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I'm going to be using my 4BT powered truck for towing so I need to fab up an exhaust brake. I need to be sure to have the proper valve spring seat pressures so that ex-brake doesn't blow exhaust valves off their seats into piston heads. I've heard 1st Gen CTD ex. valve springs referred to as '30 lbs' or '60 lbs' springs, but this doesn't sound right to me. Smallblock or bigblock Mopar flat tappet cams run about 130-150 lbs spring seat pressure, and roller cams can run as high as 300 lbs. So '30 lbs' springs sound a little on the puny side.

Anybody know the Cummins spec on exhaust valve spring and seat pressure? Is it really only 30 lbs? Thanks...
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