88 top end on an 86 bottom. Will it work??

[albertp86]

What do I need to put an 88 top end on an 86 bottom end?? Spacer plate?? Thanks for the assistance.

[wilkin250r]

It depends. Unless you are the original owner, or you have a VERY detailed history on the motor, you don't always know what is in your bottom end. Many of the internal parts interchange.

But for now, let's assume it's an original (or original replacement).

The 86 motors have a different crank than all other years, and you will need an 86-style piston. And to be safe, I'd get the next bore size up, and bore your 88 top end for your new piston. Piston size can vary slightly, even for the same bore size, so you'll want to get your new cylinder bored specifically for your new piston to make sure the clearances are all set properly.

That's it. No spacer plate.

[wilkin250r]

If your crankshaft is an 87-89 style, it will have a longer connecting rod. So you'll need an 87-89 style piston (The wrist pin is in a slight different location to accomodate the longer connecting rod, so the piston crown is the same place). Again, to be safe, next overbore, and that's it.

The spacer plate is only for using an 87-89 style crankshaft with an 86-style piston. It's most common in big-bore engines.

[albertp86]

Thank you for your response. The reason why I asked is because I gave my buddy my 88 top end with a brand new piston to put on his 86 bottom. I am just traying to figure out how to make this all work out.