56' 365 main bearing swap in car?

[Drake Danger]

Hi I will appreciate any insight from anybody that has done this before. The Right head cracked into the #4 cylinder exhaust area. It looks like repairing this head is the only way to go, seeing how everybody seems to be fresh out of stock on these heads. Anyhow we did a compression test before pulling the head and all cylinders were in the 125 range besides #3, so I pulled the 2 pistons as well to better inspect them, #3 had both compression rings lined up, that is the only thing that I could clearly see could have created the lower compression in that hole. Well none the less, I pulled all pistons out at this point because #7 had a chip in it and we are going to run the monkey ball through the holes and re-ring all of them. The rod bearings are wearing good and even, but some copper is starting to show through in various spots. This leaves us to believe the Mains are probably in the same condition. I have never done an in car rebuild before, although I have done plenty on a stand. Can the mains be changed out while in the vehicle, with transmission still hooked up and other main caps in place and torqued to spec? I would feel really uncomfortable having to loosen all of the caps at the same time to put bearings in.
L.Todd

[Steve Passmore]

I cant answer for that specific year but I changed many mains back in the day with the motors in place, some even being done in the roadside at my mothers place.   Remove one cap at a time and find something that will fit into the oil hole in the journal leaving just a 16th or so of metal showing.      I think there used to be special tools but we used to find a bolt that would do and cut it off to length, with just the 16th sticking out slowly turn the crankshaft with the bolt on the opposite side to the locator's in the bearing and it should just slide it right round and out.

[Dave Shepherd]

I have had more success loosening all the caps then pull the crank down gently to gain some room, it will not move much as the
chain and trans restrict the movement. There are T shaped tools that fit in the crank oil hole that will allow you to spin out the bearing, as mentioned, going back in with new bearings can be a little harder. Also check the surface finish of the crank before proceeding, it may need an undercut. This is really not the right way to do this.

[Drake Danger]

Thanks for the insight guys. I know this is not the optimal way to do this, but this is the way it has to get done at this point. I have only checked the crank on the rod journals and it still looks great. The bearings are a little worn, but worn evenly so I am hoping I find the same thing on the mains. This whole thing really only started as a head gasket job, but since we found low compression in #3 we thought it might be best to throw some new rings at it and then naturally rod bearings. Then since we are already there might as well do mains if they are similar in wear to the rods, but I haven't pulled a cap yet so we shall see.
SP- I am still a little unclear about your process.
Thank you
L Todd

[Steve Passmore]

You remove a bearing cap completely, as Dave said a good idea to loosen the rest. Without the proper tool, find something that will fit into the oil hole in that journal and remain sticking out just enough to catch the bearing shell when turning the crank, this will push the upper bearing around the journal and out when you turn the crank. Do it on the opposite side to the locator's of coarse.
We used to cut the shank out of a long bolt and smooth it up.       Don.t forget to remove whatever you use after.

I wouldn't advise this method to replace them though, you could easily put a burr on the new shells, use a block of wood to push the new ones around..

[gene harl]

I have used a cut off nail... the head is thin enough to clear the block..
gene harl

[Jay Friedman]

The last time I did this with a friend, we used a large cotter pin.   You put it tail down in a vise almost to the head and then hammer the head flat.  The tail fit right in the hole in the crankshaft and the head was just the right thickness such that it pushed out the bearing without touching anything else.  It's been a while, but as others said they did I think we loosened the bearing caps we weren't working on at that moment. 

We used a similar method to replace the upper half of the rear main seal.  First, after loosening the other bearing caps to lower the crankshaft a thousandth or two, we screwed a wood screw into one side of the seal, then pulled the head of the screw with a pliers, at the same time pushing on the other side of the seal with a rod.  Then pushed in the new one.

[Dave Shepherd]

I checked my tool for this, made by perfect circle.