My goal here is a fun, streetable musclecar with a little kick-in-the-pants horsepower. I am also planning on bolting it to a TH350 trans and adding a 2,000-stall converter. I know it's a lot of questions, but I'm just trying to check all my options before laying down the money.MattVia e-mail
A The Xtreme Energy 268 is a great all-around street camshaft. It will give you decent idle quality and slow-speed performance and run very well to 5,500 rpm in your 383. When Comp designed this line of camshafts, the Xtreme in the name refers to pushing the rates of valvetrain acceleration to its extreme. That said, we've run both XE268 and XE274 camshafts through one of our dyno small-blocks. When we switched to 1.6 rockers from the production 1.5 ratio, we saw the limiting speed of the valvetrain come down approximately 500 rpm. When we found this, we increased the valvespring pressure and realized no increase in rpm over the lower spring pressures. This leads me to believe that Comp has done a great job in maxing out the valve motion rates with the 1.5 ratio rocker. When you throw more rocker ratio at the valve, you drive right past the stability limits. We would stick with the recommended valvetrain package that Comp Cams has designed to work with the XE268 camshaft. We think that you will be very happy with that package.
Rounding out your engine, we would go with the 750-cfm carb to run on your Performer RPM manifold. You're rarely at the top rpm range that the 800-cfm carb would be a benefit. The 750-cfm carb will give you better drivability and fuel economy. Good luck with your Nova.
It's All About E85Q There has been a real craze for this E85 fuel in the last year. In my state, Indiana, there are several plants producing this alcohol from grain, and several new plants under construction. Is this fuel 85 percent alcohol and 15 gas, or 85 percent gas and 15 alcohol? If this mixture is 15 percent alcohol and 85 gas there is not a problem, but if it is the other way around, how are the older cars going to run on this fuel? Also, my experience with 100-percent alcohol engines, like a 13:1 alcohol-modified engine, is that they will rust because the alcohol dries up all the oil, and you have to change it weekly, because the oil gets nasty. And if you run a carburetor, you have to drain the bowls down and fill them with gas and pump the gas through the carb, or else it will rust! What is going to prevent all of these problems if this fuel is 85 percent alcohol?David HayesVia e-mail
A Well, you have covered some the problems associated with running E85 in our earlier carbureted engines. We've talked about this subject several times and the questions keep coming in hot and heavy. Let's take a look at some other facts.
E85 is a mix of ethanol and gasoline. The blend is 85 percent ethanol and 15 percent gasoline. As you stated above, this mixture is problematic because of corrosion-because alcohol and ethanol love water. Water mixes easily with alcohol, and alcohol evaporates easily, leaving behind the moisture it was carrying. This is where the rust comes from. With late-model EFI-equipped flex-fuel vehicles this isn't much of a problem because the fuel system is a closed system. The fuel tanks are closed to atmospheric conditions, and the engine pulls a slight vacuum on the tank. The high-pressure side of the EFI is never introduced to free air until the fuel is injected into the port. This controls the problems with the fuel evaporating. With a standard carbureted system, you can see where the problems lie. Yes, the E85 would evaporate, and you could run additives to help limit the corrosion problems.