idle-5,500 rpm, and re-jetting his Quadrajet, or using a vacuum-secondary 600 cfm Holley or Edelbrock carb. The bottom line is it's pretty hard to out-perform a dual-plane manifold and a vacuum-secondary carb on the street. I said this to a friend back in the 1990's when "Pro Street" was all the rage-"If a Super Stock Firebird can run 11.30s with a Quadrajet on an iron manifold, why do you need a tunnel-ram and dual 660 Holleys?"  A single-plane manifold and a double-pumper would be good on a light, stiffly geared car with a stick where you could pop the clutch at 3,500-4,000 rpm.  Especially if you have an automatic transmission ( which means you can't rev the engine at the line / stoplight to clean it out ) you need a carb that comes off the line cleanly with no bog. The twin accelerator pumps and mechanical secondarys open on a Double-Pumper if you even look at the throttle, and it dumps gas down the engine's throat like flushing a toilet. An AVS-type carb where you can adjust when the secondarys open are much better for a car with an automatic, a stock converter and high ( low numeric ) gearing. # 3. "We shall overcam" seems to be the amateur hot-rodder's mantra. Unless you have a four-speed and 3.73:1 or stiffer gearing, it's better to err on the side of caution when choosing a cam. I had a customer that was kind of a do-it yourself mechanic. He wanted more power for his 350 Suburban that he towed his boat with. I told him to buy some 1 5/8 inch headers, and to get an Edelbrock Performer intake and matching cam. I told him this package would give him a big improvement in low and mid-range torque-which is what you need for towing. He goes and listens to the idiot working the counter at AutoZone, who sells him the Performer "RPM" package and  headers. He spent the whole weekend installing these parts, and then griped at me that the truck wouldn't idle and  he had no power brakes, and it didn't run as good as it did stock!!  I informed him ( and showed him the charts in the Edelbrock catalog ) that the reason the truck wouldn't idle and ran like crap at low speed is the "RPM" cam has 234 / 244 duration ( at .050 lift ) and .488 / 510 lift, and only makes 10 inches of vacuum at 1000 rpm!!  For a reference point this cam has MORE lift and duration than the Vaunted Pontiac Ram Air IV cam and the Olds "W30" cam, both of which were designed for engines 400 or 455 cubes, and were only available with 3.90:1 or 4.33:1 gears in a GTO or a 442!! This cam has more lift and duration than the solid-lifter cam in an LS6 454 Chevelle!!  Definitely not a cam you'd put in a small-block work truck. I showed him the "regular" Performer cam had 204 / 214 duration ( at .050 ) and .420 / .442 lift, and had 15 inches of vacuum at idle. This would have given him the improvement in low-end and mid-range torque he was looking for, and operated his power accesories easily. I traded him a Performer manifold I had laying around for the "RPM" manifold ( I'm always looking for Chevy and Pontiac parts, and have friends that are too ) and since he'd installed it, he had to eat the cam. But after he bought and installed the milder cam and intake he agreed-the truck had way more power and actually got better gas mileage-16 mpg instead of 12. I asked him-"Didn't you read the box where it says "Designed for high performance vehicles only." "Not recommended for vehicles over 3,600 lbs, or for towing applications?" "But the guy at Autozone said--" he started-and I cut him off.  "The 10 dollar an hour idiot at Autozone knows more than I do, and more than Vic Edelbrock and his team of  engineers?"  He had to laugh. "When you put it that way, it does sound crazy." "I should have listened to you, or at least read the Edelbrock catalog for their recommendations."  You think?  Anyway-most cam manufacturer's-Lunati, Crane, Competition Cams, etc-will give you good advice in their catalogs on what cam works best with a certain engine size, carb and intake, compression, and whether or not it will work with a stock torque converter. If you follow these guidelines-not the advice of some self-proclaimed "expert" whose never raced a car or built an engine in his life, you'll be very happy with your car's performance. Mastermind