60 degree 4 cyl looper, taper pins

[Frank Acampora]

Gentlemen: Save me a little hassle. On the 96 60 degree 115 looper, Which way do the taper pins that locate the front and rear halves of the block drive out? Toward the front or rear of the block? The taper is not very pronounced and the manual doesn't say. Thanks!

 

[Dhadley]

Re: 60 degree 4 cyl looper, taper pins

The pins drive in from the front half (carb side), drive out from the rear (block side).

 

[Frank Acampora]

Re: 60 degree 4 cyl looper, taper pins

That's going to make my life a lot easier. Thanks.
Last 4 cyl I did, pins appeared to be stuck --couldn't seem to drive them either way--and I separated the block (with much difficulty) without driving them out. Was worried that I would crack the flange. Don't even want to try that on this little gem.

 

[Dhadley]

Re: 60 degree 4 cyl looper, taper pins

All OMC / BRP pins go in from the front to back. Some people think they are nails and drive then in as such on a rebuild. All they are designed to be is a guide.

 

[Frank Acampora]

Re: 60 degree 4 cyl looper, taper pins

Not exactly just a guide! They are quite important. During manufacture, the block halves are lined up and the taper pin holes are drilled. The pins are driven in to temporarily hold the two halves in alignment That's why they are tapered. THEN the assembly is line bored for the crank, cheek seals, and bearings. So the pins locate the block halves positively with no play at all for 100% accurate assembly after machining. Since the assembly screws/bolts need some play to be assembled, they can not hold the two halves in alignment sufficient to ensure proper sealing and bearing performance.

That is why you can not mate the front crankcase half of one block assembly with the back half of another. It is also why you can not dress down the flanges more than, oh, say, 1 thousandth or so. If you go much further, the block assembly must be re- line bored.

 

[Dhadley]

Re: 60 degree 4 cyl looper, taper pins

They are guides. Once installed the line up the front half. They don't have to be driven in like a nail. The front half is a matching half on an OMC but you can mix if you know what to look for.

 

[Frank Acampora]

Re: 60 degree 4 cyl looper, taper pins

Agreed! You say tomayto, I say tomahto but it's the same fruit.