• Hi Guest! Being a Paying Supporter is NOT a requirement to participate at BCF. However, subscribing will help ensure we can continue to serve the LBC community for years to come. If you enjoy BCF and find our forum a useful resource...Please consider supporting us by **Upgrading**
    (PS: Subscribers don't see this banner)
Tips
Tips

MGB Crank doesnt turn freely - new main brgs

saltiga

Senior Member
Offline
boggsy, I have just restored a"T "engine and I found the crank locked up on tightening the big ends and also the mains I double checked the crank journals and big ends for size they were perfect , checked they had the correct markings on the under size slippers, these were also correct. so I tried each big end and found they locked up, the mains were the same. What had transpired with a previous owner/mechanic had files the caps to tighten the clearance for the existing wear, so when the journals were brought back to a standard the con-rod and main bearing journals were now undersized, Had the mains reline bored to original size, the big ends were also resized , checked clearances of each journal, all ok, engine now turn over very sweetly Hope this is not your problem . I have been told it was a common practice with older engines. Saltiga
 
OP
Boggsy64

Boggsy64

Jedi Hopeful
Offline
Lots of good comments: Update: I checked the ring gaps and all appear correct. My bore is .010 over and checked out at 3.168 or so with a simple calipers. I don't have a bore gauge handy or snap gauge but think it is correctly .010 over (should then be 3.17). Using a rule of thumb of .0035 inch gap for each inch of bore I came up with about 11 thou gap. I checked the compression rings and the first (lowest) ring is right at 11, the upper ring is 14 or 15 thou. This seems right to me from reading a chevy 350 website discussing rings and competition compression. There is stated that the first ring should have a tighter gap than the second. In any event no filing of the rings necessary in my case.
The crank does turn OK now, will not coast but will turn freely and smoothly. This my main issue was using 30weight oil instead of assembly lube on the main bearings (I later used proper assembly lube) and as I tightened all the caps it loosened up. I was told that the bearings are not fully spherical until compressed. Seems to be logical and this incident seems to back that up?
 
Similar threads
Thread starter Title Forum Replies Date
nichola TR6 Door handle and window crank installation Triumph 0
D TR2/3/3A TR3 throttle linkage bell crank. Triumph 13
R Wanted 3 main crank MG Classifieds 1
Twit early TR4 Crank Handle wanted Triumph Classifieds 0
P TR6 Tight window crank Triumph 9
71TR6 Triumph TR4 Coventry Radiator with crank hole- recently refurbished Triumph Classifieds 0
D TR2/3/3A TR3A Crank Dog Triumph 2
K TR2/3/3A The timing mark on the crank pulley.... Triumph 5
K For Sale Starter Hand Crank Triumph Classifieds 0
J 1275 EN40 Crank Spridgets 5
J TR2/3/3A Flywheel-Crank Dowel Alignment Triumph 6
R TR2/3/3A Extension Crank Bolt Attachment Triumph 12
M Wanted TR3 Hand Crank Guide Triumph Classifieds 3
Alfred E. Neuman TR4/4A TR4 fan extension and crank bolt length Triumph 9
D TR2/3/3A Crank handle support Triumph 11
Got_All_4 TR2/3/3A Hand crank misalignment Triumph 9
K For Sale TR3 crank handle Triumph Classifieds 0
M Wanted TR-3 Crank Handle Triumph Classifieds 3
R TR2/3/3A Temperature Gauge for 1954 TR-2 & Hand Crank Triumph 17
Got_All_4 TR2/3/3A TR3 engine hand crank Triumph 14
ckeithjordan Wanted WTB: TR3 Crank Handle Guide Stays Triumph Classifieds 1
Drone Dog BT7 tri-carb installing my crank Austin Healey 4
R General Tech Crank bearing cap broke...Torque?? Triumph 37
Rut Crank/flywheel dowels Spridgets 3
R TR2/3/3A One more crank pulley question Triumph 7
R TR2/3/3A Crank pulley question Triumph 4
GTP1960 TR2/3/3A Timing cover/crank hub oil seal Question Triumph 4
jfarris TR2/3/3A TR3 tining without marks on crank pully Triumph 6
T Replacing the crank pulley/damper Austin Healey 4
T TR4/4A How to determine if the crank is good before pulling the engine out Triumph 8
R Crank damper alignment Austin Healey 6
R timing gear crank shims Austin Healey 11
R Dennis Welch Rear Crank seal conversion - Gap in back plate Austin Healey 19
R Engine crank shaft nuts Austin Healey 1
B Remove Crank Nut Austin Healey 55
M_Pied_Lourd TR2/3/3A Crank Oil Slinger Orientation Triumph 2
S TR4/4A Water pump and crank nose questions Triumph 7
GTP1960 TR2/3/3A Removing the fan extension from the Crank hub Triumph 13
T TR2/3/3A How many guide holes in TR3 flywheel for crank pin? Triumph 2
M Crank Pulley Removal Austin Healey 12
J General TR Narrow Belt crank pulley Triumph 0
T TR4/4A Oil drain hole from rear crank seal/rear main cap Triumph 3
K TR2/3/3A Su carb rod linkage bell crank stud? Triumph 6
CJD TR2/3/3A Crank balancing Triumph 11
B Chip off the crank pulley Austin Healey 12
HJR TR2/3/3A Crankshaft crank bolt head[108498] Triumph 10
jaegzie Size on head on end of crank Spridgets 1
Scotsman TR2/3/3A Crank Pulley Triumph 2
Geo Hahn TR4/4A Crank Bolt Size Triumph 5
PatGalvin TR2/3/3A TR3A Crank pulley removal Triumph 9

Similar threads

Top