Z-11 and Mystery Motor Camshafts

rstreet

Well Known Member
Supporting Member 17
The late 64 and 65 400 and up 409 were supposed to be the same cam as the 63 Z-11 hence the 583 heads.The "Resto" grinds are different,some more than others .

Don back “in the day” we ran allot of blue printed cams. TRW being the most known but later all the cam companies had them I think. Usually these sounded different and ran a bit better at the track as I recall. I recall later Isky came out with something in the 70’s but don’t recall the number. I put several in 396’s for people who seemed pleased
Robert
 

rstreet

Well Known Member
Supporting Member 17
Another “trick” cam was the Mercruiser HO hydraulic cam but..... only one or two figured out keeping the rpm’s less than 6,000.
Robert
 

Don Jacks

Well Seasoned Member
Supporting Member 3
That Mercruser cam was the same cam that was in the 65 z-16 Chevelles and was a really good upgrade for any hyd.cam equipped rat for street or mild street/ bracket use.I installed one for a buddy not telling him what it was.He terrised the local guys for a while then the next thing I know I had 4-5 guys wanting for me to do the same for their motors.It became the "Baseline" cam for big blocks much like the L79 cam was for the small blocks back in the day.
 

Murphdog

Well Known Member
Supporting Member 2
Nice Pat! Now if I only had one of those 62 Corvette pry your wheel off bars I’d be set too:wacko:dohView attachment 87076View attachment 87077
Was browsing old post's and saw this. My parents bought a new 66 Impala from Jack White in Perry. That's where we were from. 283, powerglide. I inherited in 1974 as my "1st set of wheels". It would hit 100 going down hill into the Raymond Erb bottom!
Not sure what's going on, was quoting Tooth's post from page 1 with the pic of the Jack White yardstick.
Jeff
 

Greg Reimer

Well Known Member
One of the things they don't advertise is that the cam installed in the motor may have the same advertised lift and duration as the catalog says, but the cam the race teams got was far different. If you made a graph and profiled a given cam lobe, say, #1 intake and exhaust valves, you would find some real surprises. The lift may start at the same place on the degree wheel, and the maximum lift may be at the same point, but the rate of lift on the race only cam is way different with the duration at .050" being way more.The cam profile in a cam like an NHRA Stock Eliminator engine may have the exact OEM lift specs, but the actual duration at .050" on up to max lift is way more. The limiting factor for a lot of Stock and Super Stock motors is the piston to valve clearance at .050" lift or so. These cams have a very brutal series of valve events between those two points, and it is not uncommon to have small block Chevy motors with valve spring pressures of 200 PSI on the seat with 400 PSI at maximum lift. That's what is necessary to control valve float and valve bounce when it closes. Another thing, a cam that is ground to be optimal for a Z-11 might not fit a 409 without piston to valve clearance issues because the longer stroke crank moves the piston a bit sooner and a bit faster away from both TDC and BDC. The fact is that the 2nd design 409 hi po cam was designed for the second design head with the taller springs and the deeper spring seats just for that reason. The #583 cam might say it's for a Z-11 and the factory second design 409 heads, but in actuality it was only a standard replacement cam and not very optimal. It would be nice to find an OEM Z-ll cam and install it in an engine, set up an accurate valve profile measuring device, and compare degrees of actual duration with a 7735 service replacement cam. They probably wouldn't be any where close. Another air flow enhancer for an engine with valve port size restrictions is the profile of the back of the valve. OEM valves tend to be rather thick and heavy for longevity reasons, where true race only valves would flow significantly more air. My NHRA legal 327/250 horse '68 Chevelle motor has .390" intake lift and .410 exhaust valve lift but it sounds like a jackhammer breaking concrete when it is running because the heads and intake were rather carefully matched to it to take advantage of the rules any way we could. It is funny to fire it up and drive to the lanes or back on the return road after making a run because it is quite loud for 9:1 actual compression. The valve train wouldn't last too long on the street, however. If I took the blueprinted NHRA stocker cam out and put in an OEM replacement cam meant for Grandma's Caprice, the engine would idle at 500 RPM in drive, lay down just past 5000 rpm, and would make about 265 horse power at 4800 RPM. Can't have it all, that's for sure.
 
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