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Early vs Late SOHC Crankshaft

408 Views 4 Replies 3 Participants Last post by  Buster28
I’m in the middle of throwing in a rebuilt 3.2 SOHC longblock. Slowly. I work on it 5 minutes at a time. Anyway, I recently came across a thread here where it was mentioned that early and later SOHC crankshafts are not compatible due to the change in ignition types (waste-spark to coil-on-plug). That all makes sense, but how can I tell if the engine I have from Engineworld is the one for my early system (93 Trooper)? Everything has swapped over so far, including the crank sensor. But the valve covers were slightly different, a few different mounting points compared to the ones on the original engine. Is there an indicator I can look for? Did I miss read and any year SOHC block will work? I’d hate to start over, but I’d hate more to get it completely reassembled before learning any bad news.
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Thanks. That is the info I am looking for. This is going to be one nervous tooth count.
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Thanks Ed Mc for the guidance. I count 6. Well technically the cylinder 1 TDC notch is a double gap, but that's how the system locates itself. Posting some pictures here in case anyone else needs to ever clear this up. Not sure what the coil-on-plug crankshaft pulse wheel looks like. But this is what the early style waste-spark (3 coil packs mounted on the ignition module) pulse wheel looks like.

First turn the crankshaft to the cylinder 1 top dead center (TDC) position by aligning the notch in the crank pulley/balancer with the zero on the timing belt cover.
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Then remove your crankshaft position sensor and look for gaps in the pulse wheel when still at the zero position. Unless something is seriously wrong, you should have a double gap here. The double gap allows the system to tell the difference between cylinder 1 TDC, and all the other points in the rotation.
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As you rotate the crankshaft 360 degrees back to zero (cylinder 1 TDC) you will count 5 single gaps like this.
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In total you will have 6 points on the pulse wheel that excite the crank sensor. One of those points is a double gap, five of those points a single gap. Hope this helps.
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