G'day...I've just put my car in the shop to have some World S/R heads and a Comp cams XE262 fitted, ported Plenum and port matched intake and AFPR added. It already has Hooker headers and free flow 3 inch single exhaust
One of my mates said yu might get bottom end problems due to new heads going on and everything being re tightened.

Question is: On a 305 TPI is this an issue with 60k on the clock? and or at what stage HP wise is the bottom end on a 305 likely to give problems?

The car is due to get a 100-150 Shot TPI NOS kit added a couple of weeks after other mods are done and I've been to the track to update my times.

i wouldn't worry about it too much untill you give it a shot of juice. when you start running power adders you'd want forged parts, like pistons and crank.

Ede:

Question:The After market chip which I have installed gives me aggressive timing. Will a timing retard box that MSD makes, defeat the advance the chip is trying to acheive when I set the timing to retard on the MSD box for nitrous runs?

As long as it has TPI on it, that will protect the bottom end from even nominal stress, and guarantee a long and easy life for it.

60,000 miles is nearly brand-new for a small block Chevy that has been properly cared for. I have a car with a 305 that we bought when it had 60,000 miles on it; it now has 345,000 on it, and the intake manifold hasn't been off yet. The timing cover has; but not the intake or heads.

Is it necessary to retard the timing using only a 100 shot of NOS or will the current knock sensor do the job?