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Old 12-11-2019, 01:17 AM   #13
cas3
Senior Member
 
Join Date: Jan 2011
Location: sw minnesota
Posts: 4,543
Default Re: 33 Rear Main Leak

while i am no expert, here's my hillbilly thoughts. first, its got the vent hole in the block, so should have the vented pan. we have'nt seen seen the front of the block yet, so could even be later than 35 if the water pump block off plates are there. doesnt matter really, if it has the vent hole in the block i believe it should have a vented pan. hard to argue 33's with david j, but i see no reason that the intake manifold should matter. i believe the pan vent was introduced in 35 to make the road draft vacuum pull the oil vapors out the bottom and reduce oil smell in the car. so if it has a diamond shaped port under the fuel pump stand, 33-34, the tube to connect the the 35&up draft system wont be there. the tube was to keep the draft going past the lifter galley and down to main crankcase where all the action is.massive turbulence going on there, which could push oil out the rear main, so good place to have a vent. so, we know its not the original motor, but my thought is whoever changed it most likely put the old manifold back on to make it look correct, or because the carb was good and all the connections then went on without issues. so...now we get on to ken with the cool zepher coupe, he's got a point about rear main clearance. since the pan is off already, i would pull the rear main and check it. first, you may be lucky and its an lb motor. either way i would first check with a dial indicator to see if the crank is round, i think a half a thou is spec by memory, and then support the crank with a bottle jack and do a plastigauge check to see what the overall clearance is. if your results show an out of round crank, i would still fool around with the shims (if its a babbot motor) to snug it up a bit. one of my model a's has a bad crank and i tightened it up as best i could 20k miles ago. still has an occasional main knock, but i expect many more miles yet

Last edited by cas3; 12-11-2019 at 01:33 AM. Reason: to add
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