Thread: 3/4 cam:fact or fiction?

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Okay fellas, maybe yall can enlighten me on something. My dad and other 40+ guys I have met, talk about cars they had back in the 60's and 70's, that had 3/4 cams in them. I have asked them what they mean by "3/4 cam" but no one can explain it to me. Is this just a generic term for a hot cam, or was there really such a thing?

Where I grew up (70's, Houston) a 3/4 Cam was used to generically identify a more radical street cam. Back then it was taboo to let people know exactly what was under your hood (for reasons that still illude me today). So the cam specifics were of course held confidential.

Kitz

Somebody correct me if I'm wrong, but I believe the 3/4 race and full race cam terms came about in the days of the flathead... Back then rodders were not blessed with the multitude of camshaft and valve train components we have today. As far as what the specs were, no idea... I'm just a geezer, not a super geezer!!!!

As to why I wouldn't tell what was under the hood... It cost $$$$ to find out, usually a bit of bucks up action on the old two lane north of town....If ya won, you could look, if not it was still my secret!!!!!

here's my theory on the "3/4 race cam"....

A relatively hot street cam has somewhere in the ballpark of 270 degrees duration....maybe more, maybe less (depends who you ask)...anyways,

...the "3/4 race cam" has 3/4 of 360 degrees duration (adv) = 270 degrees

Just something I thought about...makes sense to me...but then again, I wasn't around when the mysterious grind hit the market.

Originally Posted by Dave Severson

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As to why I wouldn't tell what was under the hood... It cost $$$$ to find out, usually a bit of bucks up action on the old two lane north of town....If ya won, you could look, if not it was still my secret!!!!!

Yeah I remember now. It was difficult if not impossible at times to negotiate the purse also.

Terminology was a big thing back then, it helped if you didn't know what you were talking about, you could spew a few "facts", and if you sounded convincing, the rest in the group would nod and agree. Cam lore was a "black art". Very few really understood what it was all about. Kind of like today. Stock cams were just that, stock cams, everybody just knew, that there was something better than those. Full race cams were just to much for the street. So the idea of the 3/4 cam, or 3/4 race cam was born. The grind could be anything, as long as it was hotter than a stock cam. The reason no body can tell you what it was, nobody really knows. There wasn't a set of numbers to grind a cam to that made it a "3/4". The cam grind was somewhere between a stock cam and a full race. If you can get to find some of the older ads from cam manufactures, you will likely see where the cams offered were described as 3/4 race and full race. No specs. just the terminology. That was part of growing up back then, if you knew a bunch of the key words, and if you really did know how some of this stuff worked, you could be a big shot. That's how we all learned, I personally blew more money and time on combo's that didn't work, than did. But I was busy! To busy to get into trouble, except to see if the "improvments" really worked. You can read that as "SPEEDING FLAT OUT" or running the sort of "MEASURED" 1/4 mile that's just outside of every small town, or any town for that matter. You knew it was a real 1/4 mile if it was painted on the pavement!! Yeah, we were a little naive, but it was fun. Not something you can get away with today. So, the short answer to "was there such a thing as a 3/4 cam" yep! But you'll never nail down an exact grind.

i still have a new 3/4 cam that on the cam card says " 3/4 race cam " it is stuffed away in a box in the barn . i will go this weekend and see if i can find it and grab the cam card and post a photo of it . i bought it at a swap meet only because it had the card that was printed 3/4 race cam .

Originally Posted by 65cayne

here's my theory on the "3/4 race cam"....

A relatively hot street cam has somewhere in the ballpark of 270 degrees duration....maybe more, maybe less (depends who you ask)...anyways,

...the "3/4 race cam" has 3/4 of 360 degrees duration (adv) = 270 degrees

Just something I thought about...makes sense to me...but then again, I wasn't around when the mysterious grind hit the market.

Strangely enough, that math seems to work (kind of). Cran's largest cam for a 454 Chevy is advertised at 360* (exhaust only).

Having been there back in the day, though, 3/4 race meant nothing more than something quite a bit hotter than stock, but still driveable on the street.

I kinda figured it was a terminology thing. Still waiting for Denny,Don,and uncle Bob to put in their 2 cents.

Originally Posted by Dave Severson

Somebody correct me if I'm wrong, but I believe the 3/4 race and full race cam terms came about in the days of the flathead... Back then rodders were not blessed with the multitude of camshaft and valve train components we have today. As far as what the specs were, no idea... I'm just a geezer, not a super geezer!!!!

As to why I wouldn't tell what was under the hood... It cost $$$$ to find out, usually a bit of bucks up action on the old two lane north of town....If ya won, you could look, if not it was still my secret!!!!!

That's how I remember it. Seems like I also remember hearing about a 1/2 race cam somewhere in my youth.

Tech is right..... in the last century, you had an Honest Charlie catalog or an Isky catalog, etc. For an engine, the number of cam grids was severely limited. Their catalog listing didnt give a lot of cam timing data, it simply said "race" or "3/4 race" or sometimes "short track" for the roundy guys. The buyers werent as scientific as today so you bought a cam. Slicks were similar, you didnt buy a compound, you simply bought slicks.

Somebody probably has an old catalog laying around....Honest Charlie catalog would be fun to see!

Originally Posted by robot

Tech is right..... in the last century, you had an Honest Charlie catalog or an Isky catalog, etc. For an engine, the number of cam grids was severely limited. Their catalog listing didnt give a lot of cam timing data, it simply said "race" or "3/4 race" or sometimes "short track" for the roundy guys. The buyers werent as scientific as today so you bought a cam. Slicks were similar, you didnt buy a compound, you simply bought slicks.

Somebody probably has an old catalog laying around....Honest Charlie catalog would be fun to see!

Think I have one stashed away somewhere yet... sure did buy a lot of go fast goodies from them in the 60's!!!! There just wasn't a lot of speed shops in Valley Springs, SD (pop. 500 at the time), and the internet didn't work!!!!!

A 3/4 cam had 12 lobes instead of 16?

i actually had a 41 ford with a 53 merc flathead bronze block, 3/4 race wolverine cam, wiend aluminum heads,triple dueces,mallory dual point with 4:11 rears .Nice right? wrong -stock tranny.this was in 66. i bought it that way. Great hole shots

Originally Posted by Henry Rifle

A 3/4 cam had 12 lobes instead of 16?

Yup, now I get it!!!! A V-8 3/4 race cam is for a V-6. a 1/2 race came is for a 4 poppler!!! Thanks Jack, you always explain things so well they become clear as mud to me!!!!!!!