Cam Timing

[Dan the man]

I didn't want to highjack the op question on cam timing, but I do have a question about it. When installing a timing chain I always brought up #1 on the compression stroke, turned the cam gear to the 6 o'clock position and the crank gear to the 12 o'clock position, then I installed the distributor with the rotor pointing at the #1 terminal in the distributor cap, I never had any trouble with starting the engine or adjusting the ignition timing. I was always told that putting both gears at 12 o'clock would put the cam a 180* off. I was even told this in tech school. Is the 6 o'clock 12 o'clock method correct? Also, back in those days I didn't degree the cam.

 

[remytherat]

Either way you put the cam in, all you would have to do is flip the dizzy around and the engine will run fine.

 

[Sterling]

I usually put the cam gear at 6 o’clock, and crank gear at 12 o’clock, because it is easier to see if you are a tooth off. Which I think is tdc #6 firing. If you turn the crank 1 turn, the cam gear mark will be at 12 o’clock and #1 firing. This is after degreeing the cam. I degree every one, after finding a couple that were retarded 10* when lining up the marks .

 

[66fs]

I didn't want to highjack the op question on cam timing, but I do have a question about it. When installing a timing chain I always brought up #1 on the compression stroke, turned the cam gear to the 6 o'clock position and the crank gear to the 12 o'clock position, then I installed the distributor with the rotor pointing at the #1 terminal in the distributor cap, I never had any trouble with starting the engine or adjusting the ignition timing. I was always told that putting both gears at 12 o'clock would put the cam a 180* off. I was even told this in tech school. Is the 6 o'clock 12 o'clock method correct? Also, back in those days I didn't degree the cam.

That is how I do it also, then I degree the cam. I just need to know for sure #1 intake lobe is at the right place.

 

[junkyardhero]

i think a lot of folks do the same: initial install dot to dot, then degree to double check and/or adjust.

 

[AJ/FormS]

Because the cam gear turns at half engine speed, It doesn't matter if you choose 6 and 12, or 6 and 6 for to slide the gears on, prior to degreeing.
But before you drop the D in, just make sure you got the right cylinder at TDC compression. And it doesn't even matter which particular Cylinder is at TDC Compression, so long as you put the rotor under a tower, and call that tower by the same number as is the cylinder that is at TDC compression, then wire the cap accordingly. Oh and, the oil-pump drive has to be engaged.
There are only two reasons to do it per the book;
1) the factory precut Ignition wires are pretty short and some cylinders will not fit no matter how you juggle the wires around, and
2) is convention. Down the road if somebody takes the D out and isn't paying attention, then it is highly unlikely that he will get it back together right, cuz he's looking for the rotor to be under a certain tower with #1 at TDC compression.

 

[remytherat]

It's also important to get the distributor in right so the vacuum canister is positioned in the correct way for easy adjustability of the timing.

 

[Bewy]

Dan,
I would not sweat that you didn't degree the cam. I have always found this amusing because you are only checking two lobes. What about the other fourteen?

Powell Machine had a recent video showing incorrect indexing of some lobes.

 

[Dan the man]

Because the cam gear turns at half engine speed, It doesn't matter if you choose 6 and 12, or 6 and 6 for to slide the gears on, prior to degreeing.
But before you drop the D in, just make sure you got the right cylinder at TDC compression. And it doesn't even matter which particular Cylinder is at TDC Compression, so long as you put the rotor under a tower, and call that tower by the same number as is the cylinder that is at TDC compression, then wire the cap accordingly. Oh and, the oil-pump drive has to be engaged.
There are only two reasons to do it per the book;
1) the factory precut Ignition wires are pretty short and some cylinders will not fit no matter how you juggle the wires around, and
2) is convention. Down the road if somebody takes the D out and isn't paying attention, then it is highly unlikely that he will get it back together right, cuz he's looking for the rotor to be under a certain tower with #1 at TDC compression.

I've always used the 6 and 12. I install the distributor with the rotor pointing to the number 1 terminal and I've never heard any issues with the engine starting or adjusting the ignition timing. Engines that I've done this way have all ran well and had good performance for what they were.

 

[Inertia]

As said, either is correct, in one position cyl#1 is firing, in the other position cyl#6 is firing. - both pistons are at TDC at the same time.

That's why you can set timing on an engine with either #1, or #6 plug wire.
( V-8 and most 6 cylinder engines )

Both will be correct . ( If crank is indexed correctly).

 

[toolmanmike]

I find it easier to install the chain at 6 and 12 because the marks are close together and it's easier to see if you are a tooth off. Then, just spin the crank over a full turn and line up #1.

 

[PRH]

It doesn't matter if you choose 6 and 12, or 6 and 6 for to slide the gears on, prior to degreeing.

6 and 6??

Good luck with that.

Bottom gear dot at 6 has the #1/#6 pistons at BDC.