engine trouble need help!
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Joined: May 2011
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Only reason I ask is because if my valve train is not rIght and the computer sets idle at 1000 to set sync to eliminate valve train slop wouldn't I get an inaccurate sync setting with my current valve train or am
I totally wrong
I totally wrong
Legend
Joined: Jul 2007
Posts: 7,843
Likes: 13
From: DFW, Texas
By the computer, do you mean the PCM or the Scanner sets it to 1000?
All valvetrains have slop in them at low idle, even the stock valvetrain on a new engine. That's the way it is when using hydraulic lifters, loose nylon coated timing chains timing chains, etc.
The only way to minimize it is to run it a bit faster to get the oil in there and not allow worn parts (like the timing chain) to slip backward even a little bit.
For instance, when I first bought the JP Performance timing chain set I currently run, it was so tight I could barely get the cam gear onto the cam with the chain on it. I had to use the mounting bolt to walk it onto the cam. When I checked fuel sync that time, it stayed solid on one number, with maybe a minor blip to the next closest number. There was literally no slop at all. After running it for about 20,000 miles, it's loosened a bit, but not that badly. I have a chain tensioner on there now, and that keeps it pretty darn tight. Timing only jumps by about 3* total swing. so 1-3* bouncing is roughly 2, and it typically sticks longer on the "true number", than the others.
You are looking to set fuel sync, but setting fuel sync will only be easiest to set if you replace the timing chain and make sure the lifters are fully pumped up. If you aren't doing those 2 things at least when you swap your rocker arms, don't bother waiting, just do it. If the timing chain is getting replaced, it will definitely help zero in on the number easier.
The rocker arms you are purchasing aren't going to make a difference in valve train slop in this example. They will track very true and straight across the valve tip, due to their design, but they aren't going to compensate for a sloppy chain, deflated lifters, or the incorrect sized pushrods.
All valvetrains have slop in them at low idle, even the stock valvetrain on a new engine. That's the way it is when using hydraulic lifters, loose nylon coated timing chains timing chains, etc.
The only way to minimize it is to run it a bit faster to get the oil in there and not allow worn parts (like the timing chain) to slip backward even a little bit.
For instance, when I first bought the JP Performance timing chain set I currently run, it was so tight I could barely get the cam gear onto the cam with the chain on it. I had to use the mounting bolt to walk it onto the cam. When I checked fuel sync that time, it stayed solid on one number, with maybe a minor blip to the next closest number. There was literally no slop at all. After running it for about 20,000 miles, it's loosened a bit, but not that badly. I have a chain tensioner on there now, and that keeps it pretty darn tight. Timing only jumps by about 3* total swing. so 1-3* bouncing is roughly 2, and it typically sticks longer on the "true number", than the others.
You are looking to set fuel sync, but setting fuel sync will only be easiest to set if you replace the timing chain and make sure the lifters are fully pumped up. If you aren't doing those 2 things at least when you swap your rocker arms, don't bother waiting, just do it. If the timing chain is getting replaced, it will definitely help zero in on the number easier.
The rocker arms you are purchasing aren't going to make a difference in valve train slop in this example. They will track very true and straight across the valve tip, due to their design, but they aren't going to compensate for a sloppy chain, deflated lifters, or the incorrect sized pushrods.
Last edited by aim4squirrels; Aug 5, 2011 at 08:57 AM.
