|Rebuilding your B18/B20, part one
In our last issue, we ran part one of this series. If you followed it precisely, you should now have a good idea of where you're going with your rebuild project, where to buy parts and tools, and you've found a good automotive machine shop. You should also have a partially disassembled block in your garage, and you should have a good idea about what sort of condition it's in.
Please review the steps we went through to get to this point and get caught up as necessary at this time.
Having disassembled the motor to this point, everyone will need to order gasket sets for both the upper and lower end of the engine. If you don't already have catalogs from ipd and RPR, click over to their websites and order them now.
If you've determined that your engine's bottom end is in good shape and you want to keep it stock, no further disassembly is required. There is no better time, however, to replace the main and connecting rod "big end" bearings (inexpensive), and to upgrade your front and rear main seals. You can either trade in your present seal housings, or order just the new seals and have your housings machined. You might also want to "re-ring" your pistons -- ipd carries Deves brand rings (pronounced "Davies") which are specially made to seat quickly in slightly worn cylinder bores.
We recommend that you use new bolts when reassembling the crankshaft bearing retainers -- torquing these to specifications stretches the bolts a very slight amount, and replacing them with new parts results in a tremendously strong unit.
If your block requires an overbore, it will have to come completely apart, and you should order the engine rebuild kit with the pistons of your choice from ipd. If your block or head is beyond hope of rebuilding, RPR can supply fully built-up replacements.
For those who want to install a "hotter" cam, we recommend a complete ipd kit, including new bearings, pushrods and valve springs. Your machine shop will have to modify the head slightly to accommodate the new springs (Iskenderian no longer supplies the cutter that ipd once rented with its kits). A word of caution: while these cam profiles are well-developed for street use, be aware that these cams will cost you some low-RPM power, idling smoothness and, possibly, fuel economy. Any one cam will seem more "radical" in a 1800cc motor than in a 2130cc big bore. Consider your driving habits and other motor mods carefully when choosing a cam -- "bigger" is not necessarily "better."
As long as you're taking everything apart, disassemble the oil pump and inspect it. There should be a negligible amount of play in the gears -- if there's more, order a whole new pump.
ipd carries a "Block Sundries Kit" which includes all the soft plugs and some handy hardware for reassembling the motor. You can reuse most of your hardware if you prefer, but new lock washers are a nice touch and are readily available at your local auto parts emporium. Do not use lock washers on highly torqued fasteners such as head bolts or bearing retainer caps.
Tearing down the motor
We're starting where we left off in the last issue, and we're going to take the block completely down to "parade rest." Modify this procedure as necessary to suit your particular case.
- Turn the crankshaft so the #1 piston is at top dead center (TDC) and the distributor rotor is pointed towards #1 (forward and towards the block, in a normal installation). Undo the distributor clamp and remove the whole assembly by pulling it straight out.
- Make a drawing of the exact angle at which the distributor drive gear is sitting. Note that the slot in it is offset to one side. Then reach in with long-nose pliers and pull out the gear and its shaft. Check for slop between the shaft and the bushing in the block -- it is easy to replace the bushing if necessary.
- Jam the cam timing gears with a folded shop rag. Undo the nut on the nose of the cam. Use a gear puller to remove the gear from the cam (carefully, if you're going to reuse it). Save the spacer behind the gear. If you're going to replace the cam, remove the Woodruff key from the nose of the old cam; otherwise leave it on.
- Unbolt the brass retainer plate and remove it. Pull out the cam while supporting it from the bottom -- sharp cam lobes can easily gouge the soft cam bearings.
- Working on one set at a time, undo the nuts on the big end bearings and carefully tap the pistons out the top of the block. Remember that each set is made of matched parts (usually, they're stamped 1 through 4) and note which side faces forward. Most pistons have a shallow slot in the top surface -- this faces the front of the motor.
- In a similar manner, take the main bearings loose and carefully lift out the crankshaft. Always keep the crankshaft lying horizontally and well-supported -- it's easier to bend than you might think, and you don't want to have to replace it. If you're going to replace the pilot bearing (recommended), pull it out of the rear of the crank now (I use a slide hammer). In most cases, you can just leave the metal timing gear on the front.
- Remove the brass timing gear oiler fitting from the block and guard it carefully. Also remove the dipstick tube and the water petcock.
- Remove the two oil galley plugs from the bottom front of the block. These are usually a ¼" square drive, so you can use a ¼" socket adapter as a driver.
- If you're going to replace the pistons or the wristpin bearings, remove the circlips in the pistons and push the wristpins out.
- Put the crankshaft bearing caps back into their correct positions and snug their bolts down.
You are now ready to haul a bunch of stuff to the machine shop.
Next section: Machine shop and reassembly.
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