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  1. #1

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    Valve train information

    Ive been searching around here but haven't really found the info I want. I wanted to know what years and what was improved on the 4-tech valve train. I have a 2003 GTX that I eventually want to push rpm wise. I already know about swapping to the forged pistons but I am curious as to what I should be looking for valve train wise. Springs, rocker assemblies, valves. Any info would be greatly appreciated. I know I see people selling all sorts of parts here. I just don't know what I am looking for. I know they were bound to be improvements over the 7600 rpm limit which in time I planned to go over. Thanks in advance.


  2. #2
    JT jpt7779's Avatar
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    The stock valve train is good to 8500 rpm without springs and retainers upgrade. The problem with the little GTX 185 is the cast pistons, 38# injectors, SC gear ratio, no IC, and small diameter pump which is why it is limited to 7650.

    Read this thread: http://www.greenhulk.net/forums/show...ight=185+build

    Jeremy, did it and poured lots of time, effort and $$$$ in to it and did a great job.

    IMO, there are so many things that need to be done to rev that engine to say 8300, that it is not worth it $$$$ wise. If you are really into wrenching and want to take on a long term project and have lots of patience - go for it!

    Look at my signature for my 2005 GTX.


  3. #3

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    Quote Originally Posted by jpt7779 View Post
    The stock valve train is good to 8500 rpm without springs and retainers upgrade. The problem with the little GTX 185 is the cast pistons, 38# injectors, SC gear ratio, no IC, and small diameter pump which is why it is limited to 7650.

    Read this thread: http://www.greenhulk.net/forums/show...ight=185+build

    Jeremy, did it and poured lots of time, effort and $$$$ in to it and did a great job.

    IMO, there are so many things that need to be done to rev that engine to say 8300, that it is not worth it $$$$ wise. If you are really into wrenching and want to take on a long term project and have lots of patience - go for it!

    Look at my signature for my 2005 GTX.

    Thanks JT. Got an idea of where I want to go. Ive read through Jeremys thread a few times but it is so long and strung out and he changed so many things that its hard to follow.. I have spoken with Jeremy and he has given me some good advise but I was wondering if the valve train needed any upgrading. Already plan to change to forged pistons. I like my GTX, its in very good condition. Ive already done a few things to it including a new aluminum pump housing with a stainless steel wear ring and a 13/20r solas impeller. Kanaflex intake, Riva thermostat upgrade. Ive got a flywheel from a 2004 RXP and plan on upgrading the charger and add an intercooler along with bigger injectors, different ECU a rrfpr. I guess I am looking for a long term project, just something to keep me busy over the winter.. I wished I had went ahead an upgraded the drive shaft and pump but I done all that before I had a chance to sit down and study what I needed to do. I have no complaints as of now but a little more speed never hurt. I would say hands down the mod that made the most change was undoubtly the Riva racing sponsons. Its crazy just how much of a difference those made.

  4. #4
    JT jpt7779's Avatar
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    Sounds like you have this figured out pretty good. Back to your original question, Jerry and others told me this: stock valve train good to 8300-8400, 8300-8500 should at least use retainers, 8500-8800 should use springs and retainers, 8800+ should use lighter valves. I have also seen several guys running 9200 with just springs and retainers with stock valves, so it seems to be a lot of opinion depending on supporting mods.

    Did Jeremy give you any advice about top rpm and or top speed? I would be concerned about going too fast and getting into a stuffing scenario with the small pump tunnel and smaller pump.

    My wife has forbidden me to touch her ski anymore!

    This will be a fun winter project.

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