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  1. Need injector help

    Performance Discussion
    I am swapping a 1989 4b into my TJ. As some will know the first Gen Cummins B engines, from 89-93 had 9mm injector holes. This led to lots of cracked heads. In 94 they switched to 7mm holes and the p7100 fuel pump. My stock head off the 4b was cracked, so I bought a second hand head from a skid...
  2. 40-50hp injectors for 4bt

    General Discussion
    Hey I'm new to the site. You guys always seem to have the answers to everyone's questions. I've got an 83 short bed Chevy 2wd. Finally found a 4bt a few weeks ago and started working on it. It's a VE pump, hy35, and I'm still needing the gov. Spring and fuel pin. Im wanting 40-50hp injectors...
  3. 6bt w/ diffrent egts at exhaust

    Cummins Tech Section
    I had removed the muffler and increased the injecting timing from 12.3 to a bout 16 degrees before tdc. Now i notice what seemed to be a missed, so I did a temp. check at the exhaust and notice that the #3 was at 130, 2 and 4 where at 120, #1 was at like 110 and 5, number 6 was at 95. So i...
  4. piston question

    General Discussion
    piston/injector question I'm in the process of rebuilding a 4bt and am almost through with the machine work. I've made a few mistakes such as not researching 4bt's completely. The motor I purchased was manufactured in 1986 and original parts are hard to find. For instance the valve seals are...
  5. New injectors and 4 BT spare parts

    General Classifieds
    H1C it worked great and does have a good bit of play but not hitting and very usable or rebuild-able. It has a 3 in intake. 125 Fluid dampened motor mounts 100 90 deg angled intake neck 60 stock intake tube with the rubber ends 50 stock intake cover plate 30 stock bottom rear dump...
  6. Help me understand mechanical Injectors

    Cummins Tech Section
    I have an understanting how they work, I think. BUt im unclear how injectors can provide more horsepower. Does it flow better while maintaining a correct spray pattern with the same pulse with from the pump?? Or do the factory injectors limit the flow of the pump before the limits of the...
  7. Engine miss.

    Cummins Tech Section
    Injectors are good, and have been pressure checked. Valves adjusted Compression test good, all 4 around 400 I still have a miss. Low power, poor fuel economy. If I keep the idle around 760 when i put it in gear it LOPES. What else to check?
  8. Engine Repairs & Stacking the Deck Against Yourself

    General Discussion
    This is only a suggestion for the newer folks with limited Cummins engine exposure and pertains to doing multiple engine repairs to a running engine and ending up with an engine that will not start. The first thing you should do is a test run of your engine immediately after your purchase...