Exgie

Push rod or not it doesn't matter they can still crash. A push rod motor just has more stuff to demolish.

Cool Beans

I asked various Chev/GM service people and one gave me double talk and another said for me to Google.......Two others said non-interference..... and one said the push-rods are the weak link that will give way first, before damage is done. Both said they had never heard of a chain giving way and causing damage.

Guess we are OK and thank you for all the comments

73shark

Not sure why you were worried about it in the first place but trust me, the push-rods are not the weak link. The valve head is at an angle to the top of the piston and will bend easier than the push-rods. Timing chains usually get worn to the point that the timing is off so much that the engine won't start. Of course w/ newer engines w/ crank sensors that won't happen. Bottom line is that timing chains seldom break on OHV engines.

Exgie

True. This is all true. It is very unlikely a chain will ever break. They are generally considered lifetime. Further more as mentioned on a new car they will set off all kinds of errors when something is wrong with the valve train. Moreover, they make all kinds of racket and if you still haven't addressed the issue you deserve to get all your stuff mashed up. However a lot of modern cars do use hydraulic tensioners which do fail.

The bottom line is as stated it is not something that you need to worry about. It is very rare to have chain failure and it will give you plenty of notice before failing.

Rednucleus

My 68 327 quit coming off the freeway one day - just like turning off the key (200k+ miles). Found the nylon gear had sheared off about 1/2 it's teeth. No other engine damage. Started right up with new gears & chain.

Exgie

That was something that happened often on old SBC.

73shark

Usually if you are lucky, you would only lose a tooth or two due to the wear and the timing would jump to the point the engine wouldn't start when you shut it off. Did you check compression on all 8 cylinders to make sure that one or more valves were slightly bent?

FWIW, you can probably get a steel replacement cam gear.

Randy Main

"Mickey "