Sheathing

Size of head shrink (sheathing) for the small wires I only know 3/4 and 1/2 inch

If you are talking about DR25 which is commonly used for sheathing, then that is available down to 1/8 diameter (shrinks to 1/16"). If you are talking about standard polyolefin heat shrink then that stuff is available down to tiny sizes - probably 0.5mm (0.020") or less.

Thanks for the help and I was talking about the sensor wires sheathing such as wideband oxygen sensor or pressure sensors, basically 3 to 6 wires the most for a sensor or in other case DBW throttle body

Anyone know the maximum temperature to use for shrinking DR-25? I see the minimum in their documentation, but not a maximum.

I've done it in a pinch with a non-temp-settable heatgun on its hottest setting, which will be far above any max temp rating I'm sure, you just need to keep a careful eye on it, making sure its not charring or starting to look burnt. Not sure on an exact max temp setting, they might not publish one because that's the temp everyone would end up using, assuming it to be fine in all situations.

Thanks Zac... I started lower temps and the shrink process seemed overly slow, so moved up to around 420 *F and still a bit slow. Wasn’t sure how high I could go to play with it.

Thanks again,

Aaron