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  1. #1
    just GOT TO DO IT! great lakes gpr 1200's Avatar
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    max head torque?

    I have a book, but I was wondering What do you guys torque your head down to? What is max? the last thing I want to do is break a bolt or strip a hole.
    What Is a good squish for a 1390 GK? I have a reading of .041 . how does that compare to everyones?
    I am at 145 psi comprestion? how does that sound? Please chime in....
    Does any one know what the cone size is on a 2004, compared to a 2002? Is the 04 a bigger size or smaller? bigger is better for top speed right? any help on these questions would be cool.... Thanks


  2. #2

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    16 ft lbs all around 2 times, then a final at 26 ft lbs.
    Hey, a quick question, just finished bolting down my 1390 GK head, and I noticed the head gasket was practically perfect the size of the bore. How did you be sure it stayed centered when putting the head down, as there is a bit of room around the bolts for the gasket and head to shift. Thought about making a couple of cut off bolts, epoxy or weld up the od around the gasket area, then turn down to perfectly fit the bolt holes in the gasket and head. That would keep the gasket centered perfectly until you tightened a couple of head bolts, then remove the cut down ones. Did you use the 3-bond to seal the head gasket?
    What cone do you mean? The pump cone is the same until the 05 pump came out, which is a different cone all together.

  3. #3
    just GOT TO DO IT! great lakes gpr 1200's Avatar
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    The gasket is bored to fit the bigger pistons. I have had mine apart a few times never had any problems with getting the gasket centered.
    I was refering to the rear pump cone. are they all the same size (exit hole)? or is the 04 a differnt size than the 02?

  4. #4
    Happily Self-Employed WFO's Avatar
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    Quote Originally Posted by great lakes gpr 1200 View Post
    The gasket is bored to fit the bigger pistons. I have had mine apart a few times never had any problems with getting the gasket centered.
    I was refering to the rear pump cone. are they all the same size (exit hole)? or is the 04 a differnt size than the 02?
    No need to overtorque the bolts. The stock torque is fine. Unless you are using stainless bolts. On the SS headbolts, I torque them to 18flbs.

    Yes there is a little room to move the head around. The only way to know for sure if its centered is to check the squish. If its more on one side than the other, losten the head and re-center till you get an even number both sides.

    Me and Duke talked about designing a way to make sure the heads are perfectly centered. Hopefully more to come on that.

    If you are talking about the exit nozzle, yes the 02 comes with a larger opening (87mm) than the 04 (85mm). Usually the 85mm will produce more top speed, especially with the newer style HO pump.

  5. #5

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    Quote Originally Posted by WFO View Post
    Yes there is a little room to move the head around. The only way to know for sure if its centered is to check the squish. If its more on one side than the other, losten the head and re-center till you get an even number both sides.

    Me and Duke talked about designing a way to make sure the heads are perfectly centered. Hopefully more to come on that.
    I was more worried about centering the head gasket, as its a big bore and has not much extra clearance to the bore.

    I did find a good solution: I took 3- 8mm x1.25 hex socket head bolts 3/4" long, and turned down the socket head to .332, which is just a couple of thousands under the head gasket hole size. Put these in each end head bolt hole in the block and tighten till shoulder touches block, and one on the opposite side in 1 or 3 cyl. This holds the head gasket perfectly centered, as well as the head. Install the center cyl head bolts, tighten to the first torque spec, and then use an allen wrench to remove the 3 locating socket head bolts(might use a spot of tape on the end of the allen wrench to make it tight enough to pull the loose bolt out of the hole). Voila, centered head and gasket.

  6. #6
    just GOT TO DO IT! great lakes gpr 1200's Avatar
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    Quote Originally Posted by WFO View Post
    No need to overtorque the bolts. The stock torque is fine. Unless you are using stainless bolts. On the SS headbolts, I torque them to 18flbs.


    If you are talking about the exit nozzle, yes the 02 comes with a larger opening (87mm) than the 04 (85mm). Usually the 85mm will produce more top speed, especially with the newer style HO pump.

    KOOl That's what I was after. I am going to put my 04 cone on my 02 pump also. every little bit helps !!

    I just added some reeds VF-3s and spacer, key way and some hull work. I am looking at a rxp that smoked me last year......

    and he should have... he had a heck of alot more MONEY than I did in his...my guess is about $4000.00 plus ski cost, I am not sure but he had the intercooler and all kinds of she-doo stuff changed. he got me by two MPH....
    so it is ON!!

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