1000J Head

I would really like to fine a newer 1000J head as I'm using almost minimum shims on the exhaust side with the valve tips ground down.  The retainers do not appear to be ground off.  I bought new 33mm valves put putting them in without grinding a new seat,  then measuring the inserted length shows no improvement over the stock valves.  Will the later police heads work and how late a year can I look for?  Is there anyone in the US who I could trust putting in new valve seats?

The “P” was made from 82-2005 it is rated at 92hp (same as a Ltd so softer cams than a “J”) although all are “J” series 

Any 998/1089 J/GPZ head will do the job EXCEPT the GPZ1100 Unitrack and some Z1100 that have the Bathtub combustion chamber with steeper exhaust valve angle which are not immediately compatible with your pistons without modifications.
You can however in shim on top configurations skim a further 1mm from the existing valve stems, collets and retainers to regain the lost clearance and allow the use of shims in the upper end of the range which will give plenty of scope for future adjustment.
I have done this hundreds of times.
This pic is of the last set i did for my own J head that is on my Racecrafters build.

Rob how do you hold these to skim ? (My seats are being cut currently and the valves ground)

I fit the collets and retainers to a spare valve stem so that it can be held in the lathe chuck and then use the tailstock center to push the valve stem tight into the collets and retainer against the chuck jaws before tightening the chuck.
I have a pre shortened stem and collets for cutting the retainers and another retainer skimmed back around 2mm for trimming the collets so that they can be cut shorter and sit below the surface of the 1mm skimmed retainers..

Thank you all for your help.  I thought that I could only skim only .3mm from the retainer et al.  I will be seeing a machinist this week and will ask him about this.  I have spare collets and valves, but not retainers. I will keep an eye out for a "P" head.

 

MJinCO wrote:

Thank you all for your help.  I thought that I could only skim only .3mm from the retainer et al.  I will be seeing a machinist this week and will ask him about this.  I have spare collets and valves, but not retainers. I will keep an eye out for a "P" head.





 

By the book you can only remove .30mm from the stem because you risk the bucket riding on the collets or retainers.
You can remove up to 1mm (depending on your current stem height) from the collets and retainers to enable a further 1mm to be removed from the tip which will put the stem height back to stock and allow the use of shims in the 300 range.
There is no "book" that will tell you this as it is a modification that goes beyond the normal factory service procedure.
Modifying the collets and retainers does not prevent them from being used with stock uncut valves.
Your machinist will need the head. a 37.2mm stem height gauge ( easily made from a bit of ally bar or brass etc see pic below ) and vernier to measure the protrusion and calculate how much each individual valve can be shortened..
The height gauge is much more accurate and consistent than measuring down the bucket bore with a vernier and make sure it is used against the bare head with the steel spring seat removed.
Any valve lapping or seat recutting should be done before trimming the valves and ideally you should fit 1mm valve spring shims afterwards to retain correct seat pressure.