If a 200/229 distributor was installed in a 4.3, it would fire the first cylinder at the 132* mark not the 120 that the motor needed.About 12* late by my calculations.The next cylinder would actually fire on time.132 + 108 = 240. The 4.3 on the other hand, is a true even fire motor.The rod journals have a 30* offset requiring a cylinder to fire every 120*.ġ20, 120, 120, 120, 120, 120.Again 2 full rotations of the crank and a total of 720* Being a 90* 6 cylinder motor.A cylinder would fire after 132* of crankshaft rotation, and again after another 108*, then 132 again, 108, 132,108.2 full rotations of the crank, a full 720* This was done to make the motor run smoother. The 200/229 engines have an 18* offset on the rod throws. These above are what may pertain the the OP's situation a bit more than the later balance shaft EFI engines. Obviously, this is just the tip of the iceberg- the 4.3L V6 went through a crapper load of changes through the years. Four different crankshaft castings were used in the first of the 2nd generation engine: 10105865, 14088640, 1408885480. Heads were c/n 140792248.īlock c/n 14088553 was the 1-piece rear main seal w/flat tappet cam, used in 1986. Crank was c/n 1174N externally balanced, even fire w/2.25 rod journals. The LB1 engine had the non-feedback Q-jet carb/intake and the non-feedback distributor needed when ditching TBI, etc.īlock c/n 14071177 was the 1985-'86 (there were both 1- and 2-piece RMS engines used in '86) 2-piece rear main seal w/flat tappet cam. For a performance build, the balance shaft can be deleted and the any balance-shaft oil-feed holes plugged.ġ996-up balance-shaft motors have true Vortec heads- at least the majority of them. The non-balancer shaft 'Z' code TBI engines could still be found through '95. In 1992, the 4,3L V6 got a balance shaft for smoothness.

4.3 vortec engine identification