Technical Camshaft for Dummies

Uncle Tony is quite a character but is legit, in his knowledge of hi-po engines. Some good basic info here for the novice
Btw..just exactly what is a “3/4” or “full race” cam anyways???



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Ha. I had thought about asking to see who knew. I think I do, and I've never gotten the answer in person.
My guess is that it comes from 270° (about the duration of a "3/4" cam).

Edited: Oh, didn't see the video. I'll see what it says.
Edit 2: I stopped watching. I guess if he defined 3/4, full race you wouldn't have asked. I didn't mention that 270° is 3/4 of a full circle. (360°)
The longer the duration of a cam, the higher up in engine speed it moves the power band. You sacrifice low rpm torque for high rpm horsepower. So a full race (long duration) cam is not suitable for traffic.

 

I had never heard the 270 degree theory for a 3/4 cam. I doubt that is the real reason for the term, but I do like the logic.

 

The first time I heard the term was when I had a cam ground for a 235 Chevy. It was 272°. That's where the theory came from. I think it's better than "Well, that's not a racing cam, but it's 3/4 of one." Haha.

 

Squirrel posted an article about building a 265 a week or so back, reference to the 3/4 cam was mentioned in the article. Think it was a late 50's piece.

It's in this thread:

https://www.jalopyjournal.com/forum/threads/265-chevy-build-ideas.1182504/

 

That seems simple enough!