hello every one not trying to make this into a all out brawl. but i recently instaled a distributer on my truck and ran it pretty rough being stupid in the back woods of the wood. and then decided to upgrade to a electronic dist. single pick up. and with the HEI. 4-pin . now for some reason when i put the timing gun on the balancer the tdc mark is jumping almost 10 - 15 deg. + or -.. every one i talk to around here says replace timing chain. so just wondering what every one on here thought . and prior to running the engine really hard. the timing light was a little jumpy but not as jumpy as it is now. thanks. and if it the timing chain and sprockets. is it as easy as pull off and install or are there lots of bumps and curves im going to encounter. thanks.

well seems like no one can help. lets go this route. has any one run into problems with the timing chain on a 225 /6 . either jumping teeth or excessive wear. and if so does any one have any pointers. thanks.

Heck. We're out working on our cars!

If you haven't done a timing set, it's probably due. Are the bushings in the distributor you installed in good shape? Setting it with the vacuum advance unplugged, right?

Could well be a loose chain. It may also be a loose mechanical spring post. Make sure the springs don't unload and allow the weights to bounce around.

If the throttle plate is open a bit too far, the vacuum advance can cut in and out. This would make the timing jump all over the place.

A few thoughts.

CJ

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Part of Tyrde-Browne Racing

Does the engine run better with electronic dist?

If timing is more "jumpy" after dist repl then it might be your dist. Pop the old unit back in & recheck. Look for wear in dist shaft and drive gear teeth(it's plastic after all). Also check for loose dist pickup coil or vac advance.

With dist in eng, gently twist the ign rotor with your fingers. It will be "solid" one way & "springy" the other - as it loads the mechanical advance. There should be almost no loose twist between the solid & springy points.

To check your timing chain, you need a good (not sloppy) dist in the eng & some way to slowly move the crank pulley by hand. If you can use the fan blades & alt belt - then great. Most /6 didn't have a center crank pulley bolt so you might have to loosely screw a couple bolts (3/8 or 5/16 course thread) into the smaller holes of the pulley & use a pry bar to spin the eng over.

Now turn eng clockwise to bring the crank pulley to TDC & mark the dist housing where the rotor tip is pointing. SLOWLY move the crank counter clockwise until the rotor just starts to move (you are taking up the T'chain slack). Measure how far the TDC mark on the crank pulley has moved.

1/8" or less - dude, you're golden ; 1/8-1/4" - eh, so-so ; over 1/4" - it's time to consider doing a chain.

Some tips:
you really want (need) a puller AND installer to remove & refit the crank pulley. The hole in the crank ( for the bolt that likely ain't there) is a 3/4 fine thread. Trying to beat the pulley on with a hammer don't work too good (ask me how I know).
You can probably finagle the timing cover off without pulling the oil pan, but you probably can't get it back on (without big oil leaks afterwards) unless you drop the oil pan - & that ain't no fun.

Timing chain condition depends on what the engine was originally. Most OE truck /6 had iron or steel chain sprockets & were pretty durable. I don't remember if passenger car eng had the crappy plastic & aluminum cam sprocket that so many car makers used in the 60's, 70' (&80's!)

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63 Valiant Wagon
225 - 4 bbl

A loose chain won't make the timing jumping 10*-15*, maybe 1*-2*, not 10*-15*. The chain will always be snug from the load the lifters put on the cam and the crank pulling on the chain at twice cam speed.

First verify the timing light is good on another vehicle, then look at the dist for a problem. Next I'd look at missing or weak advance springs. If it only has the one light spring on it, it may not be able to hold the weights steady at idle, allowing them to bounce around. Make sure the shaft/bushings aren't worn and the advance plate isn't flopping around. A loose pu coil and vac adv can have already been mentioned. It could also be an ECU going bad except normally they either work or they don't.

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Slant Cecil

u guys are saints. i have noticed alot of free play when i have the dist. cap off and rotor installed. when i put the engine at TDC #1 compression. i turn the belts in opposite running direction and have i would guess a little less than 1/2 inch. havent actually put a measuring tool to it yet but i will tomorrow morning. . well i guess i gotta check the throttle plate then the distributor it self. ill double check with a 6 inch rule. thanks for all the info . and hope you all have a great sunday. i know ill be under the hood.