I have an ’84 Chevy K10 Custom Deluxe with a 4-inch suspension lift with 35-inch Ground Hawgs. I have a 350ci bare block that I’m going to have punched 0.030 over. I’ve built motors for cars before but nothing really for off-roading. I was wondering if you could share some ideas on building a great off-road engine—like which parts and brands to use. I’ve got an idea on how I want to build it, I just don’t know the best way to do it.
The two things to consider when building a motor, no matter if it is for a street-driven car, a pure racing vehicle, or an off- road vehicle is how fast do you want to go and how much money do you have to spend. Because the motor is going in an almost 30-year-old vehicle I am going to surmise that you want to keep expenses down. I have built a couple of 383ci engines that utilize GM 400ci crankshafts and generally speaking have worked out quite well. While not exactly low-cost they do produce a lot of bang for the buck, The 400ci crankshaft has a full ½-inch longer stroke than that of the 350ci V-8. This longer arm with its additional leverage produces a great amount of torque. The 400 crank has to be ground to 350 size on the mains and the block needs to be slightly clearanced. To make engine building and finding the necessary parts a lot easier Northern Autoparts, (www.northernautoparts.com ) has a complete stroker kit including a new Scat crankshaft. That is not to say you couldn’t obtain a 400 crank from a wrecking yard but by the time you find a decent one free of cracks and have it cleaned and ground you almost have as much in it as a new and stronger Scat crank would cost. This configuration will make just about 400hp and the same amount of torque. For an intake system there are several stand-alone fuel injection systems but I have found that other than better fuel mileage the Holly Truck Avenger carb on dual-plane manifold works quite well. If your budget allows go for some Chevy Vortec heads as they breathe quite well. Make sure when you order your intake manifold it is for the proper heads as there is a difference in bolt patterns. Keep in mind that you will also have to purchase a 400 external balancer as well as a flywheel or flexplate for a 400.
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