timing set issues
Thread Starter
Instructor
Joined: Dec 2008
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timing set issues
Well, just tried my 3rd timing set and still there is too much slack in the chain. Someone told me there is a possiblity that it has been lined bored.
1. what is line bored
2. where do i find a timing set to fit a line bored 350
1. what is line bored
2. where do i find a timing set to fit a line bored 350
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
Line bore is the main bearing journals being cut back to get a straight line for the crankshaft to spin in. I highly doubt the a line bore will loosen a chain much. How much slack do you have?
Le Mans Master
Joined: Apr 2006
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.005 and .010 undersized timing sets for aligned bored blocks. 265 to 400 engines
#3100-5 = .005
#3100-10= .010
Last edited by Little Mouse; Sep 19, 2011 at 03:34 PM.
Le Mans Master
Joined: Sep 2004
Posts: 5,116
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From: Livonia MI
I agree, as line boring is similar to rod big end re-sizing. The bearing cap mountings are cut down maybe .002", then honed back to spec sizing. Assuming you're sharing equal material from both block and caps, maybe .001" off. When you think about it, if much off, the harmonic balancer would never seat properly in the front main seal. If you've got a problem with center to center distance between cam & crank, maybe cam bearings. Not sure what the proper C to C distance is, but would probably be a good measurement to start with. If it is cam bearings, you're valve train pre-loads likely off too.
Drifting
Joined: Aug 2005
Posts: 1,682
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From: League City TX
Race Director
Joined: Apr 2000
Posts: 17,676
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
I agree, had my 406ci done and didn't notice any difference in timing chain slack. Now if someone did a hack job on the line boring then maybe, but done right you should be OK. How much slack is there ?
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Le Mans Master
Joined: Apr 2007
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From: Graceland in a Not Correctly Restored Stingray
If you're talking about a dual floating idler gear drive such as the Pete Jackson (BTDT) the self-adjusting design allows some margin, but even they need a few thou clearance. Fixed single idler gear drives require very precise fitting, and the good ones aren't exactly cheap (BTDT too).
Drifting
Joined: Dec 2005
Posts: 1,360
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From: NORTHEAST
When line boring you should not be cutting the block side, So far we have never cut the block side, When we line hone we cut the caps appox. .003 then align hone and in a perfect world we should only be changing the center to center line .0015
You may want to check the cam bearings for wear! Also if the cam bearings have been replaced the factory cam to crank center to center bores may off as we have seen them off .016 before.
That being said GM line bores the cam tunnel with the cam bearings installed to correct for their misalignment issues.
You may want to check the cam bearings for wear! Also if the cam bearings have been replaced the factory cam to crank center to center bores may off as we have seen them off .016 before.
That being said GM line bores the cam tunnel with the cam bearings installed to correct for their misalignment issues.
Thread Starter
Instructor
Joined: Dec 2008
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update..chain is on, but somehow during installation the timing mark on the cam gear moved and is over the edge of the woodruf key is this too far? do i have to remove and do again? (woodruf key is on top of crank now.)
Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
You really need to get the timing marks lined up, so probably back to pulling the cam gear again. I always dail my cams in with a degree wheel and a few other tools and information. Can tell you it's not really visible installing a 5 degree offset key, so if you can visibly see things off, not good. Sounds like your centerline is maybe .002 off, and you installed a .005 chain. That may not be the greatest idea either.