I have an 85 E350 RV with a 460 engine. Just replaced the battery (Still under warrentee; Napa tested old batt and it was bad,) 2 months ago because it barely cranks the 1st time you turn the key...like the timing is way advanced. But every time there after, it cranks fine. I mean it has a hard time getting the engine to turn over the 1st few revolutions, but turns it and starts it ok every time after the innitial crank. it has a 820 amp Napa battery. I pulled the battery and altinator and had them both checked at Advance Auto, both check good. I pulled the battery terminals, starter relay terminals and pos wire going to starter and wire brushed them including the main ground wire going to the engine block. Surely 820 amps is plenty for this engine, no?
Wire gage I'm not sure of...is close to 1/4" dia so should be a 1 or 2 gage, but not sure if thats large enough. Looks like its been that way for a while though.
Chiltons doesn't show wire size in the book I've got either.
any ideas on this solving problem?
Shooting in the dark here, but did you change the right battery? There should be a starting battery and a service battery (deep cycle) to run the lights and furnace in the RV living area. The starting battery is on the passenger side.
820 CCA seems like a awfully big battery - I've only got a little wallyworld battery on my 1982 RV that cranks out 550 CCA. The deep cycle battery is in front of the driver.