Big-block aluminum intakes with stock hood clearance for C3s?

[Edward B.]

Re: Big-block aluminum intakes with stock hood clearance for C3s?

I just went out and measured the Holley Street Dominator, and as you can see, you could easily have a machine shop shave 1/2" to 3/4" off the carb mounting flange. This will give you the extra room required, but now you're talking machining costs, and by the time you have this done, you could probably buy an original L36 intake for the same amount! That, plus the "unknowns" of shaving the flange is probably not worth it.

Ed

[Mark E.]

Re: Big-block aluminum intakes with stock hood clearance for C3s?

Thanks Ed. I like your creative approach to problem-solving.

[Douglas L.]

Re: Big-block aluminum intakes with stock hood clearance for C3s?

Not to hijack but if you're looking for a L36 intake I've got a nice late 68 one that I'd let go for a reasonable price. Just saying,
Doug

[John D.]

Re: Big-block aluminum intakes with stock hood clearance for C3s?

Joe, I don't know much about carb intakes. Brain washed.
What's a single plane intake please. Thanks, John

[Joe L.]

Re: Big-block aluminum intakes with stock hood clearance for C3s?

Joe, I don't know much about carb intakes. Brain washed.
What's a single plane intake please. Thanks, John

John------

A single plane intake, sometimes referred to as a 360 degree intake, is one in which all of the intake runners are fed from an open plenum under the carburetor. All of the carburetor barrels feed into this open chamber. A single plane intake is usually of a lower profile than a dual plane intake although some racing-only versions are high rise.

A dual plane intake, sometimes called a 180 degree intake, has a divided plenum. Four cylinders, usually 2 on each side, are fed from one side of the plenum, and 4 cylinders, usually 2 on each side, are fed from the other side of the plenum. Half of the carburetor barrels feed into one side of the plenum and half feed into the other side. All GM PRODUCTION manifolds for V-8 engines are dual plane.

[Duke W.]

Re: Big-block aluminum intakes with stock hood clearance for C3s?

Dual plane manifolds make better low/midrange power and single planes more top end power, all other things the same. Which is more useful on a road engine?

Also, dual planes provide better low speed fuel metering due to the strong individual cylinder induction pulses spaced at 180 degrees. These strong peaks get washed out when there is an inlet pulse every 90 degrees.

Note that the Rochester FI manifold is single plane, but it has longer runners than a typical single plane carb manifold. Also, since FI systems, either vintage or modern don't depend directly on the venturi signal to meter fuel, like carburetors, they usually have good low speed fuel metering properties by mechanically or electronicly amplifying the venturi signal.

Duke

[Richard K.]

Re: Big-block aluminum intakes with stock hood clearance for C3s?

Just adding my two cents worth....Put some square port heads on your LS5, an easier to find 70 - 71 3963569 low rise Aluminum intake and a reasonable size Holley. No clearance issues anywhere and you can make it as original looking as your checkbook will allow.

Rich

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[Mark E.]

Re: Big-block aluminum intakes with stock hood clearance for C3s?

Just adding my two cents worth....Put some square port heads on your LS5, an easier to find 70 - 71 3963569 low rise Aluminum intake and a reasonable size Holley. No clearance issues anywhere and you can make it as original looking as your checkbook will allow. Rich

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Interesting idea, Rich.

For my LS5, it's running well so swapping to rectangular heads and installing a cam that works with them is probably deeper than I want to dig into the engine. Also, for this car (AC, wide-ratio, and tall rear end), I'm thinking oval ports, hydraulic cam and a spread bore provide the low-end torque needed for this combo. It's really a touring car with some grunt, rather than a quarter-miler.

For the '73 project (which I haven't yet found- a clean, stock, complete, big-block with a tired, blown, or NOM engine), I again want a responsive big-block that's relaxed on the highway, has AC, and gets gas mileage in the teens (for those off the beaten path road trips I love ). So I'm thinking about the ZZ454 which has an updated 4-bolt block with a hydraulic roller cam and aluminum, open chamber, oval port heads. With a spread-bore Q-Jet and tall gears I'm hoping this combo will meet my needs but have a lot more kick than the standard LS4 (or even LS5 given the roller cam and weight savings). The ZZ454's intake won't fit under the hood, so that's why I'm asking about low-profile aluminum intakes. I guess I could install an iron LS5 intake, but that just seems strange on top of aluminum heads.

I like the idea of this looking stock to the casual eye, so I'll use stock valve covers, air cleaner, shielding, etc.

If I was building an in-town hot rod, I'd go your route and get a crate engine that comes with rectangular port heads, large Holley and then add stump pulling gears. That's just a different set up for a different ride.