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1974 620 timing degrees


Richie

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17 minutes ago, Stoffregen Motorsports said:

You don't actually need a vacuum advance. If you disconnect it, you can add in a couple more degrees of base timing and get a better throttle response. Ideally, the timing on a small motor like an L18 would be about 12-15 at idle and then top out at about 32 degrees at around 3000 rpms.

yep

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So I take it the vacuum advance is not working???

 

What about the timing not advancing when revved up. This would be the mechanical or centrifugal advance. It's not working either???? Both not working???

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1 hour ago, datzenmike said:

So I take it the vacuum advance is not working???

 

What about the timing not advancing when revved up. This would be the mechanical or centrifugal advance. It's not working either???? Both not working???

So the rod in the video is moving, and the vacuum is hold pressure. It is just not moving the whole unit as if it is advancing. Yes when i rev the engine the timing does not advance. 

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The breaker plate may be seized and why the rod tries to move but can't. Grab the plate the points are on and try turning it. It may let go.

 

Same with the rotor. Grasp the rotor and turn to try and loosen it.

 

 

Next is take it apart and loosen everything and grease it. Running without either is not good for performance or mileage.

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Pay attention to the clocking of the distributor cam when you remove it. If you put it on backwards, your timing will be 180 degrees out.

 

Also, pay attention to the spring tension on the weights. If there is no tension or the springs are loose, this could cause your timing to come in right away, which is why you're not seeing it move. Likewise if the springs are too tight. Ideally, the springs would be just touching the weights and the tabs holding them on the other end. If they are loose, you can bend the tabs with a pliers.

 

This isn't hard, but should be done by someone who knows what they are looking at.

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57 minutes ago, Stoffregen Motorsports said:

Pay attention to the clocking of the distributor cam when you remove it. If you put it on backwards, your timing will be 180 degrees out.

 

Also, pay attention to the spring tension on the weights. If there is no tension or the springs are loose, this could cause your timing to come in right away, which is why you're not seeing it move. Likewise if the springs are too tight. Ideally, the springs would be just touching the weights and the tabs holding them on the other end. If they are loose, you can bend the tabs with a pliers.

 

This isn't hard, but should be done by someone who knows what they are looking at.

https://imgur.com/eoUP97K

 

https://imgur.com/eoUP97K

 

https://imgur.com/zQbxuo9

 

https://imgur.com/5JS71RI

 

So i think I fixed it. does this look correct? The hand pump was holding pressure because it was hard to seal the hose on the vacuum. I used my mouth in one of the videos. 

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Good, so you have determined that the vacuum advance is working.

 

Now, grab hold of the metal portion that the rotor slides onto (this is the distributor cam) and hold the base of the distributor shaft, at the bottom where it stabs into the drive spindle.

 

While holding firm the base of the distributor shaft, can you rotate the distributor cam at all? If so, how much tension is there? I mean, how hard do you have to work to twist it? A lot? A little? Does it move at all? This is what's known as mechanical advance.

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22 minutes ago, Stoffregen Motorsports said:

Good, so you have determined that the vacuum advance is working.

 

Now, grab hold of the metal portion that the rotor slides onto (this is the distributor cam) and hold the base of the distributor shaft, at the bottom where it stabs into the drive spindle.

 

While holding firm the base of the distributor shaft, can you rotate the distributor cam at all? If so, how much tension is there? I mean, how hard do you have to work to twist it? A lot? A little? Does it move at all? This is what's known as mechanical advance.

It moves a little, some tension is on it like there are springs holding back almost. I can also hear it when i move it. Does take some strength but not to much. It doesnt move a lot just a little bit

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so i hate to admit this but, when i was putting in the electronic pickup I must have not attached that black screw back onto the vacuum advance correctly. because when i took it apart I noticed the shaft wasnt screwed into the plate to move it....

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2 hours ago, Richie said:

It moves a little, some tension is on it like there are springs holding back almost. I can also hear it when i move it. Does take some strength but not to much. It doesnt move a lot just a little bit

 

Does it spring back?

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5 minutes ago, banzai510(hainz) said:

Personally I dont think the dist is bad.

a video of the motor running with the timing light  on the crank would have helped better to see whats it doing. at idle and rev up and adjusting the dist adv and retard

I did post one on this thread

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23 hours ago, datzenmike said:

 

The distributor wasn't advancing  at all when revved up. It was shown that the vacuum advance was also stuck or inoperative. Work has been done on both these problems so time for an up date.

 

Is this advancing to 32 degrees above 3k????????

Does the advance jump up when held at fast idle and suddenly let off???????

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6 hours ago, datzenmike said:

 

The distributor wasn't advancing  at all when revved up. It was shown that the vacuum advance was also stuck or inoperative. Work has been done on both these problems so time for an up date.

 

Is this advancing to 32 degrees above 3k????????

Does the advance jump up when held at fast idle and suddenly let off???????

So i hooked up the dizzy today, and reved it up and it sounds so much better now. I didnt have a timing light to see the degrees but before I broke down the dizzy, I could only rev it up 3k rpm until the the carb started back firing. Now it hold and no back firing.

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