I did not. I just went "dot to dot"



timing marks aligned.

https://farm5.staticflickr.com/4522/...1c3cd817_z.jpg

Is it possible to time these motors 180* out? After verifying the timing marks were lined up with cyl 1 at TDC, i started to do some investigating.

The cam gear turns 1/2 turn for ever 1 turn of the crank.

Both valves are closed, cyl 1 at TDC, Cam gear mark at 6, crank gear mark at 12. Dowel peg for cam at 3.

And now we start to turn the crank and watch the valves

-At say 9 o'clock(Cam gear) the intake valve has completed its opening and closing cycle, the crank is at 6 completing its Intake Cycle.

-With the Cam at 12, Both valves are closed. Crank is at 12 as well, finishing its compression cycle.

-Cam at 3, the valves are still closed but the exhaust valve is just at the start of its cycle. The Crank is at 6, just finishing its power stroke.

-Cam returns to 6 after finishing the exhaust valve opening and closing, the crank is back at 12, after completing the exhaust stroke.

So going off this info, i have the motor timed at TDC of the start of a new cycle. Not at TDC on the at the end of the compression cycle. Is that were it is supposed to be timed at? or am i correct were its at.

I was going to post yesterday that on the SBC/BBC the dots together means TDC for #6, but it doesn't really matter either way. When you rotate the crank two times then you have the cam gear dot at the top and you're at TDC #1, I am pretty sure the LS is the same. I just pulled my timing set off my 5.3 so I can't double check, but logically it seems the same. The crank doesn't do anything but move the pistons up and down, it's the cam that determines the valve timing.
The only other variable is the cam sensor, and then you would be 180 degrees out if the dots both need to be up

I'm not following you, it all sounds normal :shrug:

Stupid question, maybe... but maybe the PCM needs a crank relearn?

Ive read that its it doesnt matter if it is 180 out. And i dont understand how it would not matter. The cam is ground a certain way, so say at 45 degree is supposed to be beginning to open the exhaust valve on cyl 1, if i have the cam in 180* out, at 45* the cam it would be reading what is supped to be at 270*. Thus rendering the valves opening in closing all out of whack. It makes sense in my head but i struggle to relay what i am thinking

Piston 1 TDC on compression stroke (Valves closed), line up dot to dot. Sounds like that is what you did.

Reluctor look OK and sensors are all happy? If computer doesn't know where crank/cam are, it will cause issues.

The piston is at TDC twice for every rotation of the cam. 1 time at the start of the 4 stroke cycle/end of old cycle, 1 time at the halfway threw at the end of the compression stroke/start of power stroke.

When the timing gears are Dot to Dot it is TDC at the end of the cycle/start of new cycle. When the timing gears are both Dot at 12, it is at TDC, but the cam as at the end of the compression stroke/start of power stroke.

Which TDC should it be timed at ?

Negative, Piston 1 TDC after exhaust stroke, valves closed, reading to start next cycle.

The piston goes up and down, it doesn't give a **** if you are calling it compression or power stroke. The cam controls the valve train timing. So long as you install the cam dot to dot or 180* from that as bear was saying, the motor will operate correctly. We don't have a dizzy to worry about timing here. I also believe with the dowel, you can only install the cam correctly. I haven't done an ls cam swap so I don't know. Dot to dot as you did should be good.

Disregarding fueling and spark, I’m was getting at the compression thing.

I’m not sure what you would call the shape of a cam lobe, like a acorn almost. So say the top of the accord is should be at 3 o’clock, which would yield both valves closed. If the cam is flipped 180, then the tip of the acorn shape would be pushing the lifter up, opening the valve. And if the valve is open, I’m not gunna have compression

There is a dowel on 3-bolt style cams that only allows the timing gear to be installed 1 way. I think there is only a dot on the one side (facing you) of the cam, so you should have correct if you see dots lined up. If you installed with the timing dot facing the motor then I think you could have been 180 out.

http://i2.photobucket.com/albums/y20...heck002iv1.jpg

What were the symptoms again?

Hard start, popping/backfire when started, has backfired threw intake, lacks compression

So it’s not possible to install cam gear backwards? I was questioning that today.

It's possible, but the way you have it is correct. I have the same cam gear on a lamp and just checked it only has the dot on one side

The only way this would work like you think would be 90 out. Like it was said, the piston goes up and down, it doesn't know or care what the valve events are. As kirk clarified and I suspected, you can only install the cam one way. I would try backing off of the lifter preload if you haven't already. You can also try a few drops of oil into one cylinder and see if the numbers on that cylinder improve. You could also use a leak down tester on each cylinder and see where the air bleeds out from. Hissing throttle body? Intake valve/timing issue. Exhaust? Exhaust side. Crankcase? Bottom end. Keep that rain dance going!

Have we completely ruled out incorrect pushrod length? I went through this same issue with a TSP cam about a decade ago. I think I have a pushrod length checker around here somewhere if you need me to begin the hunt.

did a leak down test last night on cyl 1. did it 4 different variations as youll see below.

Dot to dot, push rods installed. rockers not torqued but seated onto the rocker tray.


[url=https://flic.kr/p/DjzwnG]https://farm5.staticflickr.com/4545/...5e8c6de0_z.jpg



cam gear at 12, crank gear at 12, pushrods and rockers same as previous.

[url=https://flic.kr/p/21sghD2]https://farm5.staticflickr.com/4547/...54a4f98f_z.jpg

Dot to Dot, no pushrods or rockers.

[url=https://flic.kr/p/21sghzp]https://farm5.staticflickr.com/4544/...ec4a99d4_z.jpg

12 and 12, no rods or rockers.

[url=https://flic.kr/p/21pxqxL]https://farm5.staticflickr.com/4555/...5d06a776_z.jpg

All 4 tests pass. Air could be heard hissing from the crank case(i dont have the timing cover on) but the gauge says its only 14-16% loss, which passes. unless im understanding it wrong.

When the rockers were bolted down, were the plungers collapsed? If your pushrods are a bit too long there might be enough 'slack' in the plunger travel to hide it when there's no oil pressure.

A compression test (not a leakdown) will show that. If your compression test is low when the rockers are bolted down and higher when you back off the bolts holding the rockers down, that means you have too much preload.

Yes, the lifter deff collapsed a bit.

What tune are you trying to run this on?

Started from nothing.

If you upgraded the MAF from 78 to 85 doesn't it need to be tuned for that?

I would throw kirk's old tune at it if he has it still.