06redzx14
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posted December 11, 2010 05:08 PM
Experimentig with cam degreeing
Can someone explain to me why tdc with the throttle stop is different from the factory mark for tdc.
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06 alien head, no flies, PC+hub, 16/45 44 43, air shifter, dry shot
  
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06redzx14
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posted December 11, 2010 05:32 PM
just read the instructions again on web cam's sight. the number i am getting is not top dead center it is just a reference to indicate that the 0 is correct.
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06 alien head, no flies, PC+hub, 16/45 44 43, air shifter, dry shot
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KZScott
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posted December 11, 2010 09:06 PM
TDC with a POSITIVE stop is actual TDC. the TDC that is indicated by the crank pos rotor/case halves is just close, and can be off by several degrees depending on if the head has been milled, thickness of HG or BG ect ect. the further away from stock you are the further it can be off.
i dont use a pos stop, i put a DI directly down the plug hole
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01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
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dougmeyer
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posted December 13, 2010 03:15 PM
 Edited By: dougmeyer on 13 Dec 2010 23:17
The primary reason is that the positive stop method is the only way to locate the actual point of TDC in crank degrees. This is necessary because of what is referred to as "dwell". When the piston approaches TDC, the vertical motion becomes less and less in the "up" direction until at an imperceptible point, it appears motionless as the crank continues to rotate, and then begins it's downward movement. Think about the big end moving less up and more "sideways" at the top. It actually stops, of course, at the point that it reverses direction, but the piston's movement per degree gets so small that you can't really see it or effectively tell where the "center" is. And, the longer the stroke, the more exaggerated this is.
So, by using the Positive Stop method you are calculating the actual point based on locating it between two very easily identifiable points, those being the stopping points in each direction. TDC is EXACTLY between them. Exactly and always.
Doug
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KZScott
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posted December 13, 2010 07:03 PM
I guess i should point out that using a DI only really works well with hemis or pentroof combuston chambers and only if the piston isnt really "peaky". i find TDC the same way you would find a cam CL on my bike. so much "lift" before and after ( .040) and then go in the middle.
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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kawasakijockey
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Posts: 1876
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posted December 14, 2010 03:59 PM
Scott, it still isnt the best way to do it because of the dwell time Doug has mentioned. The posi stop method is fool proof.
____________
Get on the shortbus boys 'cause its time to get schooled.
2007 ZX-14
1.38 60ft
9.03 @ 149mph
8.95 @153 small shot n2o
8.68 @160mph 5lbs boost
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2000redrocket
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posted December 14, 2010 04:25 PM
scott just hamer out a old sparkplug. thread it for a 6mm longish bolt and put it in and turn it over. i my self would put the tdc mark at the guess tdc and turn the bolt down till it touches and then back the crank up a bit and go one tuen more , take it out and weld the threads and there is a cheep piston stop.
i never checked my bike but the expencive dampener on my dusters 440 is correct on the tdc. but for the money if the crank guy did his job making the key way it should be dam close.
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KZScott
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posted December 14, 2010 05:09 PM
i have a pos stop i made from a plug and a bolt, i just dont like using it. a DI has give incase you sneeze or whatever when moving the piston into the pos stop and hit it instead of just bringing it up to touch.
cams have dwell at max lift, which is why you measure .040 of lift before and after then split the diff. its the same princeple when checking TCD. bring the piston to TDC going by the marks, zero the gauge, spin it over a couple times to verify that its really zero when the piston is up there in the "dwell zone" then check .040 before and after zero. split the diff. if this didnt work we wouldnt be able to time cams.
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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06redzx14
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posted December 14, 2010 05:59 PM
what's the difference in the 0.50 method and the 0.40 method? I used the instructions off the webcams sight
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06 alien head, no flies, PC+hub, 16/45 44 43, air shifter, dry shot
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mathews
Expert Class
Posts: 425
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posted December 14, 2010 06:07 PM
About .010
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2000redrocket
Pro
Posts: 1662
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posted December 14, 2010 07:54 PM
well scott not all cam lobes are not all made with the same amount of lift on the up and down side of the lobe (simectrical lobes). that is the issue on degreeing the cams using one way like you use verses the other way by using the wheel and getting opening and closing numbers (which gives you overlap numbers and can tell you a lot more with the centerline numbers.
the reason you can do it (degree cams )either way is if you do it the same all the time.
then you have cause and effect on your changes.
do not mix it up.
scott i imagin the DI for tdc is with in a degree or so of the true tdc from the cams i have done (which is not near as much at doug or ent i bet). but i have done them and attention to detail is the key. if you do the same thing the same way you are also ok. if you mix the way you get tdc ot centerline it will F up the system you have.
not flaming you scott cause if it works keep doing it. just saying the other side of it.
on the pulling truck we did the centerline by .050 both side of max lift of cam intake lobe. found on the dots was 10 deg the wrong way (retarded, no low end power and top end sucked also)
tshults bike we did open and close after posative stop tdc> i know we are with in .5 of a degree of the number we were after. (his engine had tdc close also but not dead nuts on like my 440.
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KZScott
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posted December 14, 2010 07:58 PM
you could use .080, or .049 or whatever, just make sure you use the same number. you really just need to use a big enough number to get outside of the dwell area.
.040 is basically the metric way about 1mm, .050 is the std way
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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2000redrocket
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posted December 14, 2010 08:04 PM
yes but remember not all lobes are semectrical in shape and the true center coulod be off that way.
keep up the good kaw work. your bike hauls ass
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KZScott
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posted December 14, 2010 08:04 PM
rr, im not sure i follow the overlap method you are refering to?
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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2000redrocket
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posted December 15, 2010 02:54 AM
how long the exhaust is open while the intake is open>
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dougmeyer
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posted December 15, 2010 10:51 AM
Don't get creative on this stuff. There really is only one way to do it right. ALWAYS be very gentle and move slowly. There is an incredible amount of leverage and the force on the stop or anything else is higher than you expect.The only really "danger" to PS TDC finding is if you try and do it with valves and cams installed, wherein you will likely bend the valves as they hit the stop.
Don't laugh, it's been done.
Asymmetrical lobes don't matter because the the lobe center is defined by the crank degrees before and after the max lift point. An asymmetrical lobe moves the lobe center and the result is accurate in crank degrees.
In other words, don't alter your technique. Just always use the same checking lift.
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kawasakijockey
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posted December 15, 2010 11:54 AM
quote:
There is an incredible amount of leverage and the force on the stop or anything else is higher than you expect.The only really "danger" to PS TDC finding is if you try and do it with valves and cams installed, wherein you will likely bend the valves as they hit the stop.
Don't laugh, it's been done.
That is why I have done it with the head off when building an engine. With the head on I took the cams out.
____________
Get on the shortbus boys 'cause its time to get schooled.
2007 ZX-14
1.38 60ft
9.03 @ 149mph
8.95 @153 small shot n2o
8.68 @160mph 5lbs boost
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entropy
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posted December 16, 2010 04:50 AM
quote:
.The only really "danger" to PS TDC finding is if you try and do it with valves and cams installed, wherein you will likely bend the valves as they hit the stop.
Don't laugh, it's been done.
Doug,
I ALWAYS use my positive stop on an assembled motor.
I assemble the motor, put the cams on, and GENTLY rotate the motor to assure i am not a tooth off.
Then i set lash
Then i use a positive stop to zero my degree wheel.
Then i set cams/PTV
Got the Busa motor to rotate with cams on last night, will set up lash/CL's/PTV this weekend.
Am I miisunderstanding something here?
(wouldn't be the 1st time)
Karl
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osti33
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posted December 16, 2010 01:46 PM
Edited By: osti33 on 16 Dec 2010 21:46
quote:
quote:
.The only really "danger" to PS TDC finding is if you try and do it with valves and cams installed, wherein you will likely bend the valves as they hit the stop.
Don't laugh, it's been done.
Doug,
I ALWAYS use my positive stop on an assembled motor.
I assemble the motor, put the cams on, and GENTLY rotate the motor to assure i am not a tooth off.
Then i set lash
Then i use a positive stop to zero my degree wheel.
Then i set cams/PTV
Got the Busa motor to rotate with cams on last night, will set up lash/CL's/PTV this weekend.
Am I miisunderstanding something here?
(wouldn't be the 1st time)
Karl
I think what Doug is saying here Karl is that if you have a cam off a tooth or 180 degrees or whatever and use your positive stop you can run a valve(s) into your positive stop and bend the valve.
It's been done. I've seen a few get bent that way.
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2000redrocket
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posted December 16, 2010 05:41 PM
i can see that if you have the stop down like mad but we went to tdc mark and hit the piston backed the engine up and turned down just a bit more. sofar not hit valves. though we are carefull like ent says.
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gs11ezrydr
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posted December 16, 2010 07:03 PM
Well as far as( Experimenting) with cam degreeing before I knew much about it I turned the cams to where I got the highest cranking compression I believe about 310-320 p.s.i. checked PTV clearance and went to the track.I thought man this is gonna be good and the bike fell completly on it's face I mean dead nothin sick whew!.Set it back to the base line and got it back. I was wondering if any one could explain just what happened to make it run so bad with such high cranking compression.I had it explained but really didn't get it.Never tried it again and was embarassed to mention it I was so stupid.
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dougmeyer
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posted December 16, 2010 07:06 PM
Karl,
I shouldn't have used the word likely. IF you are working with a combination you know well, it's not likely, or maybe even possible to hit the stop with the valves. BUT if you're building something for the first time, maybe bigger valves, a new cam grind, you're in a tooth off, whatever. you need to be careful. You work on a very specific type of engine, there are many designs (Hemis come to mind, right Scott?) where the valves will absolutely hit the stop. It has happened to me. When I write stuff I try and be cautionary for those that might not have any experience.
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It's not that I think you're dumb, it's just that so much of what you know isn't true....
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2000redrocket
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posted December 16, 2010 07:09 PM
Edited By: 2000redrocket on 17 Dec 2010 03:12
the intake cam had to be advanced a lot so the valve was closed before the piston went up at all , that was probally just bad top end numbers,
did it feel good and snappy in the lower rpm zone or just bad all around?
doug i bet a hemi could hit
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gs11ezrydr
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posted December 16, 2010 07:31 PM
Yea throttle response was killer, and the short times were real good.But just wouldn't rev out or pull up high.After going back to base line and then playing around with the exhaust timing a few degrees at a time got it where it would fly.169.89 m.p.h and left them alone.Now just bump a few degrees at a time to compensate for various track conditions.
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Y2KZX12R
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posted December 18, 2010 04:50 AM
quote:
Well as far as( Experimenting) with cam degreeing before I knew much about it I turned the cams to where I got the highest cranking compression I believe about 310-320 p.s.i. checked PTV clearance and went to the track.I thought man this is gonna be good and the bike fell completely on it's face I mean dead nothin sick whew!.Set it back to the base line and got it back. I was wondering if any one could explain just what happened to make it run so bad with such high cranking compression.I had it explained but really didn't get it.Never tried it again and was embarassed to mention it I was so stupid.
That's a good lesson in valve timing overlap. As a general rule advancing the intake cam gives the engine more lower and mid range power. And advancing the exhaust cam gives the engine more top end power.
In these engines we have the ability to control the timing of each cam thus controlling the lobe separation angle. On a single cam engine the lobe separation angle is ground into the cam.
So by controlling the lobe separation angle you can control the timing of the neg pressure waves introduction to the combustion chamber and intake port.
The exhaust pulse is critical in getting the chamber pressure lowered which starts the intake flow moving sooner because the intake valves are also open.
The exhaust actually pulls some of the fresh A/F charge out while doing this, and at lower rpms with a lot of overlap, this can hurt low and mid rpm power. Without variable cam timing you have to pick what you want.
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Y2KZX12R
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