If you have the long rod, I would use the later piston and cylinder with no spacer plate. I don't like the spacer plates, just use the parts that will work together. Either all short rod (piston and rod) or all long rod (piston and rod). The cylinder doesn't matter, all will interchange. I have a good running 86 and a later style (bridged intake) on the bench. Just use good parts, break it in right, use good oil, and keep up on your maintainance.

 

am i banned???

 

I just want to clear something up before people start thinking too hard and confuse themselves. The stroke of an 86-87 crank is the exact same as an 88-89 crank: 72mm. The length of the rod has nothing to do with stroke. The only thing the rod does is change the length between the crank pin and wrist pin centerlines. The crank pin is only 36mm away from the crank centerline (36mm radius). It moves from 36mm below the centerline (BDC) to 36mm above the centerline (TDC) on each revolution. 36mm X 2 = 72mm. You could have a ten foot long connecting rod on that crank, and it would still only move 72mm vertically each revolution.

The advantages to using the long rod (without using a spacer) is to decrease the piston weight (less compression height and shorter wrist pin bosses), reduce rod angle and cylinder wall loading at BDC, and increase the dwell time at both BDC and TDC. The reduction in piston weight almost becomes a moot point because the longer rod is heavier, but it is still beneficial.

 

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