Advice needed - timing chain

[kev2809]

Long story short, I'm replacing an engine on a 96 2500 silverado. going through gaskets and "easy" stuff now that I have the used replacement engine on the stand. while doing the timing chain and cover..when I put the new chain back on, the dots line up on the gears, but the teeth were ever so slightly off. I'm talking like 1/16" or so. the points of the teeth didn't quite line up. is this going to cause trouble? I haven't pulled the distributor at all and probably don't plan to. I did line up the dots when removing the old chain and gear...damn I had hell pulling the cam gear sprocket. my puller kept rotating the engine, so I had to keep taking it off and rotating til the dots lines up, then try again til I finally got it.

[AussieinNC]

The dots on the timing gears are sometimes off just a tad.

So long as the dots line up through the centerline of the cam and crank you will be good.

Note....and so many people make this mistake...

When the dots are placed with cam gear dot at bottom and crank gear on the top, the engine is set to fire on cylinder #6.

When the dots are placed with cam gear at 12 oclock and crank gear at 12 oclock, the engine is set to fire on cylinder #1.

Your choice to remove the distributor and intake manifold, but the end gaskets especially at the rear are the usual upper area leak locations.

Finally when you are installing the ignition leads, dont mix up cylinders 5 and 7....again a common mistake.

Have fun...

[kev2809]

I put everything back together and it's sitting on the stand ready to go in, I just got the old engine out yesterday. but yes, the dots seemed ok, just the corresponding teeth looked a little off. but while putting the harmonic balancer and pulley back and tightening them down, the timing line from the timing cover was a little off on the balancer timing line too, seemed even more than the dots. now, the balancer COULDVE moved while tightening the bolt...but I don't remember checking before putting the balancer on


so..I guess my question is...what IF it's a little off...will it run poorly? I should've taken a picture to show the fraction I seen!

[AussieinNC]

The balancer is keyed to the crankshaft....if it moved during tightening the crank would have moved as well.

The outer ring of the balancers sometimes rotates around a little.

If you want to ensure the timing tab and balancer marks line up correctly you can do a positive stop procedure to index a new line on the balancer.

Purchase yourself a positive stop tool (amazon has them cheap). https://www.amazon.com/ZFLXH-Univers...s%2C101&sr=8-2

Set your engine to what you believe is TDC on cylinder 1 on compression. Look for the vales on cylinder 6 to have exhaust just closing and intake just opening. This is known as overlap.

The tool goes into the number 1 spark plug hole but first turn the crank backwards about half a turn. Screw in the stop tool and very slowly, manually turn the crank clockwise until the stop tool prevents any further crank movement. Take a white marker and mark a line on the balancer at the 0 degree mark on the tab. Now rotate the crank BACKWARDS slowly until you feel it stop again and mark a white line on the balancer. Remove the stop tool and turn the crank clockwise until you can see the two white lines. Measure the distance around the balancer using a tape and make a mark on the balancer at the mid point of the distance. This mark is now your true TDC mark and should be used for timing purposes. Remove the other marks. Take a small file and scribe a heavy line across the edge of the balancer then fill it with white permanent paint.

[kev2809]

I actually bought one of those piston stops years ago...but if I don't really care that the lines line up for physical appearance, is still necessary?

[AussieinNC]

Maybe its me, but I always run the true TDC check and mark the balancer....that way I know the timing line is accurate....

I prefer to do it right the first time....

But its your engine....

[MySons68C20]

Originally Posted by AussieinNC

Maybe its me, but I always run the true TDC check and mark the balancer....that way I know the timing line is accurate....

I prefer to do it right the first time....

But its your engine....

I agree! There is no way to know your true timing unless you use a piston stop to establish TDC.

[kev2809]

Originally Posted by AussieinNC

Maybe its me, but I always run the true TDC check and mark the balancer....that way I know the timing line is accurate....

I prefer to do it right the first time....

But its your engine....

Originally Posted by MySons68C20

I agree! There is no way to know your true timing unless you use a piston stop to establish TDC.

agree with both of you guys, I'll dig out the tool and make a new mark if its off. I'm just trying to understand the physical appearance of the gears and the timing dots to actual timing. I figured since nothing on the inside was removed, and I never pulled the distributor, then technically you can slap a timing chain and gear in any way and still functions the same? man I feel so dumb asking this type of stuff lol

also, on these 5.7 vortecs, they don't have a traditional timing tab. there is a solid line on the timing chain cover, and a solid line on the balancer. I remember my old 305 had numbers in that area, this one does not