• Using a 3400 fuel rail with a 3500 upper intake

    Using a 3400 fuel rail with a 3500 upper intake

    3500 swaps and 3500 top end swaps have their own quirks to making the installation work properly, and the 3500s returnless fuel rail system is one of them. The 3100 and 3400 rail/injectors all fit the 3500 lower intake, but the upper intake has a clearance issue with the fuel pressure regulator. The…


  • 3400/3500 Hybrid Parts

    3400/3500 Hybrid Parts

    The LX9 3500 gives 3400 owners an excellent upgrade path, but also introduces more confusion. Here is a simple breakdown to how it all works. Sorry, 3500 heads should not be used on a 3100 due to the bore/combustion chamber overlap. Using 3500 heads on a 3400 lowers compression to about 9:1 on a …


  • Gen 1/Gen 3 Hybrid Setup

    Gen 1/Gen 3 Hybrid Setup

    The Gen 1 Iron Head motors were always limited by the cylinder heads.  When GM upgraded the block with aluminum heads for the FWD vehicles, they kept the RWD engines iron head.  If you are willing to run fuel injection, the aluminum head swap is a fantastic upgrade.  The 2.8 and 3.1 engines have …


  • Comparing Flowbench Results

    Comparing Flowbench Results

    Trying to compare flowbench numbers from various sources is a lot like comparing OEM horsepower ratings.  The method of testing has changed over the decades, and the individual tests use different calibrations and corrections.  Being able to test with the same operator and equipment for thousands …


  • Head Gasket Thickness / Quench

    Head Gasket Thickness / Quench

    Now that we have Cometic MLS Head gaskets for these engines, there are more choices to be made. The main focus of questions has been the compression ratio possible with thinner gaskets. This is a great idea, but depending on your engine, it could work against you as well.  The following is copi…


  • Lifter Preload

    Lifter Preload

    Lifter preload is important for a hydraulic lifter to function properly. To understand why, you should first know how a hydraulic lifter is built. The above diagram shows the internal bits, which doesn't exactly make things any easier to undestand just yet, but the diagram below shows how th…


  • Nut and Bolt Sheet for 3400 V6

    Nut and Bolt Sheet for 3400 V6

    WOT-Tech Nut and Bolt Sheet for GM 3400 V6 3400 Bolt and Nut Index Bolt QTY Stud QTY Nut QTY Notes          Throttle Body Bracket M…


  • Making a Cable Bracket for the LX5 Throttle Body

    Making a Cable Bracket for the LX5 Throttle Body

    We offer both cable brackets individually, or as part of a package with the adapter, throttle body, and gaskets.  If you would rather make your own bracket, the following pictures will give you an idea of what is involved.  The 3400 style brackets are much easier to source, and modify but are not …


  • Head Milling vs Compression

    Head Milling vs Compression

    We usually only mill enough to make a head flat, but sometimes a customer wants more off to increase compression.   What exactly is there to gain?  Its a small sample size of 1, but we cut .010" off and measured.  Then did it twice more to see how it scales as you remove more.  The only note wo…


  • Rocker Arms for Gen 3/4 60V6

    Rocker Arms for Gen 3/4 60V6

    When the first Gen 3 engines came out in late 1993, they were still using the hardened pushrods, pushrod guideplates, and a ball fulcrum.  They did get an upgrade to 1.6:1, which is useful for anyone with a gen 2 looking for a quick and easy upgrade.  Starting in 1996, the GM 60V6s saw an upgraded…


  • LH0 3.1 MPFI Torque Specs

    LH0 3.1 MPFI Torque Specs

    General Data: All dimensions are in millimeters Type 60 degree V6 Displacement 3.1L RPO LH0 Bore 89.0 Stroke …



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