No. That's 4/7

 

What about the rubber cam? The faster you spin it, the bigger the lobe gets.

 

 

If you find an oldHot Rod magazine from the 60's or even 70's some of the crate motor advertisers used that fraction designation to sell their mail order motors that way. Not sure if the Hot Rod magazine used those terms also but their advertisers sure did. The hobbiest public was pretty naive back then and the market for junk crate motors was fairly profitable.
It wasn't until the 90's that I got to visit those so called engine build shops in the LA basin. I found one shop only had a box strapping machine for a machine shop but the guy at the counter guaranteed me he could get any motor work done I requested - sorry can't recall their name but have several I'd like to call them. A place called Larry's didn't even have a shop to visit. And when I finally located one shop it was to scary looking to get out of the car and go in.
I think the internet has helped identify bad information and bad businesses thought hasty owners still get ripped off.

But ya know I will call a very large duration cam a Full Race Cam as I wouldn't use it on a street motor. Take it or leave it.

 

I'm no expert on the subject, but I think it just means a high performance
Cam that is still streetable and therefore stops short of being a full-race
Cam...

 

I agree T.L.
Unfortunately cam companies are still using the term.



http://www.jegs.com/i/Crane-Cams/271/100082/10002/-1
https://www.iskycams.com/the-racing-cam-series.html
https://www.crower.com/camshafts/for...camshafts.html

At least Crower dumped this term on the not-so-smart Ford and Import crowd.
Chevy people are smarter.

 

Interesting how the only thing that makes that Crane cam nasty is the 106 degree LSA.
Other than that, it's not real aggressive...

 

Lobes do not open .they lift the pushrod to move rockers that open valves. But dont forget about the muffler bearings, they add horsepower !!!!!!

 

this thread was a nice blast from the past to when I had first joined.

I do love the quirky terms they used in my dads old car mags. about the time disco stripes were gracing the covers.

 

TECH QUICKIE: What is a ‘3/4 Race’ Camshaft?

By MIKE MAGDA AUGUST 31, 2015Occasionally the term “¾ race cam” pops up in conversation, usually with veteran hot rodders or nostalgia groups. Sometimes you’ll see it in print ads and online product listings. From a purely technical viewpoint it means little in the way of explaining a camshaft’s performance potential. It’s just one of those glorious reminders of the early days when camshaft grinders had furious rivalries on the track and in the media. It’s also a significant milestone in a developing enterprise that snowballed into what we now recognize as the street-performance market.
The original 3/4 race cams are the forerunners of today’s street-performance grinds.

The term likely originated in the ‘50s as the burgeoning hot-rod industry was modifying Ford Flatheads to drag race on airport runways and attempt top-speed runs on dry lake beds. The legendary Ed Winfield was one the early pioneers in grinding camshafts with more aggressive lobe profiles, and the cams were often labeled as full race for promotional purposes.

“And then some guys wanted a milder cam that could also be used on the street, so they called it a three-quarter race cam because it didn’t have as much duration and lift,” explains John MacKichan of the Speedway Motors Museum of American Speed in Lincoln, Nebraska.

 

Most of them have no idea what cherry bombs sound like.

 

 

I wondered how many decades it might take for someone to determine the V-6 SBC was the correct answer.

 

v6 SBC is always the correct answer.

 

Well, it's 1/4 short of a full race.

 

LOL! Best answer in the whole thread.