What is a 3/4 racing cam?

Back from the dead, and I had to share.  On my school's autoshop wall:

I thought it meant you had 6 cylinders of full race and 2 cylinders stock.

3/4 race cams are the ones that will idle 3/4 of the time, when conditions are optimal.  Or was is the ones that you need a loose converter or manual trans for.   No it has to do with how much vacuum it pulls at idle.

E36 M3 I don't know, just give the lump grinders your flow numbers from your heads and intended use and let them work their magic.  If it's not right they will do it again and then you have a "custom ground cam for sale" they are worth more you know.

A 3/4 race cam is a camshaft that we installed in my friend Phil's (this is back in High School) beautiful 69 Firebird 400 and immediately  tested it out on main street and wrecked into the 11 pm train because you no longer have enough vacuum for power brakes. 

Gasoline said:

A 3/4 race cam is a camshaft that we installed in my friend Phil's (this is back in High School) beautiful 69 Firebird 400 and immediately  tested it out on main street and wrecked into the 11 pm train because you no longer have enough vacuum for power brakes. 

Yeah, like I said something to do with how much vacuum it doesn't pull.

A 3/4 race cam is one that you can put a motor in 1/2 a day and then spend the next 3 days fiddling with the carbs and distributor trying to get it to idle.  BTDT.

My 12 year old brain knew a rockin' full race cam was the bomb, something "streetable" was a 3/4 cam; almost a racer.

A terrible photo I took of a 1955 hot rod magazine advertising 3/4 and full race cams.

I have a 56 F100 in the shop and the owner says it has an RV cam. I asked who made it, what are the specs and firing order and all I get from him is "it's an RV cam, you should know". I am guessing it is an Edelbrock performer or a summit branded version thereof but am unwilling to tear the engine apart to find out.  I was just trying to verify firing order on a non running engine. I am of the mind that RV cam is the new 3/4 race nomenclature

So, if I have a rotary somewhere between stock and full race does that make it a 3/4 wank? Err, Wankel

In reply to rustybugkiller :

Let’s be honest, no one likes anything less than a full wank. 

3/4 race has been replaced with the generic, stage numbering system.  A friend of mine is getting into cars, he got a lecture when he asked me about going to a stage 2 kit for his WRX.   Apparently stage 5 is a race car, stage 1 is lame, 2 or three is for the serious enthusiast and stage 4 is a 3/4 race.

My mustang is a stage 2, is has boltons and a tune, once it gets heads and a cam it will be a stage three, if I go bigger cam or a power adder it will get bumped to a 4.  

The whole stage thing is nice for catalog shoppers but offers almost no useful info and drives me nuts.

In reply to akylekoz :

Yep, first question someone asked me after I cammed the Jeep was "what stage cam is it?"  My response: "real parts don't come in stages, they have specs"

akylekoz said:

The whole stage thing is nice for catalog shoppers but offers almost no useful info and drives me nuts.

Most people don't understand the specs or even what the parts do, and aren't interested in finding out, but it gives them the ability to talk about them like they do and it makes it easier for suppliers and manufacturers. Ask a the average motorhead how much duration or what lobe centers he wants and he has no idea. Ask him what stage cam he wants and he will usually have an answer.

914Driver said:

My 12 year old brain knew a rockin' full race cam was the bomb, something "streetable" was a 3/4 cam; almost a racer.

This is what I was taught as a teen. More specifically if you looked at the specs for a OEM vs. full race, it was somewhere around 3/4 between depending on application to keep it street legal. An RV cam would increase low end torque not changing a lot on the high end and still have almost a stock idle.

You know what sucks? Buying a cammed car off of someone and not getting the cam card (I was 16). At least it no longer has an automatic.