Was it just being anal,, or..... warranted
Motor is back in the truck, but went to prime the oiling system and something was just not right. I pulled the oil pump apart and inspected, checked, blueprinted cleaned, and re-used the oil pump from the last build with this assembly (in a GM block before) Everything was fine. Dropped the ARP shaft in, put the oil pump on and went happily about my way with the rest of the assembly.
Fastforward a month and the motor is built in a Dart LittleM block, Have to prime the oiling system before I can put the carbs on (cant get the distributor in and out once the carbs are in place and is a MAJOR PITA to pull the carbs).
Anyways something was wrong. I could 'feel a drag on the oil pump primer trying to turn it by hand before I even put any oil in the pan. It would 'turn' but it was WAY too tight. Put a Dewalt cordless on it and it would spin ,, used a 1/4" ratchet and it would turn, but it was too stinking tight. Suspected the oil pump shaft when I put it in, but was too stupid to think it through. Anyways,, end result is I can't get the pan all the way off with the motor in the chassis (motor plate, mid plate and rear trans mount so it's a big PITA to even raise or try to pivot the motor in the chassis, but the pan iwill hang down enough to get the scraper tray and oil pump out (with MUCH cussing and knashing of teeth!!)
So here is what I found. The ARP pump shaft is about 0.002" smaller than the hole bored in the Dart Little-M rear main cap. It clears until you put a distributor (or primer) in it and pull the shaft into alignment. If the ARP shaft was tapered just 1/4" farther up, it would clear. But JUST CLEAR doesn't sound right to me. I'm taking the shadt to my sons and chucking it in a lathe and cutting about 0.050" off the whole polished area to have 0.020"+ clearance all around.
So which would have happened if I hadn't decided I wasn't going to risk the motor over pulling it apart in the truck to check WTF was wrong. Would it have heated up and split the rear main, siezed and twisted the shaft in half, or would the oil flooding down the back of the block been enough to make this OK??????
The Macro lense shows what little actual material was pushed around spinning it with the primer and dewalt drill. Really only polished off the black oxide coating.
I mean it's apart and getting fixed right,, but be aware,, the Dart Little M block / ARP pump shaft has this issue. Actually it's not exclusive to the ARP shaft, the stock 400 shaft has the same diamerer within 0.002" and extends even taller . This wouldn't be so bad if I didn't have a similar issue withthe Motorw block in the Nova and a Titian oil pump. Almost same problem withthe Titian shaft binding under the pump and had to pull the motor to correct it. You'd think I'd learn from m mistakes. Apparently NOT!!!!
09-28-2011, 04:34 PM
Hybrid Mode
