Z-11 Cam Profile?

[SS425HP]

Cam Timing

Had the same thing with a Cloyes set. Put it in straight up, numbers were off. Retarded it 4 degrees, and numbers were right on. That's the value of checking cam timing. Had me going in circles for a while. Kept thinking I was doing something wrong. After checking it enough times, and doing an intake center line, I decided I was right and put it in on the retard keyway. Seems to work fine, now.

Fred

 

[jim_ss409]

Nuts, Your Z-33 cam has the same duration at .050 as the Z-11 cam but it has a much narrower lobe separation angle. It's LSA is 110 degrees while ths Z-11 cam has a 113.5 deg. LSA. The narower LSA means that there is more overlap time. The overlap time is the time when the intake and exhaust valve are both open at the same time. The exhaust isn't done shutting when the intake is starting to open. This overlap time works especially well on cars with headers because the outgoing exhaust will actually suck on the incoming air-fuel mixture during the overlap period and boost power. But, at an idle, when the exhaust isn't moving well the exhaust fumes tend to get pushed back through the intake valve into the intake manifold. So, cams with narrow LSA's tend to give you a rough idle and low vacuume. The Z-33 cam is a pretty big cam for 409 cubic inches. It will of course work but your carb. and ignition tuning will have to be right on and even then I doubt you'll ever have enough vacuume to comfortably run power brakes. I think Curt Harvey used to recomend the Z-33 for strokers and the Z-45 for stock displacement 409's. The Z-45 also has a 110deg. LSA but it only has 240deg. duration where the Z-33 has 250deg. I can't remember if you are running the stock displacement, 409ci. If you are it'll be hard to get the car to run well on the street with that cam.

 

[Nuts]

Excellent Information !!!

Jim,

Thanks for the excellent information and description of the cam and performance. I'm kind of dumb on how all this stuff works to make it go fast. What do you recommend for initial timing with the Z33 cam ?

 

[jim_ss409]

Without knowing how much centrifical advance is built into your distributor that's a hard question to answer. With a big cam you want lots of initial timing but if you go much beyond 16 degrees of initial advance it might be hard to start. I think that 15 degrees initial advance with another 20-21 degrees of centrifical advance would be about right. That would give you about 35 or 36 degrees total. You would also want all of the centrifical advance in by about 3,000 rpm. If you've got a dial back timing light I'd set the total timing at about 35 degrees. Depending on what springs are in the advance mechanism you might have to rev it pretty high to check the total advance. If the timing hasn't stoped advancing by the time you hit 3,200 you'll want to install lighter springs (they're under the rotor) so that the advance is all in by about 2,800 to 3,000rpm. Set it at about 35deg. Then let it idle and see what you've got for initial timing. If it falls between about 12 to 17 degrees that should do it. If it comes out at less you'll want to limit the amout of centrifical advance and if it's more than about 18 degrees it might be hard to crank over, especially on a hot day. A distributor with vacuume advance also helps smooth out the idle, if you've got enough vacuume to make it operate. You should always check the timing with the vacuume hose disconected and pluged. When you hook it back up the idle will speed up and smooth out. That's because the engine really needs lots of timing advance at an idle to run it's best. Aparently an engine with big heads and a big cam needs lots of initial timing because the air-fuel mixture is moving slowly, is not well mixed and is contaminated by exhaust gasses that get pushed back up the intake ports. This poorly mixed and contaminated mixture needs to be ignited sooner. Therefore more initial advance. By the way more initial timing will raise you vacuume just a bit.

 

[Nuts]

Thanks - Great Information

Jim,

Thanks for the detailed and helpful information. I checked the advance out today and it appears I've got 34 degrees of total advance. I didn't have a tach, but picked one up today and will install and check out the rest of your thoughts. The RPMs seemed pretty high, but without the tach it's hard to say when the advance was reached. I'll get back with an update ASAP.

I also set the initial advance at 13-14, it seemed to help the motor run alittle smoother at idale. Don't know if has helped the "running hot" issue, because I didn't drive it vary far, just around the block. Still have an oil leak from the pan area I've not sorted out and I hate to drive it very far. Just makes a mess of the whole underside of the car.

Thanks again for your detailed post, it was very helpful....

 

[Skip FIx]

My old Crane F-Nitro 310/320 .580/.590 was a pretty good thumper in my old 409. Not much bottom end but at 2500 came on hard and propelled my 64 to 12.20s @ 108 in Dallas in 1972 with 425 top end on a stock 340 hp short block.

I had another 09 with the Z11 cam that sounded pretty darn lumpy also.

I think looking at the Ultradyne(handled by Lunati or Bullet now) or new Comp XE lobes have the best technology for a flat tappet street/strip out there now.

 

[Wild Bill Burge]

Original Z-11 cam

Hey guys...reading some of your Z-11 cam numbers jogged my memory, just a little, as I'm 62 and well...Anyway, in '63 at age 19, I bought for my bench seat Impala an over the counter Z-11 cam. aluminum fan shroud at $9.00 a side, aluminum water pump that leaked and front bumper. But of course my parts counter and use to be good friend got fired for his efferts. And maybe selling me it all at wholesale! The only options besides the 425 engine was power brakes and an AM radio. About that vacumn with the Z-11 cam... yeah, not a whole lot and a
lot less then with the 425 cam. No low end torque so had to spin the engine with 456's....about 7 sets to be exact. I still have that original cam and Oh yeah, a #7 piston with intake valve stuck through it...somewhere! Wonder where that $18 shroud is?

Wild Bill Burge
"The Living Legend Z-11

 

[skipxt4]

Z-11 Cam

I still have my Z-11 cam from the sixties. (not using it though) I agree with all comments regarding no, low end torque. But after the engine hit 3000, hang on. I installed a power brake booster, but the brake pedal was always hard. I can still recall my engine burning my eye's, while idleing and fouling the plugs, if I didn't pound the crap out of it, everyday. It definately wasn't a street friendly cam. If I didn't burn Sunoco 260, my car would buck me around, like I was on a buckin bronco. Like Jim and Aubrey said, cam technology has come a long way, since the sixties. This time around, I'll be using an Isky. The Z-11 cam will just be a memory, from my previous life. Skip