What can happen if you reinstalled rear head without being at TDC?

 

Would this cause extremely low compression for that cylinder?

 

I don't think anything if its only the head.

If you installed the rockers and the lifters werent bled down when tightening it could possibly pull the threads from the lower rocker box because the push rod would be pushing up. If it were started this way it could cause a valve to hit the top of the piston and could bend.

hope that made sense.

 

all depends as to where it was when you did it. Were you doing it with push rods in place? Stock rods? You could have bent valve(s) and it sounds like you may have with low compression. Take it back off.

 

Same stock rods..simply installed the 110 drop in kit replacing the 103..Don't remember if we adjusted for TDC for the rear after installing the front... Front works fine

 

take the rocker cover off the rear, bring the cylinder to TDC, and see if there is a lot of clearance between the rocker and the valve, if so, valves are bent

 

So the end result was the exhaust and intake rods were switched.. Bonehead mistake... Surprisingly no damage to rods, piston or valve.. Easy fix

 

Great to hear!