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| <<BACK | ||||||||||||||||||||||||||||||||||||||
| <<HOME>> | ||||||||||||||||||||||||||||||||||||||
| DOHC Shortblock | ||||||||||||||||||||||||||||||||||||||
| Items needed: | ||||||||||||||||||||||||||||||||||||||
| 2.5L Chrysler Short Block (complete) | ||||||||||||||||||||||||||||||||||||||
| MLS (multilayer) head gasket for DOHC cylinder head | ||||||||||||||||||||||||||||||||||||||
| 3 steel plugs - .695 to .705" approx (the holes on my block varied in size) - 3/4" long | ||||||||||||||||||||||||||||||||||||||
| 2 steel plugs - .350" - 3/4" long | ||||||||||||||||||||||||||||||||||||||
| Loctite 620 (sleeve retainer) | ||||||||||||||||||||||||||||||||||||||
| 2 - Mopar DOHC dowel pins for block - p/n 4448856 | 1 - Aeroquip (-12AN to 1/2npt straight) or similar | |||||||||||||||||||||||||||||||||||||
| 1 - Aeroquip (-4AN to 1/8NPT straight) or similiar | ||||||||||||||||||||||||||||||||||||||
| 1.1 - Remove stock dowel pins from deck of block. | ||||||||||||||||||||||||||||||||||||||
| 1.2 - Drill out two corner bolt holes to fit dowel pins in. Place dowel pins in. | ||||||||||||||||||||||||||||||||||||||
| 1.3 - Plug (1) all three oil return passages (large holes), (2) one oil feed hole (small hole) and (3) one crankcase pressure equalization hole (small hole) on the front on the block using the 3 - .700" (approx) and 2 - .350" steel plugs. Ensure that loctite is used to keep the plugs in place. | ||||||||||||||||||||||||||||||||||||||
| 1.4 - Remove stock turbo oil drain-back tube from block. Tap hole for 1/2 NPT and insert -10AN to 1/2 NPT fitting. This will be used for oil drain-back for the cylinder head. Save the stock tube for next step. | ||||||||||||||||||||||||||||||||||||||
| 1.5 - Remove oil pan and weld the stock drain-back tube on the back/middle of the pan. This will be used for the turbo oil drain. | ||||||||||||||||||||||||||||||||||||||
| 1.6 - Cut a notch in the stock passenger side engine mount. NOTE: The DOHC cylinder head overhangs the block, and requires more room than the stock 8v head. | ||||||||||||||||||||||||||||||||||||||
| 1.7 - Using the MLS head gasket, mark on block where cooling holes need to be aligned. (Note that the crankcase pressure equalization hole closely matches where an original oil drain back hole was (cylinder #3). Grind out cooling passages to align with MLS gasket and drill out equalization hole. | ||||||||||||||||||||||||||||||||||||||
| 1.8 - The oil distribution block on the front of the block needs one additional outlet added. Drill and tap the original one for 1/8" NPT. This will be used to run oil into the cylinder head. | ||||||||||||||||||||||||||||||||||||||
| 1.9 - Optional step - cut notches into top of stock pistons or replace with custom pistons. - You can use a die grinder to make additional room for valve clearance with the stock pistons. - Some reports say that stock pistons with no modifications will work with this head. - It is important to note that the stock 8v head is a *non-interference style engine - by going to the DOHC cylinder head, the engine becomes an **interference style engine. |
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| * Non-interference: When the valves on the cylinder head are open, the piston will not be able to contact them in ANY position in the bore. If the timing belt breaks, there will be no way of causing valve/piston damage due to the fact that there is enough clearance between the piston and the valves at all positions they may have in relation to each other. | ||||||||||||||||||||||||||||||||||||||
| ** Interference: The valves and the piston will not contact each other as long as the timing between the two is maintained (ie - by the timing belt). If this timing is not maintained (Ie - timing belt breaks) the pistons will hit the valves when they are in an open position. Honda engines would be a good example of this. | ||||||||||||||||||||||||||||||||||||||