Do Timing Chains Stretch......

[ffej]

on a rebuilt after the first 5k or so..I've got a rebuilt and the idle and missing is bringing me down..It has run awesome and I've checked everything and replaced all the usuall suspects (plugs/wires/ignition mod) I've checked the timing (without a tach) and it seems to be about 5-7 degrees short of the 12 deg. btdc..could this cause stumbel idle? I figured the chain could have stretched seeing it was new and all... :D redface.gif :eek: :rolleyes: :confused:

[ April 19, 2003, 05:19 PM: Message edited by: ffej ]

[andy d]

they stretch but not enough to change the timing. not in 5k was the dizzy clamped down tight?

[Serious Johnson]

Short answer: Yes.

Long answer: Yes, but generally after only long stretches (pun intended) of time. I have not personally encountered a timing chain that stretched significantly in the initial 5k miles. They're metal, and don't react like rubber belts.

Most likely, your ignition timing was either set incorrectly from the get-go, or has for some inexplicable reason (like perhaps a loose clamp bolt) drifted since initial setup.

Remember that ignition and valve timing are different, if codependant things. The only relevant relationship between the two that comes to mind is wear induced lash between the camshaft & distributor gears.

I'd just set the ignition timing again, and see how it holds up. Good luck, and please keep us posted so that we don't remain as goldang ignorant as we are today.

:-

[JeepJerk]

Have seen very poor quality timing chains stretch quite a bit after breakin; check by removing dist cap and turning over motor until you see the rotor turning; should be almost immediately. Then rotate motor the opposite way until you see the rotor move. How many degrees on the cranks did you move the rachet or breaker bar until the rotor moved? Should be **** close to none to maybe 10 degrees at worst ( this would be if you could view the crank from head on looking at the front pulley/damper). any more than that an you may have a problem. Serious Johnson has a good point; inital timing between the cam and crank may have been off from the get go. Carb working properly? Reused dist. with a worn gear? Is the rotor in phase with the coresponding tower on the cap?