Cadillac 346 Flathead crankshaft rod bearing problem with grinding the shaft

[Ron Parker]

The bolt on counter weights are over the rod journals by 1/8th "and the crank can not be ground all the way. Has anyone else had this problem? Are all the cranks this way? I have read that the counter weights should not be removed. I am thinking of boring the rod bearings to give them clearance on the uncut part of the crank. I made an arbor the size of the crank on the lathe and clamped my old rod bearings on with a hose clamp leaving 1/4" out. I used a sharp tool at high rpm and took off .010 . It looks good .The alternative would be to narrow the bearing. Any thoughts? Thanks Ron Parker

[Paul Phillips]

Ron
The counterweights can be removed for machining, though it is a bit of a challenge due to the OE screws. Plan on the possibility you may end up destructively removing the screws. Mark the counterweights so they can go back in the same place. We ended up using socket head screws & cutting down the heads so they sit flush with the counterweights. Red Loctite helps make sure things stay put.  Bearing inserts are available in normal oversize ranges for mains & rods. I sourced mine from Terrill Machine, but there are other choices.


Hope this helps!
Paul

[Ron Parker]

Thanks,I am still wondering if all the 346 cranks are like this. I have another to rebuild and it will be easier now that I have learned some of the tricks. Ron Parker

[Steve Passmore]

The cranks are not the same in that the early engines had these screws but from the start of WW2 they had changed the counterweight fixings to bolts.  It will depend on what year your engine Ron.

[Daniel Szydel]

Ron
I just removed the counter weights on an engine I’m rebuilding and it wasn’t a huge deal. If it’s the slotted screw head, take a small drill and remove as much of the curl of metal that’s in the slot. Use chisels and a pick to get the rest of it out. I used a drag link socket bit and a big breaker bar to get the bolts out. The key is to get something that fits the slot really well. I layed it on the floor and pushed it against the work bench leg while someone helped brace it.

The bottom of the weight has hollow dowel pins so you may have to tap it off.

Dan

[Ron Parker]

Thanks, Thats cool to see. Are you going to use the same bolts or use a socket head bolt? Are you going to use red locktite or just torque it?This is my first Flathead and it has been a learning experience. Ron Parker

[Daniel Szydel]

Ron

I ended up using a crank out of a 48 engine which had the hex head bolts.  That was put back together with red locktite.  I have a post in the restoration section titled 1946 convertible project underway where I explain what happened.
I did buy Allen bolts that I planned on using with red locktite.  Of course you will have to open up the counterbore in the weight and check thread depth in the crank.   

dan

[The Tassie Devil(le)]

Any alterations in this area will require the whole shebang to be re-balanced.

Which is what I do with any engine I rebuild that requires crankshaft machining, boring, and piston replacement, especially when going for higher compression pistons.

Bruce.