FAQ |
Members List |
Social Groups |
Calendar |
Search |
Today's Posts |
#1
|
||||
|
||||
3/4 cam ?
What does this mean? I heard it again today from my sisters friend who (allegedly) had a 67 corvette with a 3/4 cam. I asked why you running on 6 cylinders? He could not explain what it really is.
So can someone explain what the definition of a 3/4 cam really is. I would just like to know I figure it's some kind of chevy talk for ? thanks patrick |
#2
|
||||
|
||||
Been hearing that all my life...I've wondered myself.
The web is a wonderful source of info- Quote:
__________________
Greg Reid Palmetto, Georgia Last edited by Greg Reid; 07-03-2012 at 07:24 PM. |
#3
|
|||
|
|||
I've been doing old cars since the early 70's and heard that term thrown around alot back then but never understood what it meant, often the person using the term new little else about thier car.
|
#4
|
||||
|
||||
Has 12 out of 16 lobes? hehe
__________________
1968 Firebird 10.817/122.33 3600lbs trw 455, iron d-port heads/SD intake/q-jet, 9" tires 1.440 60ft 1962 Catalina 4100lbs trw 455, iron d-ports,perf RPM, 800holley, 9'' tires,(12.157@108.91)1.578 60' Oct 2010!! |
#5
|
||||
|
||||
Almost a race cam but not quite...
For the last 35 years or so, when you hear someone talking about a "3/4 race cam," it's just a good indication that they don't know what they are talking about. Back in the mid seventies though, I remember that J.C. Whitney had "3/4 race" cams in their catalog, along with "full race." Nowadays, I think the acceptable terminology would be "Street-strip." |
#6
|
|||
|
|||
Kinda like the term " it has an RV cam in it". Does that mean you can only use it off road
Rick |
#7
|
|||
|
|||
or pull your boat out of the water with your Winnebago 'cause ya got the RV cam
|
#8
|
||||
|
||||
The last person to (seriously) ask me about a "3/4 cam" was about 70 years old at the time.
Don't you know that the 3/4 cam is best used with the six pack and camel hump heads on a 327 from a corvette with ram's horn manifolds and cherry bombs?
__________________
I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 |
#9
|
||||
|
||||
I was told by someone older than me that it meant it was raced 3/4 of the time and 1/4 of the time was street time. I guess he didn't know what he was talking about.
__________________
Go Fast... Return... Go Fast Again... Who cares about left turns??? |
#10
|
||||
|
||||
Quote:
__________________
Gentlemen put your trust in God, But mind to keep your Powder dry. Oliver Cromwell Michael Hughes Sr 1966 GTO Convertable: Stolen never recovered 1966 GTO Hard Top .30 over 455 4-Speed 3:23 Posi |
#11
|
||||
|
||||
Been hearing it most of my life as well. And it still makes me laugh when I hear it. Often used with other elusive products such as "Elderblock" intakes and "Ranchero" springs.
__________________
___________________________________ "Objects in mirror are closer than they appear" |
#12
|
||||
|
||||
I remember back in the 60's I had a 1/2 race cam in my 62 Oldsmobile, it had a .030 over 394 and man did it sound mean with that cam. In those days the average hot rodder or wanna be hot rodder had no idea about duration, lift, LSA etc. All they know was that they wanted a hot rod and wanted more horse power. So the guy at the speed shop that knew maybe a little more than Joe Blow off the street would recommend a camshaft. The guy would say this is a 1/4 race, half race or 3/4 race cam depending on which direction the wind was blowing. In those days the average hot rodder had no clue about cylinder head flow, torque curve, high stall torque converters and the like. So we had a 1/4 race or a 1/2 or a 3/4 race cam. It was the magic ingredient to make you go faster and sound cool. You hear that guy's engine idling you knew right off "he had a cam in it". We have come a long ways and the average guy knows more about engines and cars in general than back in those days. It's all part of evolution, we can make fun of them but that was a different era.
__________________
Tim Corcoran |
#13
|
||||
|
||||
This goes back at least to Ed Winfield flathead Ford cams in the 1950s. They offered "full race", "semi" (aka "half race") and eventually "3/4 race" cams for Ford/Mercury flathead V8s.
A stock '50 Ford V8 flatty cam had 239 degree intake duration, 241 degree exhaust duration and .307 lift on both intake and exhaust. The Winfield "full race" cam had 260 degree duration on the intake and exhaust lobes with .305 lift. The Winfield "half race" cam had 252 degree duration on the intake and exhaust lobes with .295 lift. The Winfield "3/4 race" cam had 260 degree duration and .305 lift on the intake and 252 degree duration and .295 lift on the exhaust lobes. So the 3/4 race cam had "full race" intake and "semi" or "half race" exhaust lobes.
__________________
My Pontiac is a '57 GMC with its original 347" Pontiac V8 and dual-range Hydra-Matic. |
#14
|
||||
|
||||
In 1983, I bought a '66 GTO from an older guy who was moving cross-country. He was towing it behind his late 70's Caddy, when the Caddy's tranny went out in my home town, prompting him to sell the GTO in order to get money to fix the Caddy. That is when I first heard the term: "Son, it's got a high-compression 400 and a 3/4 race cam. It'll really scoot!" I was 15 and had no idea what he meant, but it sure was the fastest car I had ever been in at the time. Blew the doors off the typical late 70's Cameros that were thought of as fast in my high school at the time...and it was far more lopey than anything I had heard at the time. Now mind you, I did come from a racing or hot rodding family, and had never even been to a drag strip yet.
After that certain people would hear the car and say something about it having a 3/4 race cam. It was certainly a fairly common way to describe a lopey camshaft appearing in a street car back then, and back them, not many cars had lopey cams, at least not around my parts (Houston suburbs). The funny thing is, to this day, I still do not know what kind of cam that was and what it's actual specs were... |
#15
|
||||
|
||||
Heres one for ya; Got a 32 three window coupe
with a 327 202 heads 3/4 cam and juice brakes. Fast as hell and'll stop on a dime. LOL Got that one from my brother inlaw when I was a kid. Still cracks me up, And he did have some fast cars back in the day. GT. |
#16
|
|||
|
|||
I hear this all the time also. It has a cam in it , just like tim said. I has to have a cam in it to make it run. No Cam No Run.
|
#17
|
||||
|
||||
Quote:
dont forget the 4.11 gears and posi!! |
#18
|
|||
|
|||
The original Crane Company listed a 3/4 race cam in their 1992 inverntory. I was invited to attend a Crane presentation on cam selection in 1992, and among the handouts was a floppy disc with the complete Crane listings. And also received a certificate for attending. I had the Pontiac cam listing printed out, and will post the 3/4 race cam specs, along with the floppy and my "diploma" as a cam selection "expert"!
The cam specs are: 226 intake and 236 exhaust on a 106 lobe separation, and with the intake centered at 101 with the exhaust at 111. This would be a foul idling cam on any stock Pontiac and especially on the 389/400 series. It would also have a shorter operational RPM range then most Pontiac "performance" cams. The information in above posts about the origination of the term "3/4 race" is what I have heard/read over the years. Jim Hand |
#19
|
||||
|
||||
Ya, but what the hell do you know?
__________________
Peace, through close combat. |
#20
|
|||
|
|||
Surprising what we learn from the new generation about how it was in 50s ,60s and 70s,and what the hotrodders knew in the day.Wonder how they gained so much knowledge.
Last edited by badlefthand; 07-04-2012 at 11:04 AM. |
Reply |
|
|