Q: I’ve found that many of the best intake choices for the Ford 351C are for the engine with 4V cylinder heads. What is the biggest difference between the 2V and 4V heads? I know the valves in the 4V heads are bigger, but what other differences are there? Can the 2V head be machined to 4V specs, and can a 2V engine block be drilled for use with a 4V intake?

A: Starting with the basics, 2V heads are designed for use with a factory 2-barrel carburetor option (2V = 2 venturi), while 4V heads came on one of the five Ford 351C engine configurations that came with a 4-barrel carburetor (4V = 4 venturi). The biggest physical difference between the 2V and 4V Cleveland heads is the huge intake and exhaust ports on the 4V heads. There simply isn’t enough material around the smaller 2V ports to hog them out to mate to 4V port dimensions. Since all Cleveland blocks are the same, you can swap 2V heads for 4Vs and vice-versa, but you’ll also need to make sure you have the right exhaust manifolds/headers to match.

There are some good 2V intake manifolds out there. If you want a dual plane intake, the Edelbrock Performer is a good choice. It builds power from idle to 5,500 rpm. If you want a single plane, get the Weiand X-Celerator. It builds power between 1,500 and 7,000 rpm.

This is another in a series of weekly Q&A Mailbag sessions with Summit Racing‘s tech department, in which there are hundreds more. Click here to see them all

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