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Engine basics => Engine set up tips => Topic started by: Matt Piatkowski on October 13, 2016, 07:33:40 AM

Title: ST60 NVA internal geometry
Post by: Matt Piatkowski on October 13, 2016, 07:33:40 AM
Hello,
I am looking for the drawing of the ST60 NVA showing the internal geometry with dimensions.
Specifically, I am trying to understand WHAT stops the needle while it is being rotated CW by hand to the very end.
It feels like hard stop. Maybe it is simply the needle thread hitting the non threaded part of the spray bar hole?
Matt
Title: Re: ST60 NVA internal geometry
Post by: Brett Buck on October 13, 2016, 08:50:32 AM
Hello,
I am looking for the drawing of the ST60 NVA showing the internal geometry with dimensions.
Specifically, I am trying to understand WHAT stops the needle while it is being rotated CW by hand to the very end.
It feels like hard stop. Maybe it is simply the needle thread hitting the non threaded part of the spray bar hole?
Matt

   It's the needle seating itself in the orfice.

   Brett
Title: Re: ST60 NVA internal geometry
Post by: Steve Helmick on October 16, 2016, 03:55:10 PM
I would expect that the orfice would be formed by the point of the tap drill. I guess if you want to split one down the center, you could confirm that. Perhaps grind or file away to the centerline or close? No, I wouldn't bother.

However, I had a ST "Clone" assembly that didn't shut off completely, and in fact did not appear to bring a Magnum XL .25 to full peak because the NV wasn't threaded far enough. Sort of odd to run the engine with the NV cranked in as far as it would go. 

I put that NV Assy. into a .46LA and it worked fine, except that I couldn't shut off the fuel completely...which is perfectly fine with me.  H^^ Steve