Good morning all,

I currently have the 88 pulled apart down to the case and gathering everything I need for assembly. The only thing I'm confused about are the dowel o-rings between the case/cylinders and cylinders/heads. Which dowels get an o-ring?

I've searched for an answer and looked in the manual. I'm confident that for the case to cylinder its the fwd most dowel on the front and aft most dowel for the rear cylinder (outer dowels) since those are the only ones that are recessed. Although I did find an oring on the inner dowel of the rear cylinder and not the front. And yes, I did carefully watch as I pulled the cylinder off so the oring did not fall into the case.

For the cylinders to head, the manual only shows an oring on the outer dowels, but there were orings on all four dowels when I pulled it apart. It would makes sense to me that all four dowels get an oring if it is meant to keep the head gasket aligned. I read MLS gaskets omit the orings and I may go that direction.

Thanks for any help.

 

There are two oil return dowels on the bottom (case to cylinder) require o-rings and, depending on the head gasket, o-rings may or may not be required up top (head to cylinder). IIRC, the MoCo made a change to the OEM head gasket (not sure when) so that the OEM head gasket fits tight to the oil return dowels and eliminate the o-ring. The Cometic head gaskets do not require an o-rig as they fit tight to the oil return dowels. Consider using a .030" Cometic head gasket when re-assembling in lieu of the .045" OEM head gasket. This will boost compression a tad, about .2 points IIRC which is a good thing. You will need to follow the Cometic instruction for torqueing their head gasket as they are different from the instructions in the service manual.

The way your last paragraph is written, it sounds as though you are saying there are four dowels between the cylinder and head but that can't be so I assume when you make reference to four dowels you are referring to two at the bottom and two at the top.

 

Thank you for the info. So both dowels on each case to cylinder requires an oring? Just want to make sure I get it right so it doesn't cause a leak.

Sorry I worded that last paragraph wrong. I meant two dowels between each cylinder and head.

 

Read my post again. If the head gasket fits tight to the dowel, no o-ring; Cometic head gasket will fit tight to the dowel and, IIRC, later OEM head gaskets do as well but not sure. If the head gasket does not fit tight to the dowel, use the o-ring. As suggested in my previous, use the .030" Cometic and get a little bump in compression.

 

Thanks, I understood the head gasket advice and I definitely will be going with that.

My concern are the dowels located between the crankcase and cylinder (picture attached). My question is if only the dowel with the recessed area get the oring or if both get one. I don't want to end up putting an oring on the non-recessed dowel if it isn't supposed to be there and it causing the cylinder to be tilted and leak when torqued down.

 

Only the dowell with the resess.

 

Thank you!