monte70car Posted September 25, 2011 Share Posted September 25, 2011 Guys and girls what would cause a motor to turn over so slow? Motor is a 355 with roughly 1350 miles on it set up for TPI tried two different batteries still would turn over slow, pulled the plugs and tried again still slow almost like a grinding sound when it turns over. All push rods will spin easy. Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted September 25, 2011 Share Posted September 25, 2011 Starter getting weak? old? maybe Quote Link to comment Share on other sites More sharing options...
robs70monte Posted September 25, 2011 Share Posted September 25, 2011 Ya sounds like a weak starter or bad connections on the starter Quote Link to comment Share on other sites More sharing options...
DavidTX Posted September 25, 2011 Share Posted September 25, 2011 Sounds like the starter needs shimming to me. Quote Link to comment Share on other sites More sharing options...
robs70monte Posted September 25, 2011 Share Posted September 25, 2011 Is it loud or grinding Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted September 26, 2011 Share Posted September 26, 2011 Measure the amp draw with ammeter in either the positive, or ground cable, of the starter motor while cranking the engine over. If the amp draw is excessive, according to the manufactures specifications, then the starter motor is faulty. Slow cranking or high current draw can also indicate that the bushing may be worn and cause an off-center armature. Worn bushings and or an off-center armature causes poling and throw off the alignment of the magnetic fields. Worn brushes..oil bathed, and by all means the solenoid current transfer internal bolt head. Located inside the solenoid.. A good working solenoid is a must. The AMP Draw is the most important I suppose!! Your small block "355" no doubt a higher compression motor? What starter are you using? Any difference if you pull the plugs,, how easy does it turn over? Quote Link to comment Share on other sites More sharing options...
monte70car Posted September 26, 2011 Author Share Posted September 26, 2011 Rod the compression is 9.75:1 starter is a chrome mini starter and no difference with the plugs pulled still slow when it turns over. Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted September 26, 2011 Share Posted September 26, 2011 Have we got a good ground?.. Mostly concerned with AMP draw at this point? Will the motor turn over easy by hand? Quote Link to comment Share on other sites More sharing options...
monte70car Posted September 26, 2011 Author Share Posted September 26, 2011 Yep grounds are good one off of the battery to the block with a pigtail hooked to the inner fender, grounds for the TPI system hooked to the back of the transmission. Motor turns over easy with a flywheel wrench. Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted September 26, 2011 Share Posted September 26, 2011 I would measure voltage at the battery while cranking. Then measure the voltage at the starter while cranking and see if there is a voltage drop. I would then take a voltage measurement between the negative terminal and the block while cranking to insure that the cables are in good shape. Quote Link to comment Share on other sites More sharing options...
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