Interesting discussion including some funny comments

http://www.chevelles.com/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=23;t=005506

oops..

Chris...what happened?

OK, I am lost. :confused: Someone fill me in

tongue.gif ....seriously, Jim, someone in another post made a reference to a 3/4 cam. So since most of us, come on admit it, have all heard it and wondered what the heck is that really?? :confused: :confused:

I remembered this post from a while ago, Can you tell I am tired of the winter already..I WANNA RACE :(

Maybe I will move down to Maryland or North Carolina or something

I HATE this term. I will try to keep this short. In my younger days I used to work in a parts store(see where I'm going with this?).I had an older gentlemen come in ask me for a 3/4 cam for his SBC. I asked what he meant by 3/4 and thats when the $%^$ hit the fan. I asked him more and more questions and the useage, I could see the blood flowing to this guys head. After serveral questions I knew this guy had no idea what he wanted, he was just asking for what "his buddies had" or the famous "I have a buddy that runs 9s on this cam". I love asking these questions, but there is a fine you have to walk in order not to put the guy in the hospital. graemlins/thumbsup.gif

I've posted this before but I think it is reference to the T, A and Flathead V-8 days when there were few cams.

Like stock, 1/4, 1/2, 3/4 and full race. Then Isky came out with their famous five-cycle cams..

A 3/4 race cam is about like a CC 268HE but usually were solid cams like a little -097 Duntov, (Imho).

The biggest drawback way back when besides the fact that grinding a race cam was by feel vs how it is done now by computer was the lack of really good springs to hold the valve train together on the OHV motors.. This wasn't that much of a problem on the flathead motors b/c the valve wasn't actuated by a heavy p/r...

pdq67

Someone recently told me that his 256F cam would have been called a 3/4 cam in the 50's and 60's.

I'll read the link later tonight - have to wrangle some leaves before sundown.

Edit:
I came back and read the thread. I'd read it a few days ago after searching "Duntov".

:D

They make 500HP easy. regardless of the motor.

Yes, many funny comments there.

Graybeard's answer mimimcs my thoughts.

Don't ya just love reliving the "good old days" when no one really knew much - like what exactly was lift and duration etc?

Thomas

They make 500HP easy. regardless of the motor.
Yeah...that and my friends cousin has a brother that knows a guy that heard of a guy that runs high 10's in an otherwise stock small block in an impala with one of those.

Back in the late 1920's to early 1930's there was a shop that was considered the cutting edge of race technology ( for back then )...That was Harry Millers shop. Ed Winfield used to work for Harry Miller.Many of the engines they raced were 91 CID straight 8 flatheads...They only spun these little engines into the 6000 RPM range....Being flatheads they had no rocker ratios so lobe lift - lash was valve lift.These cams were very small really...

I'm not positive what the stock lift on most Ford flatheads was but it likely was only on the .300 - .325 lift range with lash in the .008 - .014 range.

Here are a few old aftermarket lobes that have been around for decades for the Ford V8 Flatheads.

3/4 race cam.
Lift .... .325
adv dur... 260
Dur @.050..220
20-60/60-20
Lash @ .014
--------------------------------------------------
3/4 race cam
Lift .... .364
adv dur... 249
Dur @.050..226
17-52/57-12
Lash @ .014
---------------------------------------------------
Full Race Cams
Lift .... .320
Adv Dur... 264
Dur @.050..224
24-60/60-24
Lash .010/.012
---------------------------------------------------
Full Race Cam
Lift..... .400
Adv Dur... 258
Dur @.050..244
18-60/60-18
Lash .018
---------------------------------------------------
Full Race Cam
Lift ......410
Adv Dur....280
Dur @.050..263
lash @ .020
--------------------------------------------------

So if you look at the specs you can see that the so called 3/4 race cams really are hotter than a stock cam and not as roudy as a Full Race Cam.Way back when these terms made sense ... back in the dam when most people had no clue what the specs were anyway.

It wasnt that long ago...well ok it really was when people said..." I dont care what cam you have in your engine... I have a Duntov in MINE !!" Even they most likely had no clue what the specs were.

But yea it's an ancient term that should have been retired decades ago....When so many people haveing access to cam specs there is no need for terms like that anymore.

I thought it referred to the number of strip passes it was guaranteed to survive. smile.gif

Reid

[/QUOTE]Yeah...that and my friends cousin has a brother that knows a guy that heard of a guy that runs high 10's in an otherwise stock small block in an impala with one of those. [/QB][/QUOTE]

Yeah, I know that same guy ;)

I would run into guys from time to time that would tell me about the 3/4 and full race cams they ran and how fast I could run with them. The last time was in the late 1980's and all he was racing was a bar stool and nursing a 3/4 can of Bud.

Originally posted by 69LS1:
Back in the late 1920's to early 1930's there was a shop that was considered the cutting edge of race technology ( for back then )...That was Harry Millers shop. Ed Winfield used to work for Harry Miller.Many of the engines they raced were 91 CID straight 8 flatheads...They only spun these little engines into the 6000 RPM range....Being flatheads they had no rocker ratios so lobe lift - lash was valve lift.These cams were very small really...Wow! A Miller reference. I'm impressed. Here's a quote from "Offenhauser" by Gordon White about Winfields Offy cams.
"There were Winfield 4s, 5s, and other cams for the Offy, depending on the track length and the owner or mechanics preference. The No.4 Winfield had a valve lift of .400 inch and opened the intake valve at 20 degrees before top dead center(BTDC) while the No.5 had a lift of .375 inch and opened the intake at 24 degrees BTDC. The No.4 exhaust valve opened at 48 degrees before bottom dead center(BBDC) and the No.5 at 56 degrees BBDC. The No.5 was said to be better on paved tracks and the No.4 on dirt."
So were talkin' about some seriously small cams here. But, they were high tech back in the 20's.

Jeff

Jpete,

Thats cool stuff !! I like old history like this...
A guy who used to work at the company I work for used to run a SBC Digger back in the early 60's...They kept killing valve train parts...Ed Winfield just happen to walk by thier pit and started BS'ing...Tom mentioned the wounded pieces...Ed asked if he could see the cam...Tom said sure it's sitting right here...( the engine was apart )...Ed looked at the cam and said this aint gonna work...Let me send you a cam...They said OK....They recieved Ed's cam a couple weeks later and they ran quicker and stopped hurting parts !

I wish their was more info about him...By all acounts he seemed to be a master back in his day. graemlins/thumbsup.gif

If you want to see some history, get that Offenhauser book I mentioned. I got it at Barnes&Noble. As a machinist, I'm interested in HOW they made all these things. No CNC's and he's making TUBULAR connecting rods out of raw forgings! Lots of old pictures and tons of history. The book is mind blowing!

Jeff

Here is some history for Ed Winfield

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!
I found some other interesting stuff here:
http://www.harveycrane.com

I'm a HUGE Offy midget fan. If you are interested try
www.milleroffy.com (http://www.milleroffy.com)
Lots of info, pictures and sounds.

Jeff