how to tell if 1 is in firing position for reassembly

[Powerhouse]

So...i just wanna make sure before i reinstall the timing cover(which I don't know the torque specs for..as well as cam hub and timing gear) that the cam lobes are in correct position with pistons for 1 to fire. The piston is at top of cyl...and the cam lobes on #1's valves are just about to open. On six they are opposite position of 1, so the lobes are pointing away from the lifters....ya dig? is that correct?

[james curl]

No, the lifters should be on the back of the lobes at TDC, lobes pointed down. You want the engine to travel 90 degrees after TDC before the exhaust valve starts to open. Rotate the engine, If either valve on number 1 cylinder is getting ready to open as soon as you leave TDC and start down you are 180 off. The valves on number 1 cylinder should not open until the piston is on the way up after the power stroke, and the exhaust valve will open at that time and remain open until the piston gets to TDC then the intake valve opens on the down stroke and closes on the up stroke to compress the mixture at tdc then fires the mixture., from your description that a valve is getting ready to open on no.1 cylinder it is going into the intake stroke so you are 180 out, as the engine is now it appears that no.6 is at the top of the compression stroke ready to fire. I hope this helps and not muddies the water.

[Merle Coggins]

If you're 180 off, like mentioned, rotate your crank one full revolution and you should have both #1 valves closed. You should have marks on both timing sprockets. If you were to draw a centerline through the cam and crank both marks should be centered on that line. Ususlly I put them together so it's easier to see how they line up,(crank mark facing the cam and cam mark at the crank) but even if the cam sprocket mark is 180 degrees away from the crank, as long as it's on that centerline you're OK. Because if you rotate the crank one full turn it'll put the marks right together. It's a 2:1 ratio. Crank turns 2 rotations for every 1 rotation of the cam.

Merle

[greg g]

Thher are marks on both chain sprockets. Just a small dimple dot, they should be alligned adjacent to each other when 1 is at tdc.

Since you are working with a gasket on the timing cover, you only nee enough torque to begine to compress the gasket, and not so much to wrinkle it between the mounting faces.

First find the one or two that go into the coolant passage and put some thread sealer on them, the tightenthem ot snug in an everyother one rotation or use a star pattern like on lug nuts. After you get them snug, another 1/4 to 1/2 turn should do it.

[Powerhouse]

GREAT thanks guys! I thought i might be off...it was a 50/50 chance...and I'm always on the wrong 50. hahaha.

So lobes pointing AWAY from the lifters is firing=valves closed. COOL...thanks.

[Powerhouse]

SO, WHAT the heck am I doing wrong???? If I am... I tried getting the lobes to point away from the lifters...but the cam gear dot doesn't line up with the main gears dot. It's opposite exactly. here's some pics.

this is lobes 1 and 2 pointing upwards to lifters...not directly at them but to either side

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this is lobes 11 and 12...pointing downwards but to either side

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dots are lined up here...but not when the lobes on 1 &2 valve are pointing down

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[Powerhouse]

I just tried again to make the 1st cylinders respective cam lobes point away from the lifters with the dots facing each other.

WON'T GO...

The cam sprocket can only be bolted on one way. The crank sprocket as well. I don't see how this isn't working....

ARGH! WHAT to do!

[Dodgeb4ya]

Just make sure the cam and crank gear dots line up with a straight edge (across the centerlines of both the cam and crankshaft when properly assembled. You don't really need to care that when the dots are lined up the #1 cylinder cam lobes are up and not at TDC. Most engines have this same design. Number 6 cylinder is on the TDC compression stroke (cam lobes pointing down) with the cam dots lined up-this is normal and correct. Rotate the crankshaft one full rotation (360) degrees to set the engine up to # 1 cylinder to get it to TDC if you want it there for distributor installation and start up. BTW Crankshaft rotates 2 times for every one revolution of the camshaft.

Bob

[james curl]

With the cam as shown in the picture with the lobes pointed almost 180 degrees opposite each other the cam should be in the #6 TDC position. Now rotate the engine 180 degrees in the direction of rotation. The crank should move almost 180 degrees before the exhaust valve, #12 in your picture starts to opening at the bottom of the stroke. If at that time the valve #12 starts to open your starting point was TDC. 0n #6 cylinder. Rotate the engine back 180 degrees in the opposite direction to the point of beginning, now you are back at TDC on #6 cylinder. Remember, the cam moves at 1/2 the speed of the crank. 180 degrees on the crank = 90 degrees on the cam, at that point you should see the lobe on the cam starting to hit the outer side of the head on the tappet to start lifting the #6 exhaust valve, the one you have numbered #12 I think, the last exhaust valve which is the last valve. Valves 1,4,5,8,9and12 are exhaust valves, they are the smaller domed head valves, I think that is how you have them numbered although I think I see an eleven on the #5 intake valve. When you start to rotate the crank the #1 cylinder intake valve should start to open if the #6 cylinder is at TDC, the crank will move 180 degrees before the exhaust valve starts to open on #6. At that point the #1 cylinder intake valve is closing. Another 180 degrees of rotation of the crank should start the #6 cylinder intale valve opening and the exhaust on #6 closing, at that point both valves on # 1 will be closed. Now you are at #1 TDC.

Edited June 1, 2010 by james curl
add details

[james curl]

In my service manual, they show both cam sprockets with th 0's across from each other and states to now adjust the valves on number six cylinder which is at the top of the compression stroke ready to fire the mixture, or #6 TDC. Your engine as shown in your picture with both sprockets timing mark pointing toward each other is number six cylinder TDC according to my service manual.

[Powerhouse]

AH! I see now...the dots next to each other don't mean it's at #1 TDC...just lined up correctly and at 6 TDC. OK...I guess i'm good to go then. Just rotate engine to get 1 at TDC and reinstall the dizzy to position 1. This was seeming to be much harder than it is.

Long weekend with a new kitten...and a sick wife...didn't help my brain much. THANKS GUYS!

That is I f i got this right...if not...I'll just have to shoot something.

Edited June 1, 2010 by Powerhouse

[Dodgeb4ya]

AH! I see now...the dots next to each other don't mean it's at #1 TDC...just lined up correctly and at 6 TDC. OK...I guess i'm good to go then. Just rotate engine to get 1 at TDC and reinstall the dizzy to position 1. This was seeming to be much harder than it is.

Long weekend with a new kitten...and a sick wife...didn't help my brain much. THANKS GUYS!

That is I f i got this right...if not...I'll just have to shoot something.

You've got it now!!

[Don Coatney]

You are making this way too complicated. It appears your cam timing gears are on the money. So, while in front of the engine rotate the crankshaft clockwise until you see the intake valve closing as the #1 piston comes to the top. When it is at the top you are TDC on #1.

[Powerhouse]

Can I still shoot something? hahaha

[Greenbomb]

If it doesn't work, you can shot something out of frustration. If it does work you can shoot something in celebration. Either way, you can shoot something.

[Powerhouse]

HAHAHA...sounds good to me.

I just snapped a cam to block bolt head...Maybe i'll shoot that. drilled it out ok...tapped a star head bit into the drill hole and turn it out...worked so nicely. NOW i'm going to get grade 8 bolts...just because that was so much fun.