The MGA With An Attitude
TORQUE SPECIFICATIONS for Nuts and Bolts - CF-112
At 03:56 AM 7/5/2007 -0600, Doug Cygan wrote:
>>"I've looked through all of my books including the workshop manual and only found some of the torque specifications, but not all."
Torque specs shown in the shop manual are the critical ones. Otherwise apply general torque specs according to bolt size.
>>3/8" = 35-45 lb-ft
>>5/16" = 20-25 lb-ft
>>1/4" = 10-12 lb-ft
Find a tabulation of torque specifications for Unified Standard threads of various grades in UT-120 in the Universal Tech section.
Find a tabulation of bolt head markings for Unified Standard fasteners of various grades in UT-121 in the Universal Tech section.
There is one vague torque reference in the shop manual. Where it says "Clutch to flywheel bolts" it should say "Flywheel to crankshaft bolts" = 35-40 lb-ft.
>>Cylinder Head: 50 lb-ft
>>Rocker Pedestal bolts, 5/16": 25 lb-ft
>>Connecting rods: 35 lb-ft
>>Gudgeon Pin clamp bolt: 25 lb-ft
>>Flywheel to Crankshaft: 35-40 lb-ft (and remember to cinch up the locktabs)"
>>Clutch Cover to Flywheel: 25 lb-ft
>>Water Pump bolts: 25 lb-ft
>>Manifold nuts: 25 lb-ft
Four of the six manifold studs go through into head bolt holes. Here you may have oil weep through the threads to smoke and burn when it hits the hot exhaust manifold. Apply a little thread sealant to the base threads on these studs to prevent weeping oil.
>>Camshaft nut: 100 lb-ft
>>Crankshaft nut: 100 lb-ft
I've never measured torque on these. Just make them tight, and cinch up the lock tabs.
>>Oil Pan: 10-12 lb-ft - These are bit special.
These are only 1/4" screws. Make the pan flange flat first. Eyeball under a straight edge to gauge flatness. Use a flat face hammer to tap down any protrusion around bolt holes. Glue gasket to the flange with a little blue stuff (Permatex fuel proof silicone). Install pan and torque screws with a nut driver, just enough to cause the blue stuff to squeeze out of the joint. Let set for 12 hours to cure, then torque screws a little more (10-12). This is not a structural joint, only sealing a gasket. Over-torque will only deform the flange (and may cause leaks).
Before installing the pan, use a razor knife to shave the square cork seals at the main caps flush with bottom of block, and apply a dab of blue stuff to the cork surface.
>>Timing Cover: 25 lb-ft
Similar to the oil pan, except there are two bolt sizes here. The 1/4" screws only need nut driver torque to seal the gasket (10-12 lb-ft). The 5/16" screws hold front plate to block and provide structural support for engine on engine mounts. These need 25 lb-ft.
>>Valve Cover: 5-10 lb-ft
Lots of people make a big mistake here. You could break something with excess torque. You can do these with a nut driver too. See here: engine tech - CH-104.htm
The valve cover must be flat on bottom or the gasket will not seal, regardless of torque. Make the cover flat first. Glue cork gasket to cover with blue stuff. Apply a smear of oil on bottom of gasket as a release agent. Top of cover gets two rubber grommets, cup washers, thick spacer washers, and the cap nuts. Torque on the nuts should only squeeze the rubber grommets. The cup washers should NOT bottom out on the valve cover. The valve cover "floats" between the rubber grommets and the cork gasket. See here: engine tech - CH-107.htm
>>Water Outlet (thermostat cover): 25 lb-ft
This is just a soft cork gasket, nothing structural. Just squeeze the cork so it doesn't leak with low pressure inside, no sealant required. One important item here. Two of the three studs go through into the water jacket. You should apply thread sealant to the bottom end threads on the studs to prevent fluid from weeping up around the threads. If you don't, then water getting up between the cover and studs can rust the studs enough to make it near impossible to remove the cover later (in addition to leaking fluid around the lockwashers on top).