!970's Pro-Stock Camshaft Spec.'s

[swampbuggy]

I remember in my High School days attending the IHRA Winter Nationals in 1973 or 4 ? in nearby Lakeland Florida. The Pro-Stock cars that i remember for sure were Sox and Martin....Rod Shop car....Grumpy's toy....maybe Lee Sheppard ?....i know there were others too. Those engines really had a Nasty, popping, choppy sound when staging . They sounded Bad-Ass, but ran so-so. Do any of you older gents such as Adger Smith and the like remember what the Lift / Duration / Lobe Separation Angle numbers were back then ? Mark H.

[Walter R. Malik]

I remember in my High School days attending the IHRA Winter Nationals in 1973 or 4 ? in nearby Lakeland Florida. The Pro-Stock cars that i remember for sure were Sox and Martin....Rod Shop car....Grumpy's toy....maybe Lee Sheppard ?....i know there were others too. Those engines really had a Nasty, popping, choppy sound when staging . They sounded Bad-Ass, but ran so-so. Do any of you older gents such as Adger Smith and the like remember what the Lift / Duration / Lobe Separation Angle numbers were back then ? Mark H.

Most of them ran solid flat tappet cams ... the General Kinetics single pattern 332-B grind was popular in all brands; except the cammers, of course.

332@lash - 286@.050" - .371" lobe lift. Available with both 108 and 110 separation.

Good enough valve springs was the biggest issue back then.

[fabr]

'73-'74 we were running rollers,why would the prostocks have been running FT at that time? Yes,springs were an issue for sure.

[Stan Weiss]

Don't know what Pro Stock was running. I was running a GK 320M 372L which was 280 @ 0.050" and .558 with 1.5:1 rockers

I bought a used GK Roller C1R321B 321R-434L 336R-424L which was a cast core and around 283 I and 294 E @ 0.050" but I never got to try.

Stan

[hoffman900]

Harold Brookshire was the designer at GK starting in 1974, before he went to Comp. He wrote this in 2007 answering what cam Grumpy Bill ran:

Yes, they are, the C1R321D, which everyone ran, and his secret grind, the C1R323J, just a couple of degrees larger......
Grumpy Jenkins, Gapp & Roush, Booth & Arons, Maskins & Kanners, were the 4 sponsored teams at GK, with Ritchie Zul getting a little product now and then. I also handled Tony Christensen during his 1976 Comp Elim championship.
I answered all the tech calls, went to all the NHRA National events, and occassionally did a few cam designs......
I have a 322F that I designed in honor of the GK C2M332B, their most famous cam. Their 332B is 332 at .020, 286 at .050,.631 valve lift, and 108 LSA. My 322F is 322 at .020, 288 at .050, 195 at .200, .630 valve lift, and of course, 108 LSA. Any nostalgia racers out there?

UDHarold

He said he had the computer printouts for all their designs. Not sure what ever happened to all that stuff.

[Stan Weiss]

Might want to take a look at this thread.

Early 70's modified or gasser camshafts
viewtopic.php?t=43881

Stan

[Walter R. Malik]

'73-'74 we were running rollers,why would the prostocks have been running FT at that time? Yes,springs were an issue for sure.

When Pro Stocks went to small blocks in lighter cars, they were usually roller cams. The Kinetics 319A was everywhere.

[treyrags]

Not pro stock, but late 70's modified/comp. 285ish @ 50, 775ish lift. But that doesn't tell nearly all of the story. Ramp rate was a big deal, Especially given the valve springs available at the time. We usually had a cam that we would put in to qualify that we knew would kill springs. Then change over to one that might be .10 slower but would last through eliminations.

[maxracesoftware]

i heard some were using the General Kinetics GK 321D Solid Roller Cam

[Walter R. Malik]

i heard some were using the General Kinetics GK 321D Solid Roller Cam

Some ... The 321D (Intake was rated at 282@.055"), was the predecessor to the 319A (which had about .030" more lobe lift on the intake side at .472", was rated 282@.057"). Both used the same 329 exhaust lobe.

We used a 318D (intake rated 280@.055"), in our 292" Modified engine; same family as the 321D just a few degrees smaller.
Went to the 315A (intake rated 278@.052"), which again was the same family as the 319A just a few degrees smaller. Again, both used the same 327 exhaust lobe.

I never understood exactly why they rated their lobes at different heights.

[piston guy]

I still have a 319D and 321D I got from Dyno Don ( rip) Both were from the Pinto days and tagged "valve spring killer" on both.

[swampbuggy]

Laughing a lot ^^^^^^^^^. Mark H.

[Walter R. Malik]

I still have a 319D and 321D I got from Dyno Don ( rip) Both were from the Pinto days and tagged "valve spring killer" on both.

With that Cleveland rocker ratio, I can fully understand; 1.6/1 was about our limit on a SBC.

[Krooser]

I bought a GK Ford Cleveland cam in a parts lot at the old Dave Dayton Indy swap meet in the early 80's.

It was marked "Bob Gidden Pro-Stock" on the tag and came from a Ford ARCA team.

I tried it in my dirt sportsman engine but the valve was too high and valves hit pistons. I sold it to a local Ford drag racer.

[Krooser]

I bought a GK Ford Cleveland cam in a parts lot at the old Dave Dayton Indy swap meet in the early 80's.

It was marked "Bob Gidden Pro-Stock" on the tag and came from a Ford ARCA team.

I tried it in my dirt sportsman engine but the valve lift was too high and valves hit pistons. I sold it to a local Ford drag racer.