i am having an issue starting the engine , acts like a week battery very slow to turn the engine over . it will crank very very slow then get up to speed till engine starts . battery was tested good, I have a msd mini starter with a thermal blanket to protect from header heat . i have replaced the battery terminals .car does this even when its been sitting over night. need ideas on what to look for before I buy a new starter

 

It sounds like your battery cables are not up to par. Weak cables or maybe bad grounds, ground from battery to frame, then frame to the engine block are a must have. A good + Cable battery to starter. Before changing the starter I would try using jumper cables along with the battery in the car and cables you have, and attach the jumper cables directly to the starter and see if that makes a difference. then after that try jumpers on the existing battery and see if that makes a difference. I don`t think it`s the starter.(I have been wrong sometimes) But it can be a loose connection in the starter heating up and making contact, or (maybe) Bad contact on or inside the solenoid could do the same thing. That`s all I got.. Good luck on your hunt!

 

Timing and compression ratio can put a heavy load on a starter.
Is this something that just happened or did it happen when the mini starter was installed?