Hi,
I am looking for spec info on GPZ1100A2 unitrack (1984) camshafts, part number12044-1057. I am looking for the valve timing quoted in the spec (BTDC, ABDC etc), the duration and the Cam heights. I am in process of rebuilding a 1982 Z1000J2 which already has an 1105cc Wisco kit on it and am thinking of fitting the GPZ cams. Any help appreciated.
Matt
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Spec info reqd on GPZ1100 cams
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ZX1100-A1 valve timing:
Inlet Open 40 degrees BTDC
Close 80 degrees ABDC
Duration 300 degrees
Exhaust Open 80 degrees BBDC
Close 40 degrees ATDC
Duration 300 degrees
The ZX uni-trak head also has different shaped combustion chambers to the 1000J head,the ZX head also has shim under bucket cam followers.
Probably a good idea to have a word with Ray or Steve at Debbens,01425 474628.
Inlet Open 40 degrees BTDC
Close 80 degrees ABDC
Duration 300 degrees
Exhaust Open 80 degrees BBDC
Close 40 degrees ATDC
Duration 300 degrees
The ZX uni-trak head also has different shaped combustion chambers to the 1000J head,the ZX head also has shim under bucket cam followers.
Probably a good idea to have a word with Ray or Steve at Debbens,01425 474628.
Jack
Nice one Jack
The GpZ cams are about 1mm higher lift. You need to clearance the head to allow them to rotate. 16 x 1mm grinds with a belt sander!
So its head off and not a straight drop in.
Shim on top might be a problem too as they can flick the shim off the top of the bucket if you go very very radical. Not that that is what you mean i guess.
You'll only get a small improvement in performance with just the cams alone but that said its a fairly painless way to up the output.
You can use the cam timing marks on the existing cam wheels as a guide for timing or dial them in using a sensible lobe centre value.
Standard cam wheels should be sufficient but ultimately you may find that you want the flexibility of adjustable cam wheels.
A neutral value would be 108 in and 109 out.
Lobe centre method does away with duration and timing values and allows a direct (and measurable )method for setting up and future tuning.
If your going to use the later GpZ head (unitrack) you need to get the crowns of the pistons profiled. Not necessary with the early GpZ head i believe.
Late head has 'stood up' valves on the exhaust side.
Dialling in cams is not as terrifying as it sounds.
Take a look at Piggy's project Lawson it has much of the info there and some good pictures around this topic and beyond.
Computer just gone on the fritz so will have to leave this for now.
AL
The GpZ cams are about 1mm higher lift. You need to clearance the head to allow them to rotate. 16 x 1mm grinds with a belt sander!
So its head off and not a straight drop in.
Shim on top might be a problem too as they can flick the shim off the top of the bucket if you go very very radical. Not that that is what you mean i guess.
You'll only get a small improvement in performance with just the cams alone but that said its a fairly painless way to up the output.
You can use the cam timing marks on the existing cam wheels as a guide for timing or dial them in using a sensible lobe centre value.
Standard cam wheels should be sufficient but ultimately you may find that you want the flexibility of adjustable cam wheels.
A neutral value would be 108 in and 109 out.
Lobe centre method does away with duration and timing values and allows a direct (and measurable )method for setting up and future tuning.
If your going to use the later GpZ head (unitrack) you need to get the crowns of the pistons profiled. Not necessary with the early GpZ head i believe.
Late head has 'stood up' valves on the exhaust side.
Dialling in cams is not as terrifying as it sounds.
Take a look at Piggy's project Lawson it has much of the info there and some good pictures around this topic and beyond.
Computer just gone on the fritz so will have to leave this for now.
AL
Last edited by Al on Sun Jun 07, 2009 10:59 am, edited 1 time in total.
Hit the F key by mistake and it all got a bit exciting.
Piggy's project here
http://www.z1ownersclub.co.uk/forum/vie ... php?t=5882
Do a forum search for GpZ head etc. Some very usefull stuff in the archive which will shine a big light on this topic. Can get very expensive as its unlikely you'll be able to stop yourself at just cams!!!
AL
Piggy's project here
http://www.z1ownersclub.co.uk/forum/vie ... php?t=5882
Do a forum search for GpZ head etc. Some very usefull stuff in the archive which will shine a big light on this topic. Can get very expensive as its unlikely you'll be able to stop yourself at just cams!!!
AL
Thanks Al & Jack, very useful.
I have motor stripped to component molecules at present. Just delivered crank to SEP Kegworth to get it checked, straightened, welded etc. I had the head gas flowed when I added the 1105cc kit in 1991 by a tuning "expert" in Kent who shall remain nameless. When I took it apart recently I found they had used the standard head gasket £$%^&* and the inlet / exhaust cams were in the wrong way around...doh! I "was" planning to use the existing J2 head and to put in bigger inlet valves, shim under bucket and to get more port work done. Clearly the bigger valves, more lift of the GPZ cams and the 10.25:1 comp ratio means the head / piston clearance needs some work...I will look into this further to decide whether it might be best to just go for a ZX head and be done with it. I have been talking to a Graham Salter of Diptune (Yorkshire) who I have in mind to do the top end work. He reckons that with the above + Mikuni 33mm smoothbores I should get an easy 110bhp at rear wheel...perhaps 120bhp, although I have bought a new Vance & Hines system which might have been a mistake. Ever onwards.....
I have motor stripped to component molecules at present. Just delivered crank to SEP Kegworth to get it checked, straightened, welded etc. I had the head gas flowed when I added the 1105cc kit in 1991 by a tuning "expert" in Kent who shall remain nameless. When I took it apart recently I found they had used the standard head gasket £$%^&* and the inlet / exhaust cams were in the wrong way around...doh! I "was" planning to use the existing J2 head and to put in bigger inlet valves, shim under bucket and to get more port work done. Clearly the bigger valves, more lift of the GPZ cams and the 10.25:1 comp ratio means the head / piston clearance needs some work...I will look into this further to decide whether it might be best to just go for a ZX head and be done with it. I have been talking to a Graham Salter of Diptune (Yorkshire) who I have in mind to do the top end work. He reckons that with the above + Mikuni 33mm smoothbores I should get an easy 110bhp at rear wheel...perhaps 120bhp, although I have bought a new Vance & Hines system which might have been a mistake. Ever onwards.....
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