Tom Monroe's book says if it deflects more than 1/2 inch then relpace it.

 

Go by the 1/2" rule, but if there's any doubt in your mind, just replace them. If you going with stock gears/chain, they're pretty inexpensive, and since you're already there, you'll save yourself a ton of work by not having to even think about it again for at least 70,000 miles or more.

 

Yeah I will replace the chain and gears. I thought the rule of thumb was 1/2" play but it's been a long time since I have ripped an engine apart I couldn't remember for sure. Anymore I just lease vehicles so I wont have to work on them. Thanks.

 

A friend of mine had the chain and gears replaced in 1999 and this spring opening the engine, he found almost an inch of play. All this without much miles. Makes me wonder.

 

High valve spring pressure, high lift cams, and high RPMs do terrible things to stock timing chains. If your friend fits anywhere in these catagories, I would advise him to use a roller chain setup.

 

Well, it's not a race car, not even a high-rpm car. There is a tendency in here to use too stiff valve springs, because most of the engine builders are racers and they may err on the stiff side on street engines too.