WTF? Installed cam dot to dot...#1 at TDC???
03-20-2004, 03:10 AM
#1
WTF? Installed cam dot to dot...#1 at TDC??? Common sense tells me that when the #1 piston is at TDC, you can line the dots on the timing gears up and you'd be all set....meaning that #1 would be at TDC and 'firing'.
But why on LS1s is TDC on #1 actually the beginning of the intake stroke? #6 is actually firing, not #1.
When #1 is firing, the dot on the crank sprocket is straight up as well as the dot on the cam sproket...correct?
But why on LS1s is TDC on #1 actually the beginning of the intake stroke? #6 is actually firing, not #1.
When #1 is firing, the dot on the crank sprocket is straight up as well as the dot on the cam sproket...correct?
03-20-2004, 07:41 AM
#3
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time it with the dots looking at each other ( crank up - cam down ) and the crank seinser will take care of timming go to ls1howto.com and look at cam install and in that is info as to which piston is up at each 90 deg of crank turning , good luck Johnny
03-20-2004, 08:02 AM
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It's very easy to get it timed backwards. I've done it before. Every since when installing the cam, I watch the #1 intake rocker and when it closes you know when the piston get to the top, your at TDC. I still like to use a TDC stop tool to get it perfect.
03-20-2004, 08:52 AM
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Originally Posted by Reckless
Yes....the dots actually look at each other. Cam dot at 6 o'clock and crank dot at 12 o'clock.
03-20-2004, 10:59 AM
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https://ls1tech.com/forums/forced-induction/144540-cam-install-question-dot-dot-1-exhaust-compression.html
This has come up a bit....view this thread for more info...but basically the same info.
This has come up a bit....view this thread for more info...but basically the same info.
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03-20-2004, 11:38 AM
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Lots of folks know this, but just to remind everyone. A 4 stroke engine has the piston at TDC TWICE during each power cycle (i.e. the crank makes 2 revolutions). One on the Compression/Power stroke (cylinder firing, both valves closed) and on the Exhaust/Intake strokes (one or both valves open, another cylinder firing). If you get the piston to TDC, make sure both valves are closed to be on the right stroke. Then dot-to-dot or degree the cam.
03-20-2004, 11:41 AM
#9
Originally Posted by driftpin
It's very easy to get it timed backwards. I've done it before. Every since when installing the cam, I watch the #1 intake rocker and when it closes you know when the piston get to the top, your at TDC. I still like to use a TDC stop tool to get it perfect.
If the dot on the crank gear is straight up and you line the dot of the cam gear up to it, then it's good to go. You cannot be "180° off"....you cannot be "360° off"....the cam dictates the strokes (compression intake exhaust), not the pistons...not trying to rip ya one here, but how can it be timed backwards?
I always assumed that when #1 was at TDC and the dots were aligned, it was firing....but after sitting down and drawing a picture of what is really happening, with valve events and all, I see that #6 is firing and #1 is really starting its intake stroke. I just found it odd...but I am confident it's right because it can't be wrong :-) Later guys!
-Mike
03-20-2004, 11:47 AM
#10
One last thing...
When I was tightening the rocker arms, I did it the way the Helms manual says (I did it this way last time and I like to do it this way). Well, it says with #1 at TDC, tighten exhaust rockers 1 and 7...etc etc...
When I do that, the valve of the rocker I am tightening opens slightly as I torque the bolt. Is that because of the 4° of advance ground in the cam? Or is that from lifter pump-up? Ideally, I wanted the valves closed anf the lifters on the cam's base circle when I tighten the rocker bolts, so I found it strange that the valves opened just a tiny bit when I did it the way the Helm's manual says...it didn't do that last time and the only difference now is that this cam has advance ground in...it's the only explanation I can think of...
??
When I was tightening the rocker arms, I did it the way the Helms manual says (I did it this way last time and I like to do it this way). Well, it says with #1 at TDC, tighten exhaust rockers 1 and 7...etc etc...
When I do that, the valve of the rocker I am tightening opens slightly as I torque the bolt. Is that because of the 4° of advance ground in the cam? Or is that from lifter pump-up? Ideally, I wanted the valves closed anf the lifters on the cam's base circle when I tighten the rocker bolts, so I found it strange that the valves opened just a tiny bit when I did it the way the Helm's manual says...it didn't do that last time and the only difference now is that this cam has advance ground in...it's the only explanation I can think of...
??
