Generation IV External Engine - necessary to use air ? on LSX

to change springs, how much clearnce on top of piston at TDC ? is it necessary to use air or how deep will the value fall into the cyl>
thanks far much needed help
Johnny

oops sorry wrong form , some one please move to interenal

You can use the TDC method, but I've always been leary of it because if the locks stick, your putting all the force of compressing the spring on the valve itself, risking bending it.

use a bump stater to put the given piston at TDC and swap out the springs for that given cylinder. If the Piston is at TDC Then valves wont fall very much at all, the pistons are proud and stick up out of the bore a tiny bit. you wont have any problems changing the springs with the piston at TDC. Put a socket over the retainer and smack it with a hammer before you put on your valve spring compressor and you wont have any problems with the locks sticking. Don't smack it hard just hard enough to break them loose, you will feel it.