Crank end play on 1924 DB

[Guest Mark.S]

A little history.

I have a 1924 DB Australian built. I have replaced the cam and valves as the new cam i am told the profile is a little different from standard so the exhaust valves don't start to open until the cylinder has complete firing (this eliminates burnt valves) and i replaced the valves as some exhaust valves were rusted shut as the engine sat for over 40 years before i got it. When i first got the car i unstuck the valves put the head back on and had it running.
Technical question time. 
I have the engine being put back together now and i have .014" end play in the crank and the mechanics instruction book has an allowance of .005" end play. Is this too much to let go? How can this be fixed? Is there somewhere i can purchase a new center crank bearing to eliminate this play? 
Any and all advice is greatly appreciated.

Regards

Mark 

[MikeC5]

Hi Mark.  My guess is that the bearing insert would need to be re-babbited and re-fitted which I'm pretty sure has to be done with engine removed.  Is the engine still in the chassis?  THe alternative would be to fire it up and drive it and listen for unhealthy noises.  I have no idea what end play mine has.  Perhaps I should check....   Hopefully someone with more direct experience with this will post.

[Guest Mark.S]

Hi Mike, The engine is out of the car. Can i send the bearings away to have them done and returned completed and ready to reinstall?

[MikeC5]

I'm pretty sure since they are still poured babbit it won't be that easy.  I believe it is still necessary to have to assemble the bearings into the block and line bore to final diameter.  I hope I'm wrong about that...  Maybe a shop could bore based on crank journal measurements you supply but I don't see how they could verify they'd line up with each other when installed.

[MikeC5]

I forgot about this video made by this guy who works at a Ford Model A restoration place.  He appears to know exactly what he's doing with the '25 DB engine.  Although the video is a bit exhausting to watch (you'll see what I mean), if you skip ahead to 4:35 - 7:00 he shows re-babbiting the main bearing inserts.  Skip to 7:20 - 8:50 and he's line boring the mains.  It appears that he bores each main to fit each specific crankshaft journal diameter (assuming they vary slightly).  The rest of the video shows re-doing the rods and reassembling.  He also has a similarly detailed video of rebuilding the transmission and rear end and running the engine for first time, plus reassembling the car, etc.  Good stuff.

 

https://www.youtube.com/watch?v=Cy45P8Fw1QQ

[Guest Mark.S]

I forgot about this video made by this guy who works at a Ford Model A restoration place.  He appears to know exactly what he's doing with the '25 DB engine.  Although the video is a bit exhausting to watch (you'll see what I mean), if you skip ahead to 4:35 - 7:00 he shows re-babbiting the main bearing inserts.  Skip to 7:20 - 8:50 and he's line boring the mains.  It appears that he bores each main to fit each specific crankshaft journal diameter (assuming they vary slightly).  The rest of the video shows re-doing the rods and reassembling.  He also has a similarly detailed video of rebuilding the transmission and rear end and running the engine for first time, plus reassembling the car, etc.  Good stuff.

 

https://www.youtube.com/watch?v=Cy45P8Fw1QQ

I have watched his videos. I also like the transmission and diff videos. I wish he was local or at least on the same side of the world.

i just found a local semi retired engine builder that is going to re-babbit the center bearing thrust surfaces on the top cap. He has the white metal pots and setup and said he learnt from his father during his apprenticeship. Does this sound like a good fix?  

[MikeC5]

I believe the thrust surface is part of the entire babbited area on on the insert.  If so, I would ask how does he plan to just pour a new thrust face only and expect it to bond properly to the original insert/babbit surface.  If he pours the whole insert than you would need to get it line bored and aligned with the end bearings.  Maybe I'm missing something...

[Guest Mark.S]

He said he is only building up the thrust area on the top half as it would be too hard to do to the bottom section in the block without having to line bore the block. He is not touching the inside surface so it will not need line boring.

All the white metal on the thrust area was gone. It looks like the white metal on thrust and inner surface is separate. I am not that mechanical minded but it sounds ok to me.

I asked on here as i need people with experience with these thing to comment.  

[cahartley]

It's babbitt metal, which in automotive engines is a high quality, non lead bearing, babbitt consisting principally of tin, copper and antimony.

Building up a worn bearing flange isn't that difficult if you know what you're doing.

If you don't know what you're doing this is not the right part on which to learn....... 

It's high temperature soldering........any of you who have soldered know how molten solder acts.