Cam Timing Dots...how do I set the distributor now? - Team Camaro Tech
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post #1 of 12 (permalink) Old Sep 2nd, 04, 10:07 AM Thread Starter
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I installed my new camshaft and lifters and am getting close to ready to fire it up. I need to do a few things, like change the oil and add some EOS, etc.

I set the cam timing dots to be pointing towards each other. I had set the car to TDC for #1 before I disassembled anything. I proceeded to swap out the cam. I lined up the dot on the cam gear with the crank gear. Everything looks perfect, the keyway for the crank is at about 2 o'clock, so everything is correct according to my engine book.

My question is, what cylinder is on it's compression stroke, #1 or #6? I already installed my distributor and got it lined up with 10* static advance timing for #1. Should I be setting the dist to fire on #6 instead? Or should I rotate the crank 180* and set the Dist at #1 like I have it? Or am I already doing it correctly?

Thanks!
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post #2 of 12 (permalink) Old Sep 2nd, 04, 10:15 AM
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Josh, do you recall what cylinder position the dist rotor was pointing at when you pulled the dist out? If not, you'll have to determine if your crank is turned to the compression stroke of #1 or #6. Once you figure that out drop the dist to match up with the corresponding cylinder.

On the other hand if I'm not mistaken, then with the two marks lined up you should be at #1 firing so drop the dist accordingly and ballpark the timing and crank it over. Worst case is that your 180* out and just have to lift and turn the dist to the correct post.
I hate posts like this too. [img]graemlins/clonk.gif[/img]

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post #3 of 12 (permalink) Old Sep 2nd, 04, 10:44 AM
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With the dot on the crank gear at the top, and the dot on the cam gear on the bottom, you're at TDC firing #6.

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post #4 of 12 (permalink) Old Sep 2nd, 04, 10:57 AM Thread Starter
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So, I should either pull the dist and rotate the crank 360* back around to TDC and be at firing #1, or more easily, just pull out the dist, turn it so the rotor is pointing at #6 and drop it back in?

That sounds easy enough, since it should line up with my oil pump shaft if rotated 180*.

Another question, should the oil pump shaft be wobbly? I noticed that when I peered down the hole and took my long screwdriver to rotate it to point at #5 intake, it was able to wobble back and forth about a 1/8" or better. Is that normal?
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post #5 of 12 (permalink) Old Sep 2nd, 04, 11:11 AM
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It can be either 6or1 remember the cam turns at half the crank speed. Make sure the in and ex valves are at 0 lift for number one then you are at TDC for number one.
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post #6 of 12 (permalink) Old Sep 2nd, 04, 12:29 PM
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If the dots on the timing gears are pointed towards each other it's definitely TDC#6. Just rotate the engine 360 degrees so both dots point straight up and you'll be at TDC#1.

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post #7 of 12 (permalink) Old Sep 2nd, 04, 02:03 PM
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Josh, I suppose it depends on which connecting rod you have for the pump, I bought one of the newer type that doesnt have the tension screw on it so mine tends to wobble as well. Either way wont matter once the distributor is bolted down. It will be sandwiched between the two with no chance of popping out.

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post #8 of 12 (permalink) Old Sep 3rd, 04, 12:08 AM
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with the dots lined up pointing towards each other, that's #6 firing. that never made sense to me, but that's how it is.
as for the oil pump shaft, it is located inside the distributor gear and won't move around at all once the dist is jammed in.

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post #9 of 12 (permalink) Old Sep 3rd, 04, 07:20 AM
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Been a long week, You could turn the cam gear 3 million degs and it would still have the alignment mark in the same place in relation to the cam. Unless I am completely nuts I have had cams that were setup with number one on the firing position when the marks lined up. It makes no difference just as long as you get the dist. in correct.
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post #10 of 12 (permalink) Old Sep 3rd, 04, 08:33 AM
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You eventually recognize when the distributor is 180 out. A couple of loud bangs and a fireball out of the carb are tell-tale signs. When that happens, you lift the distributor up about an inch or two, flip the rotor around 180 and drop it back in. On GM engines, the oil pump shaft will not allow the distributor to drop in until it is ligned up. So it is a very simple procedure that takes all of 5 minutes to complete. Next crank it fires up and runs.

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post #11 of 12 (permalink) Old Sep 3rd, 04, 08:51 AM
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With the cam gear dot at the bottom and the crank gear dot at the top, it is indeed #6 firing. Some of the older manuals (like my old haynes manuals) show that the proceedure to install the cam is with BOTH dots at the top. I never realized why until figuring out that with both dots at the top, you are on the #1 cylinder firing.
Anyway, at this point you have 2 options. Either rotate the crank 180 and install the distributor for #1 firing, or just install the distributor for #6 firing. What I do is install them with the dots closest to each other, then rotate the engine over while watching the rockers. Rotate the engine 180* after the intake valve for #1 has opened and closed (at this point the timing marks and pointer will be correct if you have already verified tdc before getting this far), and you will be at tdc on the firing stroke. I have been doing all my engines this way for years and they all fire up nearly instantly. This way there is no question about being 180* out or not.
Trust me, after trying to fire one 180* out with open headers in a 30x40 metal building, you'll want to make sure the timing is set right

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post #12 of 12 (permalink) Old Sep 4th, 04, 01:40 PM
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This is not rocket science - when the crank and cam sprocket are "dot-to-dot" (crank dot at 12 o'clock, cam dot at 6 o'clock, both aligned) you're at #6 TDC; turn the crank 360* and both the crank and cam dots will be at 12 o'clock, and you're at #1 TDC. Period. Always. This is a fixed relationship. You can install the distributor either way, as long as the rotor is pointing at the correct wire tower. Makes no difference whether you use the "dot-to-dot" (12 and 6) method or the 12 and 12 method, as long as the dots are aligned to a vertical line between the crank and cam centerline; just install the distributor with the rotor pointing at the proper wire tower. [img]graemlins/thumbsup.gif[/img]

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