Can someone explain what a 3/4 race cam is?

[tyoneal]

To All:

I have heard the term, "I had a 3/4 Race Cam put in the car".

What are they talking about?

This was used a long time ago sometimes when you would have a Car Dealer put in whatever the "Hot Cam", was for a particular engine.

I look forward to any insight into this as I have never understood what heck that meant.

Thanks,

Ty

[redfire69]

Boy this brings back memories.... "gimme a 3/4 race cam!" A phrase oftened used (and mis-used!!) for bottom of the page ordering.... I think it had to do alot with the cam lift and duration compared to full race cams. If I recall this term was used loosely to describe a cam three quarters of the way between a stock cam and full race cam of the day...

I remember @1983 my brother built a backyard 305 SBC with a "3/4 race cam", 350 heads, and topped it with a 2-barrel rochester.... he could rev the heck out of that combo!!

Anyone else?

Ron

[ProdigyCustoms]

Oh this should be a good one! Lots of ideas of what this means, and none right, LOL! I do not pretend to know the correct answer, but have enjoyed all the explainations through the years. Im going to make the popcorn, LOL!

[kennyd]

if i can find it , i have a 3/4 cam in the box i bought at a swap meet just for the thought of having one . and it did say on the cam card 3/4 race cam .
i will look tonight .

[redfire69]

Oh this should be a good one! Lots of ideas of what this means, and none right, LOL! I do not pretend to know the correct answer, but have enjoyed all the explainations through the years. Im going to make the popcorn, LOL!

Yeah, I don't mind being wrong and getting this started.... maybe it means .75 lift ? :P Check out this very discussion at chevelles.com... I'll bring the beer...

http://www.chevelles.com/forums/showthread.php?t=61530

Ron

[mstennes]

This is what I always heard is that it referred to the cams used in the old Flatheads. I had it explained by a friends dad once but cant remember the specifics. It was a term that just stuck around through the years, untill companies started really posting their actual grind numbers, he also explained that allot of cam companies didnt want their grind secret numbers getting out so if one had a winning grind everyone else would buy their cams and it would be harder to copy. I wished I had payed more attention or at least remember the specifics of 1/2, 3/4 and full race. Soooooooo is this wrong or right?

[ProdigyCustoms]

Yeah, I don't mind being wrong and getting this started.... maybe it means .75 lift ? :P Check out this very discussion at chevelles.com... I'll bring the beer...

http://www.chevelles.com/forums/showthread.php?t=61530

Ron

Thanks for that link, LOL!

[Nate_ERC]

Redfire's got it. A 3/4 cam is just an aggressive cam that's supposed to be streetable.

[Ventoso]

To All:

I have heard the term, "I had a 3/4 Race Cam put in the car".

What are they talking about?

This was used a long time ago sometimes when you would have a Car Dealer put in whatever the "Hot Cam", was for a particular engine.

I look forward to any insight into this as I have never understood what heck that meant.

Thanks,

Ty

Hope you don't mind, but I quoted this verbatim and posted it on another forum in a cam grinders section (Jay Allen from Camshaft Innovations). Hopefully he'll reply so we can really get some true insight on this, because to be honest, you've really peaked my curiousity. ;)

Edit, got my answer:
"The term came from camshafts that were used for racing 75% of the time and street use 25% of the time. I still to this day get some of the old moonshine boys call me and want to know if 50/50 cams or 3/4 race cams can still be ground! "

[Garage Dog 65]

We heard that one back in high school and our crew use to make fun of the saying.

We joked that - it would finish about 3/4 of the race - then blow the thing up ....

:lol:

Jim

[DaleLee]

The funny thing is I keep a Crane 103072 cam & lifters in stock... The end of the box still says "282 HO8 3/4R cam & lifters". :lol:

[rwhite692]

A 3/4 cam would be.... for a V6, right?

:lol:

Seriously though, I don't think there is any "concrete" definition, it's a BS term IMHO.

[69MyWay]

Take your pride and joy project car to a car show and sit next to it long enough and at least one toothless redneck will walk up - unsolicited, not even looking at your car and start telling you a story about how his brother's roomate's uncle knew a guy that lived down the road that had a cousin who owned a Camaro just like yours...and they put a


3/4 race came in it

and of course...it was the fastest car in town - a total and comlete mystery to the rest of the world AND it had one of those experimental carbs that Detroit wasn't suppose to let out on the street that got 40 mpg until the dealer confiscated it on a routine oil change! LOL

[69 L88 Camaro]

Dirt track cam, length of the track? 3/4 of a mile?

[G-Body]

These cams were used before most on here would ever know, But was refered to by Zorus arkus dontuv for you Vette guys may ring a bell, his cams used in the hot small block 265's and 283'2 of the day in the early vettes racing programs where given this name seems too have stuck in the high performance world where as there werent to many to choose from back in the day!
And truth be known these cars including the tri fives would really get it! for the times and technogloy available.

[Ummgawa]

G-Body, you hit it. It was a term for the 30/30 Duntov cam from the late 50's early 60's. An old race car guy told me 3/4 cam because of the lobe seperation looking at it down the shaft intake vs. exaust.

The Duntov answer seems more plausable, but, who knows.


Great question!

[ProdigyCustoms]

Over the years, I have heard the Duntuv story the most in relation to the 30 / 30 cam. Weather it is true or not, I do not know, but I have had many historians tell me that.

[$mike70Z28]

this how it goes 1/4 street 1/2 mild 3/4 semi race 4/4 full race i know from a engine builder

[tyoneal]

To All:

I've really enjoyed reading all these post and of course the link that was posted.

One of the earliest times I remember hearing the phrase was in the 60's. When my Grandfather bought the '65 Riviera I now have. I had asked why he didn't buy the Grand Sport (2X4) 425 Nailhead instead of the 4 barrel 425. He mentioned that he had the car delivered to him with a 3/4 Race Cam in it from the dealer, and the car was, "Hotter than a Screwed Sheep!", and having the two fours wouldn't make that much difference over the single 4 barrel, if you had the 3/4 Race Cam.

He was born in 1917 and in WWII, he worked for North American, and spent his time rebuilding the P-51's, and some of the Bombers we had back then. I don't know how old the name is, but I'm positive he owned a mess load of Flatheads that he spent his time Hot Rodding when he had the chance.

As kids when my folks would leave my brother and I with our Grandparents in the Summer, my Grandmother would strap my brother and me in the back seat of the Riviera, and she would cruise around looking for street fights at the stop lights, and the Riv. left nothing but black marks and a bunch of white smoke when we would take off. As kids it was the best fun we ever had, we just couldn't tell anyone about it.:unibrow:

Thinking more about this, I'll shoot off another email to a old time racer I know, I'm almost sure he would have some Idea about this as well.

Thanks again for all your remarks, this had been something I have wondered about for years. When I had my LS-7 (454) it came with a pretty hot cam from the factory, however you could still buy a hotter, "Special Drag Racing Cam", that I knew loped a bit more. As far as lift, I'm not sure what the difference was.

Anyway, I'll keep reading what people have come up with .

Thanks again,

Ty

[HAULNSS]

This is the way I have understood the term "3/4 race cam".

ED WINFIELD
HIS HISTORY AS A CAMSHAFT MANUFACTURER
compiled by
HARVEY J. CRANE, JR.
October 1, 1999

Ed Winfield made his first performance camshafts in 1914. These were motorcycle cams with individual lobes pinned to a shaft.

His first automotive camshafts were ground in 1919 when he built his first homemade cam grinder. Ed was 17 years old at that time.

Ed told me 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 into racing specifications.

Ed told me he first made only two masters, 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".

According to Dema Elgin, ED began working for Harry Miller at the age of 14 1/2 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 like a dictator.

Ed quit grinding camshafts in October of 1969 after he finished a batch of Drake Offenhauser camshafts. That's 55 years of grinding cams!



Randy

[tyoneal]

Randy:

I think you got it nailed. This is what I found from a guy who was the Technical Guy for Mobil Oil Corporation in Charge of Mobil One Racing for 20 years. He was the lead guy for F1, NASCAR etc.
============================================
Here is what he sent me:

The 3/4 Cam

This is an old term back to flathead days, when a 3/4 race cam would run well on the street but increase power over stock for the lakes. A 'full race' cam, or 4/4 cam, would be very lopey on the street, not idle well, and be just for the flat out stuff like the lakes or Bonneville. With new technology and so many variations on timing and lift, plus roller followers, the 3/4 term really means just about nothing. It is now possible to have a smooth idling cam that makes gobs of power, and a lumpy cam that doesn't make power where you normally would use it. Usually, less is more.
============================================

Thanks for all the help.

Best Regards,

Ty

[romar 02 ss]

I could be wrong, but I think it's an early version of the Flux Capasiter.:D