ive got a set of 317s on my silvy SS and want to go to 243s for the compression bump. what parts can i take off of my 317s and put on my 243s??? im guessing a shorter push rod will be needed?? will the valves and rockers interchange??? thanks in advance Mark

 

if it is an LQ9 your already 10:1 with the 317s

 

the 243s and 317s use same parts. now a ls6-243 has longer and lighter valves. a
ls2/ls4/5.3/4.8-243 head uses standard valves

if you bought bare heads you can use your 317 valves. your pushrods wont change.

with using 243s your compression on a LQ9 will be 11.1