Cams in stock KZ1000 head...

Anyone know how much lift you can run in a "stock" head before you have to start modifying parts? My understanding is that a stock KZ1000 head can flow enough for up to about .370 lift before the ports become the choke point. But how much lift can be run before the guides are a problem, you have to cut the bucket holes so cams can clear, retainers start hitting the guides? Springs used will determine when spring bind might occur. What lift before you need to go to SOB valve gear? Not worried about piston/valve clearance as most who go this route will have gone to aftermarket pistons with bigger valve pockets but if you know, go ahead and mention it so we will have that info also. Any opinions/knowledge about these and others you might think of I misses?

Tappet bore clearance comes into play long before the guide becomes an issue. A .385" lift Z2 cam motion grind is about max without having to clearance the tappet bores.

There are exceptions though. The base circle size can allow for cams of up to .400" lift to be used but you have to order them with a small base circle.

Anything over .400" lift, it's advisable to install shorter guides.

I've had some of the new cores from Web where the sprocket boss is thicker and required some grinding to prevent it from rubbing the cam chain tunnel. Just another thing to be aware of.

J heads are a bit different story.

A great all around cam is the Web 118 grind for the old KZ motors. Also the Z2 from CM.

Probably the best answer you're gonna get right there racer. Go ahead now Larry, toot your own horn.

AS far as SOB setup. 410 is the safest you can go without having to change. We used to sell a 418 lift, and while degreeing a set in, a builder wondered what the clicking sound was. He then noticed that as the lobe came around it would push the shim down into the groove on the bucket causing the other side to pop up, then as the lobe went further it snapped the shim back down. People ran those with shim on top, but needless to say, it was like playing Russian roulette

What are good cam degree numbers? No idea what stock should be at...110*? Any suggestions for other cam grinds...Z2...3X...119...etc.? Do bigger cams require different igniton advance settings...I'm talking street cams here. What does advancing or retarding intake and/or exhaust cams do for the power curve and does igniton timing need to be retarded or advanced?

racer54 wrote: What are good cam degree numbers? No idea what stock should be at...110*? Any suggestions for other cam grinds...Z2...3X...119...etc.? Do bigger cams require different igniton advance settings...I'm talking street cams here. What does advancing or retarding intake and/or exhaust cams do for the power curve and does igniton timing need to be retarded or advanced?

You can't compare cams like that. Those 3 grinds have very different characteristics. When in doubt, put them on 110 centers..... 'nuff said. If I start explaining why this or why that...someone will probably take that to be "tooting my horn"

OVER AND OUTTA HERE :dry:

Figured so much. I'm just trying to gather some information that myself and others can refer to at a later date when something comes up they need to know. To get some of this stuff all in one place. Myself, I like to know this stuff. I know there are many variables to some stuff but not sure what can be considered "set in stone for this combination" type thing. For example...advancing intake cams will give more bottom end. Right? This sort of thing. Always looking for information that might come in handy someday and figured I'd pick some brains.

racer54 wrote: Figured so much. I'm just trying to gather some information that myself and others can refer to at a later date when something comes up they need to know. To get some of this stuff all in one place. Myself, I like to know this stuff. I know there are many variables to some stuff but not sure what can be considered "set in stone for this combination" type thing. For example...advancing intake cams will give more bottom end. Right? This sort of thing. Always looking for information that might come in handy someday and figured I'd pick some brains.

Well...funny you mention that. Hemi heads are a different animal than a wedge head and overlap lift is a double edge sword. A colleague in the same type of business did some extensive dyno testing on a Chrysler hemi head race engine.

On their Superflow Dyno, the Ve was over 140% :ohmy: He thought his Dyno was misreading. NOPE...it was correct and verified. Here's the kicker...

Spreading centers to 118/120 dropped Ve back to he mid 120's but picked up over 50HP and the car ran much quicker at the track. Reason being was over scavenging during he overlap event. [fresh charge going right out the exhaust valve].

Curing that by push the centers up picked up torque through the range because more charge was trapped an burned.

Mind you that was a serious engine with serious cam.

Only Andrews and Megacycle ever gave / give cam specs that are worth a dam to an engine builder or tuner. Go grab a Megacycle cam sheet for KZ's and see for yourself. Megacycle really put an effort into making good information available. They give overlap lifts on different centers for a number of their KZ cams. Really allows a guy to make enlightened decisions during the design process of the build

Is that the reason on cams for turbo/blower engines that duration and/or overlap is kept shorter to keep the charge in the cylinder and not have the pressure blow it through the head without being used? Assuming advancing the intake gives more bottom end is right, then would retarding the intake move it towards the top of the rpm range? Or would that be handled by retarding the exhaust cam? In either case whichever is right, do you retard both cams or just one side?

racer54 wrote: Is that the reason on cams for turbo/blower engines that duration and/or overlap is kept shorter to keep the charge in the cylinder and not have the pressure blow it through the head without being used? Assuming advancing the intake gives more bottom end is right, then would retarding the intake move it towards the top of the rpm range? Or would that be handled by retarding the exhaust cam? In either case whichever is right, do you retard both cams or just one side?

There are just too many variables to make a generalized statement on that with accuracy that will cover every conceivable engine build. Web & Cam Motion have articles on their sites that give good explanations of overall cam timing scenarios.

A turbo engine is low compression to start with. If you put long duration cams in it, one of the effects would be to weaken it's performance when it's off boost.

An easy way to tell if you're cam timing on a hemi head engine is hurting you is to run it and then pull the pipe to look for fuel trails in the exhaust ports. If they are in fact there, something needs to be addressed because it's over scavenging the cylinder [fresh charge wasted out the exhaust].

The more overlap in the timing, the more likely that scenario can occur.

Never forget that events run concurrent in the engine. Exhaust and intake cycles share time & space. What one likes the other doesn't know or care about

Who sells cam motion Z2 cams?

cam motion is out of the motorcycle cam grinding business :dry: ......... web makes the 119 grind which is a "drop in" like the Z2... :blink: