LB rebuild

D

deeprock

Member
So, I finally disassembled my LB engine. Pistons are already .040 over. It will need to be bored. Is .060 a problem? I have domed pistons. Now for the crank shaft... Already had .020 undersized bearings. It should be turned. But now I here finding oversize bearings is next to impossible. Guidance please.
-shad
 
it is hard to find bearings .40 and over in my experience and they are very expensive. sometimes its cheaper to find another crank.
 
cranks turn up,I got a free LB engine the other month .030 bore and std crank.
you got to be lucky sometimes.
Lawrie
 
Not sure it's the same on the LB's but the builders who post here normally claim that 0.060" over is about the limit on the early 21 stud poured babbitt engines. There have also been a few posts claiming they broke through into the water jacket just under 0.060". Maybe with your block the cylinders will clean up at less than 0.060"
Are the mains and rods both 0.020" under now?
 
Last edited:
.060 bore is no problem, I don't recommend over .060 but I have bore .080 with no problem, also I've bored through at .060 on rusted blocks on the inside of the water jacket. You can find .030 -.040 rod bearings with enough checking and asking questions. Also the 37-38 21 stud has the same crank as the 36LB. Walt
 
Along with the mixed results as reported above on .60 over, you might consider sleaves and standard pistons from the outset due to the tendency to overheat with thinner water jackets.
 
Both rods and mains are @ .020" under. Do they make .050 oversized pistons?
Alan, why would you have overheating problems with thinner cylinder wall?
Thanks for the help!
-shad
 
Shad, I can't document the fact, I only remember reading it somewhere, but that was printed in an actual book instead of the internet where everything you read must be true! :D
I remember the explanation was that thinner walls contribute to hot spots and cavitation, thereby reducing heat transfer. Sounds logical, so I'll go with that!
 
Talk to EGGE machine about the pistons,I don't think they make 050,but no harm in asking.
lawrie
 
Be carefull with undersize rod bearing journals on a LB or earlier engine. I rebuilt my LB engine about 5 years ago, and had a terrible time locating replacement rod bearings. The rod bearing inserts on that engine are flanged (later flat head rod bearing inserts are not flanged), and even though many of the supplier websites listed them in their catalogs, when I tried to order them they were found to be unavailable. I ended up spending several weeks searching around on e-bay and several different V8 clubs before I found a complete set for my engine, which had the crank bearing journals bored undersize.
 
Ok so all my parts are gathered. Started the assembly process, are the connection rod designed to have locking clips for the nuts? This engine was in pieces when I purchased.
 
deeprock said:
Ok so all my parts are gathered. Started the assembly process, are the connection rod designed to have locking clips for the nuts? This engine was in pieces when I purchased.
Click to expand...

I use rod nuts with the slots around the top (like hacksaw slots) there self locking. The rods usually need recondition, the bearings turn in the rods and the crank, those flanged bearings are made for the 32-38. Walt
 
There is a set available that is -.030crank/+.010rod. Check out Ebay item number 231727318741. If your rods are reconditioned already these will not work. I previously purchased a set from that seller and was pleased with what I received. Haven't used them yet.
 
You must log in or register to reply here.
Back
Top