WTF is a "3/4 race cam"
07-25-2008, 06:59 PM
#21
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a little off topic, but what the hell are CHEATER SLICKS?? i always hear old school guys talk about putting on a pair of cheater slicks?!?!!
i doubt they are talking about radials cause those weren't around back in the day, were they?
i doubt they are talking about radials cause those weren't around back in the day, were they?
07-25-2008, 08:10 PM
#22
I believe I have the real definition.
A 3/4 race cam is a cam that opens the valves 3/4 of the way that they can possibly mechanically open. A full race cam usually only lasts 10 passes, and you often run into problems with clearancing.
A 3/4 race cam is a cam that opens the valves 3/4 of the way that they can possibly mechanically open. A full race cam usually only lasts 10 passes, and you often run into problems with clearancing.
07-26-2008, 09:24 PM
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A full-race cam would have a high lift and a long duration. A 3/4 race cam would be one with specs about 75% (or 3/4) as big. It means you have a big lumpy camshaft, but its not as big as one a race-only engine would use.
Cheater slicks would be like Mickey Thompson ET Streets. They're made from the same rubber as full slicks, but they have enough tread to pass DOT specs for the street.
Cheater slicks would be like Mickey Thompson ET Streets. They're made from the same rubber as full slicks, but they have enough tread to pass DOT specs for the street.
07-28-2008, 08:17 AM
#25
Everybody knows A 3/4 cam is for a 4.3 liter v6 in a S10 
From what I have been told by some old racers is there used to only be a few cams for any one type of motor.
Kinda like stage 1-2-3-4 and even 5 head porting of today.
Just wait till we are older and kids come up and say what the heck is is a stage 4 head?..
From what I have been told by some old racers is there used to only be a few cams for any one type of motor.
Kinda like stage 1-2-3-4 and even 5 head porting of today.
Just wait till we are older and kids come up and say what the heck is is a stage 4 head?..
Last edited by TTOP350; 07-28-2008 at 12:44 PM.
07-29-2008, 08:32 PM
#26
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Scoggins Dickey and slick summed it up best in back to back posts . . .
I rememebr all this talk about Duntov 20/20 and 30/30 ( afew of yall old timers know what I am talking about) that my uncle and dad used to run in their cars. They always told me how bad *** they were and when i finally found the specs I about died . . . . lol .
LOTS of seat duration, not much at .050 or .200 and not much lift. these were cams that probably worked with the junky springs they had back in the day but that is about it.
Kinda like the "big mouth 2bbl carbs" from a Pontiac they used to run and a 57 Olds rear end they used to put in their 55-57 Chevy. I am sure they were upgrades over the 265/283 2 bbl carbs and stock 55-57 Chevy rear end but NOTHING and I mean NOTHING like the cams, springs, carbs and rear ends that were available just a few years later and available to use now.
Lloyd
I rememebr all this talk about Duntov 20/20 and 30/30 ( afew of yall old timers know what I am talking about) that my uncle and dad used to run in their cars. They always told me how bad *** they were and when i finally found the specs I about died . . . . lol .
LOTS of seat duration, not much at .050 or .200 and not much lift. these were cams that probably worked with the junky springs they had back in the day but that is about it.
Kinda like the "big mouth 2bbl carbs" from a Pontiac they used to run and a 57 Olds rear end they used to put in their 55-57 Chevy. I am sure they were upgrades over the 265/283 2 bbl carbs and stock 55-57 Chevy rear end but NOTHING and I mean NOTHING like the cams, springs, carbs and rear ends that were available just a few years later and available to use now.
Lloyd
07-29-2008, 09:41 PM
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a three quarter cam was something that you could still run on the street, barely- needed exhaust, intake work and gears, would idle badly at like 1800 RPM- still, maybe, had enough vacuum to run power brakes- anything more was full-race, i.e., not streetable-
Also very common was a quarter cam, more than stock, but not too radical- would probably require solid lifters (or tappets, for the old guys)- that is what the 302 Z28 engine came with, from the factory, as did the old 426 hemis- which meant you spent a lot of time adjusting your valves- as well as fooling around with carburetor jets, and weights and springs on the mechanical advance on your distributor- Yeah, been there, done that-
Also very common was a quarter cam, more than stock, but not too radical- would probably require solid lifters (or tappets, for the old guys)- that is what the 302 Z28 engine came with, from the factory, as did the old 426 hemis- which meant you spent a lot of time adjusting your valves- as well as fooling around with carburetor jets, and weights and springs on the mechanical advance on your distributor- Yeah, been there, done that-
07-29-2008, 10:50 PM
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The only one that even came close to getting this correct was 'gold86vette'..
3/4 cam referred to a performance cam with 270 degrees of advertised duration @.020 valve lift, duration @.050" would be around 230 degrees..
Ther weren't a whole lot of cams to choose from or people that understood duration, so the manufacturer coined them as 3/4 race cams during that era...
3/4 cam referred to a performance cam with 270 degrees of advertised duration @.020 valve lift, duration @.050" would be around 230 degrees..
Ther weren't a whole lot of cams to choose from or people that understood duration, so the manufacturer coined them as 3/4 race cams during that era...
example: a guy I work with asked me about the cam in my truck and I said the specs, he picked up on the .600 lift and said....Wow, that's a big cam. back in the day a .600 lift cam had 250-260+ duration at .050" You can't even start to explain lobe rates etc. with a roller cam, etc, etc,etc and them not have the deer in the healights look.
They will usually respond about this buddy that had this bad *** dodge with a Purple cam in it.
07-30-2008, 08:23 PM
#30
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Sorry guys I've been out of pocket. Being what some would call a mechanical expert and race historian, I would have answered much earlier.
The age old 3/4 race cam question... Belive it or not the infamous "3/4 Race Cams" (important to include the "s" on cams) is a term created long ago by a man named Ed Winfield.
Ed made his first performance camshafts in 1914 at a very young age. These were motorcycle cams with individual lobes pinned to a shaft. Wow, now that was some really heavy duty cams.
Ed began working for Harry Miller at the age of 14 in the carburation department. Within a few months he was doing other machine work on the famous Miller racing engines. Harry wanted Ed to stay on with him and offered Ed more money. Ed was being paid .60 cents per hour and was offered .70 cents, but ED wasn't fond of Harry because he was sort of a dick, so the stories were told.
His first automotive camshafts were ground in 1919 he finally got rid of the ole hand file and built his first homemade cam grinder. Ed was 17 years old at that time.
Ed's his mother gave him the money to purchase a used grinding machine that he converted to a cam grinder by adding a rocker table. This homemade cam grinder was used in his mother's garage to regrind Ford Model T camshafts which were called Line Lobes into racing specifications. The term was later changed to camshaft. Ed began building a solid camshaft rather than the lobe/pin design of the past.
Ed first made only two master sets, a SEMI RACE GRIND and a FULL RACE GRIND! He later made a third master that was more duration and lift than the SEMI but less than the FULL. He then used the FULL RACE master as an intake and the new master as an exhaust.
He called this new reground camshaft a THREE QUARTER RACE CAM! Ed said "It was three quarters of the way to a full race cam". Thus the infamous term was born!!
Ed quit grinding camshafts in October of 1969 after he finished a batch of Drake Offenhauser camshafts. That's 55 years of grinding cams! The man really knew his ****.
Now you know the rest of the story....
The age old 3/4 race cam question... Belive it or not the infamous "3/4 Race Cams" (important to include the "s" on cams) is a term created long ago by a man named Ed Winfield.
Ed made his first performance camshafts in 1914 at a very young age. These were motorcycle cams with individual lobes pinned to a shaft. Wow, now that was some really heavy duty cams.
Ed began working for Harry Miller at the age of 14 in the carburation department. Within a few months he was doing other machine work on the famous Miller racing engines. Harry wanted Ed to stay on with him and offered Ed more money. Ed was being paid .60 cents per hour and was offered .70 cents, but ED wasn't fond of Harry because he was sort of a dick, so the stories were told.
His first automotive camshafts were ground in 1919 he finally got rid of the ole hand file and built his first homemade cam grinder. Ed was 17 years old at that time.
Ed's his mother gave him the money to purchase a used grinding machine that he converted to a cam grinder by adding a rocker table. This homemade cam grinder was used in his mother's garage to regrind Ford Model T camshafts which were called Line Lobes into racing specifications. The term was later changed to camshaft. Ed began building a solid camshaft rather than the lobe/pin design of the past.
Ed first made only two master sets, a SEMI RACE GRIND and a FULL RACE GRIND! He later made a third master that was more duration and lift than the SEMI but less than the FULL. He then used the FULL RACE master as an intake and the new master as an exhaust.
He called this new reground camshaft a THREE QUARTER RACE CAM! Ed said "It was three quarters of the way to a full race cam". Thus the infamous term was born!!
Ed quit grinding camshafts in October of 1969 after he finished a batch of Drake Offenhauser camshafts. That's 55 years of grinding cams! The man really knew his ****.
Now you know the rest of the story....
07-30-2008, 08:44 PM
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i beleive that the term is what old heads used to try and make their car seem wicked
in all reality, i'm pretty sure it is just a cam ground on a 3/4inch base circle
the guy who says his car has a 3/4 race cam is usually the guy that says his car runs 9's but he forgets his 60 ft and mph.
i'm only 24, not the ower of that fastest home built car in the world, but i beleive i'm right on the 3/4 inch base circle
in all reality, i'm pretty sure it is just a cam ground on a 3/4inch base circle
the guy who says his car has a 3/4 race cam is usually the guy that says his car runs 9's but he forgets his 60 ft and mph.
i'm only 24, not the ower of that fastest home built car in the world, but i beleive i'm right on the 3/4 inch base circle
07-31-2008, 12:50 PM
#33
Sorry guys I've been out of pocket. Being what some would call a mechanical expert and race historian, I would have answered much earlier.
The age old 3/4 race cam question... Belive it or not the infamous "3/4 Race Cams" (important to include the "s" on cams) is a term created long ago by a man named Ed Winfield.
Ed made his first performance camshafts in 1914 at a very young age. These were motorcycle cams with individual lobes pinned to a shaft. Wow, now that was some really heavy duty cams.
Ed began working for Harry Miller at the age of 14 in the carburation department. Within a few months he was doing other machine work on the famous Miller racing engines. Harry wanted Ed to stay on with him and offered Ed more money. Ed was being paid .60 cents per hour and was offered .70 cents, but ED wasn't fond of Harry because he was sort of a dick, so the stories were told.
His first automotive camshafts were ground in 1919 he finally got rid of the ole hand file and built his first homemade cam grinder. Ed was 17 years old at that time.
Ed's his mother gave him the money to purchase a used grinding machine that he converted to a cam grinder by adding a rocker table. This homemade cam grinder was used in his mother's garage to regrind Ford Model T camshafts which were called Line Lobes into racing specifications. The term was later changed to camshaft. Ed began building a solid camshaft rather than the lobe/pin design of the past.
Ed first made only two master sets, a SEMI RACE GRIND and a FULL RACE GRIND! He later made a third master that was more duration and lift than the SEMI but less than the FULL. He then used the FULL RACE master as an intake and the new master as an exhaust.
He called this new reground camshaft a THREE QUARTER RACE CAM! Ed said "It was three quarters of the way to a full race cam". Thus the infamous term was born!!
Ed quit grinding camshafts in October of 1969 after he finished a batch of Drake Offenhauser camshafts. That's 55 years of grinding cams! The man really knew his ****.
Now you know the rest of the story....
The age old 3/4 race cam question... Belive it or not the infamous "3/4 Race Cams" (important to include the "s" on cams) is a term created long ago by a man named Ed Winfield.
Ed made his first performance camshafts in 1914 at a very young age. These were motorcycle cams with individual lobes pinned to a shaft. Wow, now that was some really heavy duty cams.
Ed began working for Harry Miller at the age of 14 in the carburation department. Within a few months he was doing other machine work on the famous Miller racing engines. Harry wanted Ed to stay on with him and offered Ed more money. Ed was being paid .60 cents per hour and was offered .70 cents, but ED wasn't fond of Harry because he was sort of a dick, so the stories were told.
His first automotive camshafts were ground in 1919 he finally got rid of the ole hand file and built his first homemade cam grinder. Ed was 17 years old at that time.
Ed's his mother gave him the money to purchase a used grinding machine that he converted to a cam grinder by adding a rocker table. This homemade cam grinder was used in his mother's garage to regrind Ford Model T camshafts which were called Line Lobes into racing specifications. The term was later changed to camshaft. Ed began building a solid camshaft rather than the lobe/pin design of the past.
Ed first made only two master sets, a SEMI RACE GRIND and a FULL RACE GRIND! He later made a third master that was more duration and lift than the SEMI but less than the FULL. He then used the FULL RACE master as an intake and the new master as an exhaust.
He called this new reground camshaft a THREE QUARTER RACE CAM! Ed said "It was three quarters of the way to a full race cam". Thus the infamous term was born!!
Ed quit grinding camshafts in October of 1969 after he finished a batch of Drake Offenhauser camshafts. That's 55 years of grinding cams! The man really knew his ****.
Now you know the rest of the story....
bingo! We have a winner.....
Now, for the rest of you "yung' uns" who asked about "cheater slicks".....way back "in the day", before there were drag radials, recappers would re cap tires with a somewhat wider, somewhat softer compound rubber, with just a hint of a tread to make them "legal" for A) street use, so you could drive back and forth to the track with them; and B) use in classes that required treaded (today, DOT) tires. They weren't really slicks, but they really weren't street tires either, so if you ran them, you were sort of "cheatin", so to speak.
Any of you old enough to remember the Atlas "Bucrons" ???
07-31-2008, 04:53 PM
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Alot of people refer to cheater slicks today as cars with a soft-compound tire (i.e., idk, BFG KDW2's) where the owner then went about shaving down the tread to somewhere around 3/64" or so, such that there's a limited amount of tread to increase contact patch, and thusly, traction.
Also, on the note of the above poster...
2-strokes have no valves to hold open or closed.
Also, on the note of the above poster...
2-strokes have no valves to hold open or closed.
08-01-2008, 03:29 PM
#39
6600 rpm clutch dump of death Administrator
Sorry guys I've been out of pocket. Being what some would call a mechanical expert and race historian, I would have answered much earlier.
The age old 3/4 race cam question... Belive it or not the infamous "3/4 Race Cams" (important to include the "s" on cams) is a term created long ago by a man named Ed Winfield.
Ed made his first performance camshafts in 1914 at a very young age. These were motorcycle cams with individual lobes pinned to a shaft. Wow, now that was some really heavy duty cams.
Ed began working for Harry Miller at the age of 14 in the carburation department. Within a few months he was doing other machine work on the famous Miller racing engines. Harry wanted Ed to stay on with him and offered Ed more money. Ed was being paid .60 cents per hour and was offered .70 cents, but ED wasn't fond of Harry because he was sort of a dick, so the stories were told.
His first automotive camshafts were ground in 1919 he finally got rid of the ole hand file and built his first homemade cam grinder. Ed was 17 years old at that time.
Ed's his mother gave him the money to purchase a used grinding machine that he converted to a cam grinder by adding a rocker table. This homemade cam grinder was used in his mother's garage to regrind Ford Model T camshafts which were called Line Lobes into racing specifications. The term was later changed to camshaft. Ed began building a solid camshaft rather than the lobe/pin design of the past.
Ed first made only two master sets, a SEMI RACE GRIND and a FULL RACE GRIND! He later made a third master that was more duration and lift than the SEMI but less than the FULL. He then used the FULL RACE master as an intake and the new master as an exhaust.
He called this new reground camshaft a THREE QUARTER RACE CAM! Ed said "It was three quarters of the way to a full race cam". Thus the infamous term was born!!
Ed quit grinding camshafts in October of 1969 after he finished a batch of Drake Offenhauser camshafts. That's 55 years of grinding cams! The man really knew his ****.
Now you know the rest of the story....
The age old 3/4 race cam question... Belive it or not the infamous "3/4 Race Cams" (important to include the "s" on cams) is a term created long ago by a man named Ed Winfield.
Ed made his first performance camshafts in 1914 at a very young age. These were motorcycle cams with individual lobes pinned to a shaft. Wow, now that was some really heavy duty cams.
Ed began working for Harry Miller at the age of 14 in the carburation department. Within a few months he was doing other machine work on the famous Miller racing engines. Harry wanted Ed to stay on with him and offered Ed more money. Ed was being paid .60 cents per hour and was offered .70 cents, but ED wasn't fond of Harry because he was sort of a dick, so the stories were told.
His first automotive camshafts were ground in 1919 he finally got rid of the ole hand file and built his first homemade cam grinder. Ed was 17 years old at that time.
Ed's his mother gave him the money to purchase a used grinding machine that he converted to a cam grinder by adding a rocker table. This homemade cam grinder was used in his mother's garage to regrind Ford Model T camshafts which were called Line Lobes into racing specifications. The term was later changed to camshaft. Ed began building a solid camshaft rather than the lobe/pin design of the past.
Ed first made only two master sets, a SEMI RACE GRIND and a FULL RACE GRIND! He later made a third master that was more duration and lift than the SEMI but less than the FULL. He then used the FULL RACE master as an intake and the new master as an exhaust.
He called this new reground camshaft a THREE QUARTER RACE CAM! Ed said "It was three quarters of the way to a full race cam". Thus the infamous term was born!!
Ed quit grinding camshafts in October of 1969 after he finished a batch of Drake Offenhauser camshafts. That's 55 years of grinding cams! The man really knew his ****.
Now you know the rest of the story....
Now, that trickled down into the mainstream and just about any cam that had any lope and still ran was a "3/4 race cam". If you looked at the old Comp Hydraulics for an SBC back in the 80's they only had had a few basic grinds that everyone used 252H,260H,262H,270H,280H,292H and 305H. Most everything below a 270 was a stock or RV cam. So, that left you a 270, 280, 292 and a 305. The 292 was a 3/4 race, and the 305 was a "full race" for example. Keep in mind the 292 is 292 @ .006 and a whopping 224 @ .050. So, a 224/230 114 is a 3/4 race cam
. But the same token in other crowds the Duntov 30/30 was a 3/4 race cam since there is a larger grind than the 30/30 that was released. Again, its all a matter of the person's perspective on what a "full race" cam was and how much drivabilty was required. Its much the same today when people ask what the biggest cam is you can run in a dailydriver. It really all depends on the person driving the car. I've driven a 346 with a 244/248 112. Some folks would find that unbearable. I drove it just fine. But its all a matter of perspective.So, 3/4 race can mean a lot of things to a lot of people. The best description is probably the ragged edge of "streetable" whatever that is...
Cheater slicks were recapped tires with soft compound tread and two thin groves. They made funky burnouts withthe two stripes down the middle. Popular ones were Atlas Bucrons and Caessler. A good point of refernce today would be an M&H Racemaster. Lots of tread, and just enough tread groove to get a DOT stamp.
BTW, before today's drag radials we used R-Compound road race tires, and also Radials that were re-capped with a compound similar to D20 Goodyear slick compound.
Last edited by J-Rod; 08-01-2008 at 03:35 PM.
08-01-2008, 09:47 PM
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I agree, Using "3/4 race cam" term today or even back in the 80's when we were buiding and racing cars, was not a very good thing to say around us. Someone in the crowd would always break it out once in a while and we would all look at each other with that look on our faces that said, OH NO NOT ONE OF THESE!
Its just an old term that was used years ago before every day normal people new proper specs of cams. Today, most every day normal people are exposed to lift, duration, lobe seperation angle, ect...Thats pretty much it in a nutshell!
Its just an old term that was used years ago before every day normal people new proper specs of cams. Today, most every day normal people are exposed to lift, duration, lobe seperation angle, ect...Thats pretty much it in a nutshell!