How many cranking amps does it take to spin a 540 cubic inch motor . I keep having battery problems . Could my batteries be to small.?I believe I currently have 675 amp batteries.

750 cca is recommended for my 496HO. The battery I have now only puts out 600 cca and I never had any problems.

The amount of amps to crank a big block with a good starter and normal compression ration is somewhere between 75 and 125 amps. It depends on the load on the starter and the length and size of the cables too. That is why most engines need a battery with a cold cranking rating of about 850 amps for the reserve. If your engine is cranking slow from the get-go... then you probably have other issues. You can purchase small batteries with high cranking amps... but they are so small that they don't have much energy in reserve and the power is drained quickly.

I Would Look At The Starter!!

I'll bet you still have that big, "heavy duty" electromagnet field starter in there. I went through this with with dual 850 MCA batteries and still cranked slow when hot. Go to the "Hi-Torque", gear reduction, permanent magnet field, little guy and all your problems will be over. --- Jer

THATS WHAT I USE !!!!

Interstate makes a good 800 cca battery big cables then look at the battery switch most are rated for 250 to350 amps. Timing makes a big difference on how it cranks you may need to use a retard if every thing is in order. Should have a surge 200 to 400 to start cranking check the voltage at the battery and at the starter to see how bad the drop is needs to stay above 10.5 at the starter to crank . Good Luck

Gear Reduction Starter And Your Troubles Are Gone. I Had The Monster Starter Before And It Needed 2 Batteries But With The New Starter Its No Problem. Also Make Sure You Have Good Grounds. Powdercoating Looks Nice But Reeks Havok On Electrical.

merc is now recomending 850cca as of this year

i might suggest to check youe elec. system, from front to back. even though you have all this starting or cranking power , you still may not have the ability to start the engine correctly. and at the same time doing unseen damage.
having adequately sized and in good condition cable is important, as is a battery switch rated for the starting or "surge amperage" for your application. bad ground's and wiring are the foundation for most ghost or simple problem's.i use -2 0t for most applications.

good luck....