Chevy 305 Timing Chain Question.

I have a high mileage (300k) 305 and I am in the process of replacing the timing chain. I have the cover off and indeed the old chain has some play in it.
How important is it to replace the crankshft sprocket? FWIW neither sprocket really shows any wear on the teeth, although the chain is stretched.
I lined everything up as best I could and marked with paint but even with a 3 jaw puller, the crank sprock will not budge.
I think I just might change the cam sprocket (the big one) and leave the crank sprock alone before I break something.
Bad idea? Opinions? Advice?
--
Sammy Lister
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You are on the right track, don't stop. YES in my opinion you SHOULD change the cam sprocket. MOST of them have nylon teeth on a metal gear and if it has worn enough for the chain to be loose, you should change it.
Look on the crank gear, which is solid steel, and unless the chain has worn down into the steel teeth or groves excessively, you should be okay in reusing it.
Be sure and replace the front seal in the timing cover. You will see a small groove cut around near the end of the crankshaft where the old seal rubbed on it. Hopefully the new seal in a kit will have a "double lip" seal in the kit.

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IMHO, when changing any chain you can almost bet the sprocket is worn too which will result in premature wear on the new chain. For the low price of a crank sprocket you can have peace of mind.
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Yes, you will break your hands. It takes a good impact gun to pull the crank gear. As long as it is not worn-out (sharp-pointy teeth) then you should be okay just replacing the chain & cam gear. (paint? *line up the two dots)

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On Tue, 26 Apr 2005 02:04:47 +0000, scott short wrote:

Thanks to everyone! Paint! Yea, I painted the dots after they were lined up (actually I painted two consecutive teeth and a vertical line through bot gears because I could not get the dots to line up exactly, real close but not exact. I just wanted to make certain I didn't screw up.
Thanks to everyone for the advice! I'm going to leave the gear alone because it does not look worn at all.
Both gears have steel teeth BTW, no plastic on any of the gears.
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Sammy Lister
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On Tue, 26 Apr 2005 02:04:47 +0000, scott short wrote:

Well I got the gear off, replaced both gears and chain. Now I am trying to get the timing chain cover back on. What a PITA!!!!!!!!!!!!!! I've loosend the front oil pan bolts, although the pan seems solid and does not move, I was able to just pull up on the cover and out it came.
Putting it back is turning into a nightmare. It interferes with everything and why on earth is the lip on the bottom so long.
A person could make a fortune selling a 2 piece kit split in the middle so one half hooks into the pan and the other just hooks onto the top.
I've cut a little bit out of the edges of the lower lip ((near the ends where it interferes) and still I can't get the blasted thing in there.
I think I have to remove the bracket that holds the PS pump and alternator and then MAYBE I can squeeze it in there.
One thing that drives me nuts with GM cars is that the engineers always seem to insert curves, elongations and distortions into brackets and things just in order to make it impossible to remove other things. It's like they do it on purpose,
Example?
Look at the plumbing for the air pump. They purposely curve the stainless steel tubes so that they block the spark plug holes making it difficult to sdo plugs. IOW curves in the tubes for no reason other than the interfere with other things.
It's a nightmare.
So any advice on how to get the timing chain cover back on and seated properely in the dual seal on the oil pan?
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Sammy Lister
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It will go on. Use the dowel pins to leverage it on. Did you trim the ends on the metal lip?

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On Wed, 27 Apr 2005 13:09:31 -0500, noname wrote:

Yes I trimmed about 1/8th inch off the tops of the double channel U lip on the cover on each side of it. I figured I would just use extra RTV to make up for it. There was no way in heck I could even get this close without trimming a little metal off. I'm not sure what you mean by using the dowel pins to leverage it?
What I am trying to do is angle it slightly, like maybe 1/2 inch from the engine block on top, get the u lip to seat in the rubber gasket by pushing down and in towards the engine at the same time. I'm having no luck and like I said I have the 4 bolts closest to the front of the engine off on the oil pan, but the pan don't move at all and I can't even see the other bolts let alone remove/loosen them.
What happens is I can usually get one side seated but the other side will push the lip gasket back in towards the pan. IOW I can't get both sides in at the same time.
Any idea why the pan won't move at all?
I would think it should move a little bit with 4 bolts off?
TIA
Sammy
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Sammy Lister wrote:

You've done the right thing by trimming the edges off of the metal lip on the front cover. I always trimmed it so that it is completely gone (flush with the cover) at the end and then gently curves back up to its full width about 3/4" up. Then, install the front pan seal in the timing cover, apply RTV to the pan seal ends (so that you will get a seal at the corner where the front pan seal meets the block), grease the outer edge of the seal (the edge that will mate with the oil pan). Then, start one side, get one dowel just thru a hole on one side, install a front cover bolt in the lowest hole on that side, all you need is a thread or tow. Now, force the cover over the other dowel, and just start the lower bolt on that side. At this point, the lower edge of the front cover will be sticking out. Now you can slowly tighten each bolt and draw the front cover on...."while" pushing the front pan seal into place from below. Just take your time and it will go together. I've done hundreds of them this way. Another little tip, I always trimmed a little bit of the rubber seal off...right at each end...so that it will slip into place a bit easier. The RTV takes care of any possible leaks.
Ian
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Thanks so much Ian and all the others. The advice you guys gave was right on the money and without your help, especially Ian, I never would have gotten this done. It all worked great, I have no leaks and the car is running like a top! Thanks again.
Sammy
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Sammy wrote:

You are very welcome, Sammy! Thanks for posting back about the end result.
Ian
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Thanks so much Ian and all the others. The advice you guys gave was right on the money and without your help, especially Ian, I never would have gotten this done. It all worked great, I have no leaks and the car is running like a top! Thanks again.
Sammy
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