February 2011 Chevy High Performance Q&A

Luck, Where Preparation Meets Opportunity

Kevin McClelland Dec 30, 2011 0 Comment(s)
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Icing

I’ve read a few articles that make mention of icing problems when using an Edelbrock Air-Gap intake. I have no idea what that means. The person I bought my intake from said he cooked his engine because of icing. I asked if he was putting a bag of ice on the intake between runs and the answer was no, not that type of icing. Would you please explain? Thanks.

Michael Copp
Brighton, MI

Carburetor icing is just about a thing of the past. Back in the day, when our cars were all carbureted, it was a regular condition in very cold climates. Moisture in the air passing through the carburetor would freeze and the ice adhered to the throttle blades, due to the lack of heat in the intake air and to the manifold because of the elimination of the exhaust crossover in the Air-Gap-style manifolds. This crossover is removed to boost performance by lowering the inlet charge temperature. In the winter months, the cold air comes through the carburetor, and the velocity increases in the venturi boosters, drawing the atomized fuel into the airstream, which lowers the temperature of the air to the freezing point. The throttle blades are in the way of the airflow and the moisture is deposited on the blades in the form of ice. This can be very dangerous, causing the throttle blades to be held open and not return to idle. The ice can also plug idle transfer slots in the carburetor body, causing the engine vacuum to draw directly on the idle circuit of the car which causes the engine to run quite rich.

We’re not sure how the previous owner of your manifold blew his engine because of carburetor icing. We’ve only seen the engines go rich when this happens. When you go to wide-open throttle, the ice causes a small restriction to airflow and the fuel and air get to the engine. The only true remedy to carburetor icing is to introduce heat into the airstream of the engine. Our high-flow, open-element air cleaners that give us great performance feed the engine cold air. You could run some type of air cleaner housing in the winter to add exhaust system heat to the intake air. You can also try to add a lubricant to the fuel, which will coat the throttle blades with slippery stuff, preventing the ice buildup. A good top end lubricant, such as Marvel Mystery Oil, added to your fuel during the winter months can help, but will not prevent icing in very cold high-humidity conditions. It is much easier than rigging up some type of heated induction system. Good luck!

Which Intake/Carb for a 283?

I’m doing my first complete engine rebuild for a friend’s ’62 Impala two-door with a 283 that was purchased recently. He wanted to keep the 283 for the authenticity. This car will probably never hit the track, so a larger-displacement engine is not needed. However, that doesn’t mean we don’t want this 283 to be decent when stepping on the go-pedal. The block was stripped and sent to the machinist. After being inspected, the machinist informed us we could go 0.040-inch over on the pistons. My friend bought regular cast flat-top pistons and gave them to the machinist for boring/honing, along with decking. The original valvetrain and heads (3814480) will be reused. The crank (3735236) has been turned 10/10, and the rods checked well. The hydraulic camshaft we’re planning on using has a cam lift of 0.281 intake and 0.296 exhaust, lobe centerline of 107 intake and 117 exhaust. Duration at 0.050-inch tappet lift is 204 intake and 214 exhaust. The engine had a set of headers, but since there aren’t a lot of header options available for a ’62, I think these are Hookers. The previous owner(s) removed the Powerglide and installed a TH350 auto. That’s the background info, and now for the questions.

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