Slowgoer: Stick with the 235, it will outlast any V-8 and is cheaper to run and is way more COOL in your AD. You stated in your other post that your 235 had new bearings 200 miles ago and now you have problems on #2 & #4 rods. Who did the bearings? Did you put them in yourself? New mains also? Did a shop do the work? Now you have the pan off and are checking things out, is there any other damage thats visible to crank, rods, or piston/wristpin areas? Cylinders scored? How are you measuring the journals, with plasticgage? Calipers, or what? Do you have access to micrometers or a dial bore gauge? If so, do you or a friend know how to use them? The causes of bearing failures are many and without more info its hard to tell what going on. Stock 61 235 rod journals will be 2.311/2.312 inches in diameter. Normal rod wear will cause the shaft to wear into a slight ellipse and the bearing also. Stock oil clearence for 235 rods is .0007/.0028 (factory specs). When the bearings were changed were the rod/pistons removed? If so, possibly rods and or caps were replaced out of position, and /or caps mismatched with the corresponding correct rod. Were the rods torqued correctly? The rods and number matching caps need to be installed with the numbered sides toward the camshaft and torqued to 35-45 ft. lbs.. What kind of shape are the rods in? Twisted or bent? Maybe the large end could be out of round? If the bearings have dirt on the undersides of the inserts or on the parting faces, and when torqued will distort out of round. This distortion or excessive "crush" can cut off the oil clearence and rapidly ruin the bearings in 200 miles or less. You need to check the crankshaft rod journals for taper and out of roundness. If out of round you have to fit bearing to the maximum diameter. If the roundness varies more than .002 the crankshaft needs to be reground. The big end of the connecting rods needs to be 2.4367/2.4372 (stock dimension), and if elongated and or distorted more than .002 should be reconditioned or replaced. Also rod bores (big end to pin end) need to be parrallel to within .001 in 6 inches. You would be suprised how many bearings are hammered out of engines by bent/twisted rods. You need to check this this stuff out so to figure your next move. Engine bearing problems are usually pretty straightforward, if you know what your parameters are and what to look for. Pick up a shop manual for your truck and arm yourself with some information. There are alot of sharp minds on this site and we will help you through this. Repost your findings! taskforcetrucks :confused:
