Installing a postwar crank in a prewar block.

Good Morning Everyone:

I was going to install a postwar crank in my prewar standard bore block (1941) and it seems that the 26H rods don't fit down the bore. Am I missing something here? Has anyone else run into this and how did you work it out?

Thanks,

Mike L.

The later cranks have larger rod journals ,never done this on a V12 but I do know you run into the same problem on the V8s.

Mike, If the block is 2-7/8" bore the rods without the caps on should slide right in. The rod journals are only 1/8" bigger in diameter. If you plan to use the pre '42 flywheel you will need to machine off the pilot bearing hub on the crank otherwise use the appropriate flexible fly wheel to match the starter(drive) you plan to use .

Thanks for the reply flatcat and peecher. I will try the rods without caps and see if that will work. Also thanks for the reminder about the flywheel peecher. I have noticed that you are very thorough. Its good to have someone with your knowledge of these cars to coach us through our dilemmas.

Mike L.

Peecher: I checked the bore. It is 2-3/4" prewar. Can we insert the pistons and rods from the bottom? Another question I have: Can I use straight stem new style valves with the original hydraulic lifters?

Thanks,

Mike L.

Yes, you can use the straight stem valves and one-piece guides on any V12. The pistons however need to be installed from the top. You can actually put some of the bare (ringless) pistons in from the bottom. Have you tried inserting the 26H rod? Never tried this on a 2-3/4 bore myself but I think they would still go?

I have used this combo for many miles.. larger bearings without the sludge traps, better dampened flywheel and 26h rods..

pistons go through the top! Trash the old mushroom valves, use v-8 1 piece guides and valves..use lz springs..High volume pump

if desired and exacting tolerances make the 12 a good runner..(so far)

Thanks again Mssr. Are you sure the 26H rods go through the top when the bore is 2-3/4"? My engine building buddy says not. I'm with you on the other points you mentioned.

Mike L.

I may have mis understood the question, I have a 2-7/8 block ..oversized .060 I believe..

I know the rod caps were off but I dont recall any issue ..