Q&A

Mailbag: Lowering ETs with a New Cam & Intake Manifold

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Q: My current project is giving me trouble.

I have a 1953 Chevy 1/2-ton truck with a 283 at .030 overbore and .010 under rods and mains. I’m running early power pack heads, a port-matched stock single quad intake, a 600 cfm Carter AFB carb, and a 45,000V ACCEL coil.

I ran the truck at my local strip and turned a lousy 15.9 at 83 mph. When I hit fourth gear, it didn’t gain any speed.

I checked the plugs at the finish line and they looked fine. My current hydraulic cam specs are .450″/.460″ lift and 224°/224° duration at .050″.

I think I may be using the wrong cam or that my carb is too big. What do you suggest?

A: Your current carb is the ideal size for your engine.

But to shave time off of your ETs, you need a cam designed to generate maximum performance throughout the powerband.

A Crane PowerMax cam and lifter kit has specialized lobe patterns to precisely balance intake and exhaust flow for superior power at any rpm.

You can speed up your times even more with an Offenhauser 360° Equa-Flow single quad high-rise intake manifold. The 360° divided-plenum design provides equal fuel flow to each cylinder, eliminating flat spots in the rpm range — which means more horsepower and torque from start to finish.

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7 Comments

  1. I know it is expensive, but I would start with better set of aluminum cylinder heads. With new valve springs and add 1.6 ratio rocker arms to get more lift from your existing cam (that already has a decent duration at 224 degrees)you should notice the improvement. I would also make sure that the ignition advance curve is proper for the set up.

  2. Alan hougardy says:

    Leave the motor alone and put some gears in it

    • You’re right. First thing I thought of, he didn’t mention what type of trans or axel ratio there is. That could really be dragging it down. I’m running a 305 with a similar sounding cam spec in a 39 Chevy. A 5 spd trans and 3.73 gear and can manage 14.63 in 3 Rd gear.

  3. Michael Madajewski says:

    How far to go? It really depends on where you use the truck most & how much you want to spend. Aluminum heads: be sure to get decent compression of about 9.5-10:1 for a good balance between drivability & performance. AFR 180’s would be the tops for that if you want to spend the money. If swapping cams, upgrade to 1.6:1 roller rockers with a Comp Cams XE hydraulic roller; I’d think the XE270HR for the 283. I’m running the next level up, but it’s for a 383; the XE276HR I run might be a little much for the smaller displacement with regard to idle & vacuum. Manifold to match the rpm range of the cam. I run an Edelbrock RPM Air Gap with a 1″ HVH Supersucker spacer to catch the best of both worlds. Ignition – if you upgrade here I’d recommend a Davis Unified HEI; they will custom curve it to your cam & compression.. it is the best K.I.S.S. option there. Carb is fine at 600cfm. Gears as needed to get about 10:1 in first for a good launch… that really depends on your transmission gearing; again, a balance between 1/4 mile performance and street manners. All the mods need to work together.

  4. fred alvis says:

    cams, heads. coils, 1/6 rocker arms? just buy a crate engine and be done with it.

  5. fred alvis says:

    just buy a crate engine and be done with it.

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