LT1/4 Timing chain slack
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 5,589
Likes: 0
From: DrunkDefender
CI 1-2-3-4-5-6-7-8 Veteran
CI-IV AutoX Champ
CI-IV Burnout Champ
St. Jude Donor '07-'10
LT1/4 Timing chain slack
In the middle of a elec water pump install and pulled the timing cover to remove the water pump drive. The current LT4 chain has roughly 30k on it. If I rotate the crank to pull the slack out of the timing chain on the pull side I have right at 1/2" of slack. About every SBC has some slack in it but I couldnt find a spec that specifies how much is too much. Does this seem excessive?
Discuss
mods, I also posted this over in engine mods to get an idea there. Hope you dont mind.
Discuss
mods, I also posted this over in engine mods to get an idea there. Hope you dont mind.
Melting Slicks
Joined: Oct 2006
Posts: 2,238
Likes: 10
From: College Station TX
A lot of LTx's have significant slack in the timing chain. If you're doing an electric water pump, you can run any SBC timing set you want. A double roller will get rid of all the slack, but may require some grinding of the timing cover for clearance.
Advanced
Joined: Feb 2004
Posts: 87
Likes: 0
From: albrightsville pa
I installed a hot cam in my 96 lt4 a few years ago about 24,000 miles and also had alot of slack in the chain, I got a new chain from GM and still had about the same amount of slack, never had a problem.
Le Mans Master
Joined: Jul 1999
Posts: 8,683
Likes: 6
From: Phoenix AZ
You might want to consider going to a nice roller chain setup, either the LT4 Heavy Duty set from GM or the double roller set from Cloyes.
The only problem with the double-roller is that you need to get rid of the crank position sensor gear, which isn't a big deal as all it does is report potential mis-fires.
The only problem with the double-roller is that you need to get rid of the crank position sensor gear, which isn't a big deal as all it does is report potential mis-fires.
Le Mans Master
Joined: Aug 1999
Posts: 7,339
Likes: 137
From: WilkesBarre PA
Mine has a little slack also. I thought of getting this oversized crank gear: http://thunderracing.com/catalog/?ac...vid=4&pcid=222
the next time I'm in there.
the next time I'm in there.
Thread Starter
Le Mans Master
Joined: Apr 2000
Posts: 5,589
Likes: 0
From: DrunkDefender
CI 1-2-3-4-5-6-7-8 Veteran
CI-IV AutoX Champ
CI-IV Burnout Champ
St. Jude Donor '07-'10
Chad, running a cloyes is an option but I'm really on a budget. Its not as if an extra $75 for a stock LT4 will hurt my budget but I'm very very prone to the whole "while you're in there" syndrome. I really just wanted to do the EWP, now that I'm this far in I'm looking at cams also 
Ed, there was alot of slack in the stock one when I took it off during the hotcam install. I figured [hoped] a new stocker would last at least as long. I think my stock one is still good but wanted to discuss it a bit.
Zix, the cloyes is on my short list. I dont want to have the crank sensor programmed out just yet though.
Rich, I saw that gear earlier. Its an alternative if I keep the stock set up but in the future I plan to build another motor so who knows.
I'm really just wanting this motor to last another couple of years at most and maybe another 20k miles. I also want to get the car back on the road ASAP. Ordering another chain means another week of downtime.
Ed, there was alot of slack in the stock one when I took it off during the hotcam install. I figured [hoped] a new stocker would last at least as long. I think my stock one is still good but wanted to discuss it a bit.
Zix, the cloyes is on my short list. I dont want to have the crank sensor programmed out just yet though.
Rich, I saw that gear earlier. Its an alternative if I keep the stock set up but in the future I plan to build another motor so who knows.
I'm really just wanting this motor to last another couple of years at most and maybe another 20k miles. I also want to get the car back on the road ASAP. Ordering another chain means another week of downtime.
Last edited by Dr. Evil; Apr 1, 2008 at 10:33 PM.
Safety Car
Joined: Feb 2004
Posts: 3,786
Likes: 0
From: Minneapolis MN
When I had my hot cam installed the shop doing the work informed me ahead of time that the LT4 timing chains were junk and said he would recommend replacing it since it was all apart. Sure enough it was all stretched out only 38K on the clock. He replaced it with LT4 super duty.
Pro
Joined: Sep 2001
Posts: 744
Likes: 2
From: Homestead Florida
Hey Dr Evil
Well, I bought a 96 lt4 (also 38k miles) to replace my blown lt1 (automatic) but wanted the hotcam in it. When I pulled the timing cover, I was disappointed to see that the lt4 chain had significant slack at this low mileage....very similar to older chevy engines with worn out timing chains that I always replaced.
After listening to many recommendations to change the timing chain and reviewing the rediculous price of a stock lt4 chain, I did more research on this and other forums and found that even a brand new one will have a lot of slack in it.
Bottom line is that I decided put the old one back in theorizing that the stock lt4 timing chain should go for at least 100k miles, and since I only drive it about 10k miles a year, this chain would last me another 6 or 7 years assuming it had only 38k miles as the seller stipulated.
Btw, I flog my engine regularly to the rev limiter of 6800, and Yes, I do say a small prayer each time. The first few times I did it, I thought sure as hell that worn out chain was going to give, but 15k hard miles later, and I am glad I saved? the money. Once you have it back together, you won't remember all that slack it had. Near as I could tell, they all have it. I have to say, it is an uncomfortable feeling and sight to see how sloppy that stock chain is, and it is hard to put it back together thinking you are skimping on this part. But really, I (now) don't believe there is anything wrong with the chain, but of course that's not a scientific statement.
I do recall someone saying that the chain was designed with a lot of slack because of the inherent front cam bearing wear in the LtX. I can't see any other reason why older small block motors don't seem to have this problem. My lt1 (that blew due to overheating) did have significant front cam bearing wear and a very sloppy timing chain at 70k miles.
So, my vote is to put it back in and be done with it. This chain looks weaker than the lt1 chain, but from what I understand is supposed to be much more durable. You can always find a way to throw more money at a motor that youre building but my happy medium was to replace the wp and opti with new units and hope gm didnt short change me on the chain.
By the way, be sure to check those timing marks by rotatiing the motor over a few times and making sure they still line up after reinstalling it. Even though it looks perfect, and aligned, it may not be. The dilemma is that you (rather me) are not sure to install it with slack on the leading and trailing runs in the chain or take slack completely out of one side to install it. Problem is it will install both ways and will look right until you rotate the engine a couple times and oooops, timing marks don't line up anymore.. I don't recall which one I did the first time, but it was off 1 tooth, verified by rotating the engine over.
hopefully someone will discuss noninterference vs interference with the hotcam installed. I don't know if pistons and valves would crash in the event of a TC failure.
good luck
Sam
Well, I bought a 96 lt4 (also 38k miles) to replace my blown lt1 (automatic) but wanted the hotcam in it. When I pulled the timing cover, I was disappointed to see that the lt4 chain had significant slack at this low mileage....very similar to older chevy engines with worn out timing chains that I always replaced.
After listening to many recommendations to change the timing chain and reviewing the rediculous price of a stock lt4 chain, I did more research on this and other forums and found that even a brand new one will have a lot of slack in it.
Bottom line is that I decided put the old one back in theorizing that the stock lt4 timing chain should go for at least 100k miles, and since I only drive it about 10k miles a year, this chain would last me another 6 or 7 years assuming it had only 38k miles as the seller stipulated.
Btw, I flog my engine regularly to the rev limiter of 6800, and Yes, I do say a small prayer each time. The first few times I did it, I thought sure as hell that worn out chain was going to give, but 15k hard miles later, and I am glad I saved? the money. Once you have it back together, you won't remember all that slack it had. Near as I could tell, they all have it. I have to say, it is an uncomfortable feeling and sight to see how sloppy that stock chain is, and it is hard to put it back together thinking you are skimping on this part. But really, I (now) don't believe there is anything wrong with the chain, but of course that's not a scientific statement.
I do recall someone saying that the chain was designed with a lot of slack because of the inherent front cam bearing wear in the LtX. I can't see any other reason why older small block motors don't seem to have this problem. My lt1 (that blew due to overheating) did have significant front cam bearing wear and a very sloppy timing chain at 70k miles.
So, my vote is to put it back in and be done with it. This chain looks weaker than the lt1 chain, but from what I understand is supposed to be much more durable. You can always find a way to throw more money at a motor that youre building but my happy medium was to replace the wp and opti with new units and hope gm didnt short change me on the chain.
By the way, be sure to check those timing marks by rotatiing the motor over a few times and making sure they still line up after reinstalling it. Even though it looks perfect, and aligned, it may not be. The dilemma is that you (rather me) are not sure to install it with slack on the leading and trailing runs in the chain or take slack completely out of one side to install it. Problem is it will install both ways and will look right until you rotate the engine a couple times and oooops, timing marks don't line up anymore.. I don't recall which one I did the first time, but it was off 1 tooth, verified by rotating the engine over.
hopefully someone will discuss noninterference vs interference with the hotcam installed. I don't know if pistons and valves would crash in the event of a TC failure.
good luck
Sam
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Burning Brakes
Joined: Nov 2004
Posts: 800
Likes: 3
From: Port Orange FL
When I did mine I couldnt believe how much slack was in the chain at 70K. I went out and bought myself a new one, stuck it on, and guess what? It had just as much slack in it as the one I took off. 
Roy
Roy
Melting Slicks
Joined: Oct 2006
Posts: 2,238
Likes: 10
From: College Station TX
I have a spare over-size LT1 crank sprocket. Long story short, I'm an idiot and bought an LT1 sprocket to go with an LT4 chain (for those that don't know, that combo doesn't work).
I'll let it go cheap if anyone wants it. Brand new in box.
I'll let it go cheap if anyone wants it. Brand new in box.
Advanced
Joined: Feb 2004
Posts: 87
Likes: 0
From: albrightsville pa
Hey Dr Evil
Well, I bought a 96 lt4 (also 38k miles) to replace my blown lt1 (automatic) but wanted the hotcam in it. When I pulled the timing cover, I was disappointed to see that the lt4 chain had significant slack at this low mileage....very similar to older chevy engines with worn out timing chains that I always replaced.
After listening to many recommendations to change the timing chain and reviewing the rediculous price of a stock lt4 chain, I did more research on this and other forums and found that even a brand new one will have a lot of slack in it.
Bottom line is that I decided put the old one back in theorizing that the stock lt4 timing chain should go for at least 100k miles, and since I only drive it about 10k miles a year, this chain would last me another 6 or 7 years assuming it had only 38k miles as the seller stipulated.
Btw, I flog my engine regularly to the rev limiter of 6800, and Yes, I do say a small prayer each time. The first few times I did it, I thought sure as hell that worn out chain was going to give, but 15k hard miles later, and I am glad I saved? the money. Once you have it back together, you won't remember all that slack it had. Near as I could tell, they all have it. I have to say, it is an uncomfortable feeling and sight to see how sloppy that stock chain is, and it is hard to put it back together thinking you are skimping on this part. But really, I (now) don't believe there is anything wrong with the chain, but of course that's not a scientific statement.
I do recall someone saying that the chain was designed with a lot of slack because of the inherent front cam bearing wear in the LtX. I can't see any other reason why older small block motors don't seem to have this problem. My lt1 (that blew due to overheating) did have significant front cam bearing wear and a very sloppy timing chain at 70k miles.
So, my vote is to put it back in and be done with it. This chain looks weaker than the lt1 chain, but from what I understand is supposed to be much more durable. You can always find a way to throw more money at a motor that youre building but my happy medium was to replace the wp and opti with new units and hope gm didnt short change me on the chain.
By the way, be sure to check those timing marks by rotatiing the motor over a few times and making sure they still line up after reinstalling it. Even though it looks perfect, and aligned, it may not be. The dilemma is that you (rather me) are not sure to install it with slack on the leading and trailing runs in the chain or take slack completely out of one side to install it. Problem is it will install both ways and will look right until you rotate the engine a couple times and oooops, timing marks don't line up anymore.. I don't recall which one I did the first time, but it was off 1 tooth, verified by rotating the engine over.
hopefully someone will discuss noninterference vs interference with the hotcam installed. I don't know if pistons and valves would crash in the event of a TC failure.
good luck
Sam
Well, I bought a 96 lt4 (also 38k miles) to replace my blown lt1 (automatic) but wanted the hotcam in it. When I pulled the timing cover, I was disappointed to see that the lt4 chain had significant slack at this low mileage....very similar to older chevy engines with worn out timing chains that I always replaced.
After listening to many recommendations to change the timing chain and reviewing the rediculous price of a stock lt4 chain, I did more research on this and other forums and found that even a brand new one will have a lot of slack in it.
Bottom line is that I decided put the old one back in theorizing that the stock lt4 timing chain should go for at least 100k miles, and since I only drive it about 10k miles a year, this chain would last me another 6 or 7 years assuming it had only 38k miles as the seller stipulated.
Btw, I flog my engine regularly to the rev limiter of 6800, and Yes, I do say a small prayer each time. The first few times I did it, I thought sure as hell that worn out chain was going to give, but 15k hard miles later, and I am glad I saved? the money. Once you have it back together, you won't remember all that slack it had. Near as I could tell, they all have it. I have to say, it is an uncomfortable feeling and sight to see how sloppy that stock chain is, and it is hard to put it back together thinking you are skimping on this part. But really, I (now) don't believe there is anything wrong with the chain, but of course that's not a scientific statement.
I do recall someone saying that the chain was designed with a lot of slack because of the inherent front cam bearing wear in the LtX. I can't see any other reason why older small block motors don't seem to have this problem. My lt1 (that blew due to overheating) did have significant front cam bearing wear and a very sloppy timing chain at 70k miles.
So, my vote is to put it back in and be done with it. This chain looks weaker than the lt1 chain, but from what I understand is supposed to be much more durable. You can always find a way to throw more money at a motor that youre building but my happy medium was to replace the wp and opti with new units and hope gm didnt short change me on the chain.
By the way, be sure to check those timing marks by rotatiing the motor over a few times and making sure they still line up after reinstalling it. Even though it looks perfect, and aligned, it may not be. The dilemma is that you (rather me) are not sure to install it with slack on the leading and trailing runs in the chain or take slack completely out of one side to install it. Problem is it will install both ways and will look right until you rotate the engine a couple times and oooops, timing marks don't line up anymore.. I don't recall which one I did the first time, but it was off 1 tooth, verified by rotating the engine over.
hopefully someone will discuss noninterference vs interference with the hotcam installed. I don't know if pistons and valves would crash in the event of a TC failure.
good luck
Sam
I think all sbc's are interference motors, but if your lucky you'll just bend a push rod
Melting Slicks
Joined: Jun 2000
Posts: 3,215
Likes: 6
From: Tampa Florida
When rebuilding my LT4...I contacted Cloyes directly thru my machine shop and exchanged my std lower sprocket for an oversized.
I don't recall any phone numbers, etc, but it was a specific individual at the time (5 years ago).
Might give that a try...sloppy chains aren't for hipo motors.
I don't recall any phone numbers, etc, but it was a specific individual at the time (5 years ago).
Might give that a try...sloppy chains aren't for hipo motors.
Melting Slicks
Joined: Oct 2006
Posts: 2,238
Likes: 10
From: College Station TX
I just sold my gear on another forum, but here is a link to where I got it:
http://thunderracing.com/catalog/?ac...vid=4&pcid=222
http://thunderracing.com/catalog/?ac...vid=4&pcid=222
