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Discussion Starter #1
Hey i have a question for anyone with an answer. I have a k20z1 that i boosted. It was boosting for a while at 15lbs and then it overboosted blew a head gasket and ran more and more like crap until finally it didn't run well at all. I changed the gasket put studs in but it still is not running well. The only thing that i don't think is right is the timing chain. I've set and re set the timing several times and i still can't get all the marks to line up perfectly. I can put everything like it says to do and then when i turn it over it never lines up perfectly. Anyone had this problems or had a stretched chain give them this problem and give them a running problem. Please help thanks
 

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Hey i have a question for anyone with an answer. I have a k20z1 that i boosted. It was boosting for a while at 15lbs and then it overboosted blew a head gasket and ran more and more like crap until finally it didn't run well at all. I changed the gasket put studs in but it still is not running well. The only thing that i don't think is right is the timing chain. I've set and re set the timing several times and i still can't get all the marks to line up perfectly. I can put everything like it says to do and then when i turn it over it never lines up perfectly. Anyone had this problems or had a stretched chain give them this problem and give them a running problem. Please help thanks
You are not the only one with this problem. I ran into the same issue, I personally think it should be mentioned in the helms or something. When I changed cams I couldnt get the crank marks to line up perfectly, it was always a 1/3 tooth off. It drove me crazy and I started to suspect that my chain had stretched. I put everything together and it ran fine no check engine lights. A few weeks ago I got a different bottom end, new timing chain etc. Basically I swapped heads, compared my old chain with my new one and they were exactly the same length. Assembled the motor and re-did the timing with the new timing chain and sure enough same exact issue with the timing.... the crank seems to be advanced slightly.
 

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was the head milled, or block decked?
AFAIK my head was never taken off the block, unless it was done in Japan...
Even if the head was milled 20 thous, the chain length would be "altered" by 40 thou, which is about 1mm, not enough to cause such a drastic effect on timing. Even then its not as straight forward as that... the chain length has less effect on the whole timing setup, its the slack on the intake side... almost as though the intake side chain guide isnt in the correct position. Basically from a tooth on the intake cam gear to a tooth on the crank sprocket, the chain distance must be a multiple of the length of an individual link. I have found that it isnt hence when you rotate the crank after setting timing, it moves slightly taking the slack away and then the whole system rotates together. I think Talonracer has the same issue before. You might want to PM him
 

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Also, if you look in the helms manual they show the method to set timing and it maybe just me but if you look at the arrow on the block it is NOT pointing directly in the middle of a link of the oil pump chain(ie its not pointing at the punch mark straight on), its slightly behind the middle of the link.
 

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we had that problem last night. I swear to god we redid that SOB 20 times before calling it. It looks so close but just not there. But we'd move the chain over 1 tooth and it was way off. Yet it never really looked perfect. I have yet to put the engine it yet but I'm glad I saw this post. Makes me feel a little better about it now. :up:
 

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we had that problem last night. I swear to god we redid that SOB 20 times before calling it. It looks so close but just not there. But we'd move the chain over 1 tooth and it was way off. Yet it never really looked perfect. I have yet to put the engine it yet but I'm glad I saw this post. Makes me feel a little better about it now. :up:
Are you locking the cams in place when you do this? I ask because I can nail the timing on the first try, every time. I am personally dubious about "chain stretch" because even if the chain did stretch (which I don't think it does), there is enough travel in the tensioner to accomodate that.
 

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The chain will stretch/wear considerably. With 120K on my A2 I changed the chain, I held the new chain and old chain up together and the old chain was a full width of a link below the new chain.

The majority of times that the timing will not set properly at the cams, the chain is a half link off on the crank sprocket or the chain has stretched.
 

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Discussion Starter #10
Ok so i got mixed signals from everyone here. I did lock the cams lined up the crank arow to arrow. But the chain on with the colors on the chains and installed the tensioner. When i turned it over once and lined the crank up it looks about a half link off. I'm about to buy a new chain and see if theres a difference do you tihnk this would cause a running issue at all? I know dohc engines are picky about timing.
 

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I would also consider changing the intake side guide for a new one. Also make sure the key for the crank sprocket is ok/no wear.
 

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Pepsi Soprano
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what he^^^^^^^^^^^^ said
btw where in upstate ny are you im in monroe
 

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chains do stretch i have seen a pic of the comparison of the stretched chain wit the new one and itswas stretched alot and the car it came off of was completely stock if im not mistakin been awhile since i saw that thread
 

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what he^^^^^^^^^^^^ said
btw where in upstate ny are you im in monroe

Up in the Catskill mtns. I live in a very small town, single lane bridge entering town and the postoffice is an addition to the postmasters double wide trailer........LOL, redneck central!
 

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Pepsi Soprano
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Up in the Catskill mtns. I live in a very small town, single lane bridge entering town and the postoffice is an addition to the postmasters double wide trailer........LOL, redneck central!
kinda like where i live for halloween i wore a mullet wig to a party
and noone thought it was cool...lol
 

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Discussion Starter #16
The keyway is perfect still i ain't got no wear on that idk what to think the intake side guide don't look bad either so idk what to think about it all. I'm going to lock the cams and put it back together and load a new program on my computer and see if it runs any better if that doesn't work i guess i'm gunna lose my mind or rebuilt the engine and start a new.
 
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