+- Austinsevenfriends (https://www.austinsevenfriends.co.uk/forum)
+-- Forum: Austin Seven Friends Forum (https://www.austinsevenfriends.co.uk/forum/forumdisplay.php?fid=1)
+--- Forum: Forum chat... (https://www.austinsevenfriends.co.uk/forum/forumdisplay.php?fid=14)
+--- Thread: Re-babbiting big end bearings (/showthread.php?tid=729)
Re-babbiting big end bearings - Greig Smith - 22-01-2018
Hello Gents
As the title says I'm in this predicament, short version - 1930 engine found on a farm running a water pump, now in our '30 single seater special, (built circa 1949, abandoned in the mid '50's, found in the 80's & rebuilt by Dad over 10 years ago), matching block, rods and crank - we have no reason to believe that they are not the original Longbridge babbited big ends. 1 & 5/16ths crank, 40 thou oversize pistons, Alta high compression head and twin SU's with banana branch exhaust.
It's run the Simola Hillclimb, (Knysna South Africa) three times, went very well, but the last one was in the hands of my lovely wife who obeyed my request to not exceed 5000 rpm by holding it at 6000 all the way up the hill in 3rd gear when the red mist descended.
Needless to say the big ends are now a bit tired & I will need to re-white metal them before the next Hillclimb on the 4th of April - we have a block of Hoyts white metal and a fairly well equipped workshop & we're game to tackle almost anything.
What I'm really looking for is a bit of guidance & hopefully a few pictures of the jigs and fixtures etc that you use to hold the rods, the jig to form the hole in the centre and then guidance on ladles & pouring the metal - I've read all the usual A7 books on the subject, done the You-Tube thing, but I'd appreciate a few pointers from the learned masters here. We have a lathe and the usual MIG, Arc & gas welders & access to a milling machine so I can fabricate jigs etc.
My local engineering shop will bore the newly metalled rods out to suit the crank, so that's no issue. The crank itself is basically unmarked, a few faint lines, but after 88 years I expected far worse & it will easily polish out - have already had it crack tested & amazingly enough it's still perfect, as are the rods. The car won't be campaigned 10/10ths - she's just for fun, the new weapon for Simola will be the new supercharged 7 I'm building, but that's a story for another thread
Beloved also boiled it on the line while waiting (someone spun and we waited too long), I missed the gauge climbing while checking on something and I had to fill a gallon of water in a hurry - makes for an impressive photo anyway. Fortunately I caught it before any damage and the rings and bores are 100%
Cheers
Greig
Port Elizabeth
Sunny South Africa
'26 Chummy
'28 Top Hat Type R
'33 Type "65"
'30 Single seater special
'30 Supercharged single seater special
Other lesser makes
RE: Re-babbiting big end bearings - Colin Reed - 22-01-2018
Hi Greg, Regarding the remetaling,
they are done separately the cop and rod so you need only have half a jig,
will try and explain how it is done make the jig so it will clamp in a vice say on a 100x100 mm angle iron
looking down from the top you will have a 50x 10mm plate at the back standing up to this you bolt a half round probably around 28mm for the core you then need to machine to half discs that locate the rod in place allowing for metal to form the two thrust faces the rod and cap at this stage will be horizontal so the metal is poured in from the top.
Next you will need two melting pots that will keep a steady temp,
one for the white metal and one pure tin
also tinning powder
the process is
melt the old metal out of the rod and cap clean the surfaces to be metaled
then heat them an rub in the tinning powder till you have a complete film
then dip them into the hot tin then straight into the jig which has been preheated
then using a small ladle with a spout slowly pour in the metal and using a small rod to make sure that it is not leaving air pockets
Hope this is of some help
Colin
RE: Re-babbiting big end bearings - Bob Culver - 23-01-2018
Many older textbooks detail remetalling. Vintage car cubs and library stack rooms often have such books. Solder is suggested for tinning and the option, suited small scale work, of heating from the back and applying a stick is covered. Modern Motor Repair and Overhaul, Newnes vol 2 (1930s) uses sand moulds. Automobile Workshop Practice, Staton Abbey uses a presumably metal jig. No details about sealing. Both books tantalisingly lacking in many details. Someone may be able to recommend better, or fill in the gaps..
I gather current practice is to retain the two feed/vent holes but not the trench as original.
Ruairidh previously provided a photo of a commonly used boring jig arrangement. May save some deep thinking as few now familiar with.
RE: Re-babbiting big end bearings - Stuart Giles - 23-01-2018
Hoyt's produced a book called "The Hoyt book on the lined Bearing" which is the best "how to" book for white metalling I've seen. My paper copy came from a junkshop years ago. But there appears to be a PDF scan of it here: http://www.boatregister.net/Library/Maritime%20History/HoytBookOnTheLinedBearing_1.pdf
Edit: Just skimmed through the PDF version, and unfortunately, it does have a lot less pages (and information) than my (10th edition, apparently) paper version, which has over 100 pages. the shorter online version is still worth a read though IMO.
RE: Re-babbiting big end bearings - Colin Reed - 23-01-2018
Hi Greig,
Should have explained what I was recommending is the way it was done in NZ not from books but first hand having served my Time as an engine reconditioner casting and machining main & conrods.
Cheers Colin
RE: Re-babbiting big end bearings - Ruairidh Dunford - 23-01-2018
The con rod boring jig I have belongs to a friend. It is meant for a Myford but he made me an adaptor plate so that I can run it on my Boxford - it is incredibly useful.
He has just finished making a half mould/jig to babbit Austin Seven rods.
Colin and Stuart's posts are very well timed and useful for this particular project, thanks for sharing.
RE: Re-babbiting big end bearings - Charles P - 23-01-2018
(23-01-2018, 10:36 PM)YRuairidh Dunford Wrote: The con rod boring jig I have belongs to a friend. It is meant for a Myford but he made me an adaptor plate so that I can run it on my Boxford - it is incredibly useful.
He has just finished making a half mould/jig to babbit Austin Seven rods.
Colin and Stuart's posts are very well timed and useful for this particular project, thanks for sharing.
I'd love to see some pictures of it R
Thanks
C
RE: Re-babbiting big end bearings - Ruairidh Dunford - 23-01-2018
I have a short film of it here Charles: https://flic.kr/p/W7jmXZ
RE: Re-babbiting big end bearings - Colin Reed - 23-01-2018
(23-01-2018, 10:36 PM)Ruairidh Dunford Wrote: The con rod boring jig I have belongs to a friend. It is meant for a Myford but he made me an adaptor plate so that I can run it on my Boxford - it is incredibly useful.Hi Ruairidh,
He has just finished making a half mould/jig to babbit Austin Seven rods.
Colin and Stuart's posts are very well timed and useful for this particular project, thanks for sharing.
When putting the grove in the rod half only take it within 1/16th of the edge of the radius not right through and to one side of the Holes and does not need to be as deep as appears on Greigs photo
Cheers Colin
RE: Re-babbiting big end bearings - Ruairidh Dunford - 23-01-2018
Thanks Colin! I have feeling there will be some more questions coming your way, if you don't mind, please?
That booklet is very interesting indeed Stuart - gem of a link!