{"id":245,"date":"2018-03-10T16:06:42","date_gmt":"2018-03-11T00:06:42","guid":{"rendered":"http:\/\/www.nickpisca.com\/diesel\/?p=245"},"modified":"2018-03-11T21:47:06","modified_gmt":"2018-03-12T04:47:06","slug":"7-3-idi-connecting-rod-and-bearing-work","status":"publish","type":"post","link":"https:\/\/www.nickpisca.com\/diesel\/fuel-system\/7-3-idi-connecting-rod-and-bearing-work\/","title":{"rendered":"7.3 IDI Connecting Rod and Bearing Work"},"content":{"rendered":"

If you have been following my progress with the latest rebuild<\/a>, you know I left off at the point of measuring the gaps in the rod bearings.\u00a0 I got the crank mains measured and successfully installed the new crank in the ’94 block.\u00a0 Next I need to verify that all rod bearings are within spec as well.<\/p>\n

For the uninstallation of the pistons and rods, check the aforementioned link for all that prep.\u00a0 Removal is pretty simple, just undo the cap nuts and pry off the rod caps.\u00a0 Then push the piston out of the top of the deck.<\/p>\n

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After pulling and labeling all the pistons, I laid them on the table to assess their condition.\u00a0 In order to pull off my plan, I need to move the ’88 crank into the ’94 IDI block.\u00a0 That means, to make things easy, I need to bring the ’88 connecting rods with me as well.\u00a0 Which means I need to transfer each respective piston from the ’94 cylinders with their ’88 connecting rod companion.\u00a0 Since neither of these engines were rated for the turbo, that means the pins are interchangeable.\u00a0 (On the turbo version, the pins are slightly larger diameter.\u00a0 The NA version has 1.110″ diameter pins, while the Turbo has 1.308″ pins.\u00a0 NOTE:\u00a0 If you try to swap to the turbo setup, you need to find the companion turbo-rated pistons as well.\u00a0 I’m planning on writing an IDI piston ring write up once I collect all my photos.)<\/p>\n

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Lucky for me, I measured my pins with my schnazzy new calipers and they were both within three ten-thousands of each other.\u00a0 That is effectively an identical diameter, so either the ’94 or the ’88 pins would be usable.\u00a0 I elected to go with the ’94 pins, just because I’m going with the ’94 pistons, so I know they nested in the piston already.<\/p>\n

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I drew up a chart to make sure that I mate the proper connecting rod with their respective piston.\u00a0 This way, I make sure that my pistons go exactly with the right cylinder, and the connecting rod goes exactly back with the respective position on the crank.\u00a0 (However, this is kind of unnecessary, because I measured the bores and journals, and I am replacing the rings, and custom sizing them per each cylinder, and I’m replacing the rod bearings, but regardless, it’s good practice to label and identify every part in the engine.\u00a0 But in the beginning of this rebuild, my original plan was to reuse the existing piston rings, but after a gap inspection, that was scrapped for a plan to custom gap oversized rings.\u00a0 Article to be written.<\/em>)<\/p>\n

Pressing out the pins.<\/em><\/p>\n

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I laid out the pistons and their respective partners from the opposite engine.\u00a0 My drawing above explained which rods went with which piston.\u00a0 The process is pretty easy:\u00a0 using a needle nose pliers, I pulled out the pin retainers and pushed out the piston pin through one side.\u00a0 Then I carefully made sure the pistons were oriented the exact same way (using the rod letters and the piston pre-cup depressions as guides), and swapped the rods.\u00a0 Using a lint-free towel, I cleaned the pins and journals, and then applied some clean new engine oil to the surfaces to make sure they are properly lubed.<\/p>\n

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Installing and Measuring the Rod Bearings.<\/em><\/p>\n

With the pistons and rods properly swapped, I archived the ’88 pistons and ’94 rods, and took the good rods and pistons to the vice.\u00a0 Careful not to damage the piston, I mounted the rods in the vice to have the bearings sized.<\/p>\n

\"\"When doing a bearing project, you will need to order new bearings.\u00a0 Bearings come in various sizes, based on the machining of the crankshaft journals.\u00a0 The only way to get a ballpark figure on ordering a new set, is to flip over the bearings in the rod and cap, and read the text on the back.\u00a0 Typically, they come in “Standard,” “0.010,” “0.020,” and “0.030” oversized.\u00a0 As the crank journals are ground down in machining, they are sized in increments of ten thousandths (one hundredths).\u00a0 \u00a0The purpose of the bearing is to make up this difference.\u00a0 Unlike the crank bearings<\/a>, the rod bearings do not have an “UPPER” or “LOWER” designation.<\/p>\n

I ordered a set of 0.010 oversized bearings for my rods a while ago, and I’m now ready to install them.\u00a0 The old bearings slide out pretty easily.\u00a0 I cleaned up the rods and caps, removing any oil or grime that might have coated the mating surfaces.\u00a0 Then, WITHOUT APPLYING ASSEMBLY LUBE OR OIL, I installed the replacement bearings in the rod and cap.\u00a0 Dry.\u00a0 Also, there is a notch and key in the bearing that needs to line up.<\/p>\n

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Then I put the cap on, and torqued the rod cap nuts down to the proper spec:\u00a0 38 ft-lbs on the first torque, then 51 ft-lbs on the final pass.<\/p>\n

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\"\"With the cap properly torqued on, it now is compressed into the size for operation.\u00a0 Using a bore gauge and micrometer, I needed to make sure that the bore conformed to the proper dimensions.\u00a0 I had already measured the crankshaft journals when I did the crank bearings (explained in the other article), and wrote down the dimensions accordingly.\u00a0 All of the rod journals measured between 2.4882″ – 2.4885″ in the X and Y direction (of course the x and y are arbitrary because the rod rotates, but you get the point).<\/p>\n

From the Ford Service manual:<\/p>\n

Connecting Rod Journal Diameter<\/strong><\/p>\n