arrow stiffness
 

Is a 27 inch 5575 with a 100 grain tip a stiff enough arrow for a 70 lb 1.5 cam bow?

RE: arrow stiffness
 

Need more info.

Which bow, draw length (Hoyt?)
Being the arrow is a 5575, I assume it is a Gold Tip.

I will make some assumptions about your setup but if......
Your bow is a Hoyt Ultratec 70#/28" draw AND
your arrow is a Gold Tip XT Hunter 5575 at 27" with a 100gr tip

The arrow is probably OK. It is just a hair on the weak side of what TAP says is perfectly spined.
That being said, if my assumptions above are remotely close, I think you would be better off with lowering your draw weight a smidge to 67#. The Hoyt C.5 bows seem to like an arrow slightly on the stiff side.

If your bow has a higher IBO speed than the Ultratec then the arrow will be even more on the weak side
If your draw is shorter than 28" then you are probably fine with your arrow combination.

RE: arrow stiffness
 

The bow is a hoyt ultra mag, 60-70#/27-29.5 inch draw (IBO is 300 i believe)

The arrows are gold tips, i have both xthunters and expedition hunters

Any idea how many counter clockwise turns it takes to get from 70# to the correct poundage for these arrows?

RE: arrow stiffness
 

Gold Tips are generally underspined. You would be better off with a 7595 arrow.

RE: arrow stiffness
 

I was shooting 28" 5575's out of my 70# BK2 @ 30" with no issues.