383 Crankshaft Bearing Clearance Question

[Reddartowner]

We're starting to assemble a 383 for my son's '68 Dart and have encountered a possible problem. Upon checking the crank bearing clearances with plastigage, we found all the mains to have just about .003 clearance. The factory manual says clearances should be .0005 to .0015, with a max allowable of .0025. The crank is a .020 under forging and the bearings are Sealed Power 4094M20's. We miked the crank mains and they are right in spec at 2.605 (allowable is 2.6045 - 2.6055). So my question is... do we have to fix this or can we go with it? If it needs to be fixed can we shave .001 off the main caps to increase the crush on the bearings, or is there another way?

Help........

 

[moparlover]

.003 is perfect. good job lol!

http://board.moparts.org/ubbthreads/showflat.php?Number=5932557

 

[Reddartowner]

Thanks for the info. On a hunch, I called Federal Mogul and talked to a tech guy. He gave me the spec shell thickness, and we went and miked all the shells, and lo and behold they all came out almost .001 thin. So we got Summit to take a defective return and they're sending us a new set. We'll mike those shells when we get them, and if they're closer to spec we'll install them and try again with the plastigage...... FYI, Federal Mogul says the clearance range for these bearings is .0008 to .0033.

 

[SGBARRACUDA]

.003 is to loose for my liking. This would lead to early low pressure problems. I've been down that road.