earlier this year i began my first rebuild and i meticulously cleaned and prepped all my parts before building. The long block is complete however i have a few concerns.

So I've done a search about general first start up and break in procedures for a fresh rebuild, however there are a few questions i have concerning and signs that may tell me ive built the engine correctly before it's in the car.

First off, the motor is an s4 tii mild street port with s5 rotor housings. One concern i have is when turning the engine over by hand with a 12 inch ratchet. As i rotate the engine by hand it will spin pretty freely but sometimes after i stop turning the ratchet the engine has a sort of recoil/ spring back. Is this normal, or is it a sign of a bad rebuild has anybody else felt/seen this after a fresh rebuild? I will note that the regular 6 distinct puffs can be heard when rotating and nothing sounds or feels like its grinding or scraping around inside the engine.

I'm not very experienced with these engines but the only explanation i can think of is that if the engine is built right and has decent compression, the air may be trying to push its way out which may be why sometimes i can feel a spring back while turning it over by hand.

Any thoughts are welcome, id prefer an experienced builders opinion but beggars can't be choosers.

 

from what you described, it doesn't sound like anything is wrong. the short answer/explanation is: just remember that you're compressing air, and that requires an applied force. there will be an equal force resisting until you stop.

long as you clearanced everything correctly, you're getting your 6 pulses, nothing is grinding and your front stack (endplay) is in order, you should be good to go.