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Discussion Starter · #1 ·
Hey guys,
Wait!! before you hit that back button, please dont be intimidated by the long post. I am just a little long-winded. Look at this picture!!
http://www.geocities.com/w_surfer99/EngineDiagram.html

For those who don't know, My Velle has a 307ci (bone stock) with the upgraded HEI ignition (coil in cap). Bare with me cuz I am a moron when it comes to specifics like setting timing or even knowing anything about ignitions. But I went out today and check my initial timing which seemed to be at 8. Typical right? And since I don't have a vaccum pump to check my vaccum advance, just checked my centrifugal advance. My timing light has the advance nob on the back. So here's what I did:

I checked my initial timing with everything hooked up and it came out to 8. Then I slowly turned the advance nob until the timing notch on the balancer moved down to 0. So the gun said 11. Shouldn't the gun's advance match the initial timing? Next:

I checked centrifugal advance, but since I dont have a tach, I just figured that at about between 1/3 and 1/2 throttle was about 2500rpm. This was with the vaccum advance plugged. Tell me if I am wrong. I just kinda played it by ear. And so with the advance nob on the gun at 0, the notch on the timing tab said about 12 or 13. To get the notch back to 8 it took about 12 on the gun. Now added to the initial doesnt that give me about 24 total advance. Is that right?

Well I didnt know so I tested it with the vaccum advance hooked up. with throttle at between 1/3 and 1/2 the notch jumped up to 16. To get it back down to 8 it took about 17-18 on the timing gun. Thats makes the total advance with the vaccum about 29. Is this right?

I noticed however that when I slowly progressively gave the car more juice from idle, that before the notch would move upwards on the tab, It moved down first, a short distance. And very slowly (without the vaccum hooked up) Made its way up. But it seemed to stay still after dropping down, for a bit. The notch did the same thing with the vaccum hooked up. It dropped down first, but of course moved more quickly up the timing tab. Does thi sound right. This is my first time doing this.

Take a look at the diagram in the link. I altered the image so that you can see exactly how my distributor is sitting. Does it look right? Is it normal for the distributor to be rotated 180 degrees from TDC like that?? Here it is again:
http://www.geocities.com/w_surfer99/EngineDiagram.html

Let me know what you guys think.

Thanks

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69 Post

JOHN
1969 Chevelle
http://www.geocities.com/w_surfer99/index.html
 

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Discussion Starter · #2 ·
Oh yeah, and one more thing. The car was running perfect at this setting. Great response and great performance especially for a 307.

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69 Post

JOHN
1969 Chevelle
http://www.geocities.com/w_surfer99/index.html
 

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Distributor was dropped in on exhaust stroke, and person didn't feel like taking it out, so they compensated for it by just moving wires. It's easier just to yank the distrib. than to re-arrange the wires...
 

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I am no expert, but I have been reading and messing with my distributor a lot lately, so I know a little.

check your initial at idle with vacuum line disconnected and hose to carb plugged.

For total, keep increasing the throttle until it quits advancing (with vacuum still disconnected). Just keep the light pointed at the balancer while increasing the throttle and watch for for the mark to stop moving. you might have to move the advance knob to keep the mark in view. What you read when it stops advancing is the total, you don't have to add this value to the initial to get the total. The initial number you found first is subtracted from this value to find your mechanical advance.

You find your vacuum advance by rechecking the timing with the vacuum hooked back up to the canister and subtracting the value found from what it was before hooking up the vacuum. You can do this at idle (if your vacuum line is hooked up to "manifold" and not "ported" (ported vacuum goes away at idle, so you will get no vacuum advance). It is hard to do this without a tach, since your idle speed will change sometimes with the vacuum hooked up (due to the added advance).

You can get a multimeter that has a tachs on it to check your RPM. This is useful to check your idle speed (should be around 850), as well as making sure your advance comes in early enough (all done by 2500 to 3000 RPM).

As far as your timing light not agreeing with your pointer, maybe you are misreading the pointer. You can also borrow another timing light and compare the readings. Your procedure sounds right, though.

you might want to experiment with your advance, you might find even more power that is unused. my 2bbl 283 likes 17° initial, 35° total, with another 15° vacuum on top of these.


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Charles Perrell
[email protected]
65 malibu SS Convertible
283 2v powerglide
 

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John,
The motor could not care less as to where the distributor sits, as long as each cylinder fires when it is supposed to. What about the newer cars that have no distributor ??
Now to your problem, it sounds like the advance mechanism on your HEI is just plain worn out, or has the usual HEI "rust and crust" syndrom. Remove the cap and rotor and inspect the advance weights and shaft. It should move very freely and the springs should not be flopping around loose. This causes the advance to do crazy things.
Hope this helps,

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Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100
 

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BillK is right. I used an HEI from a junkyard and the car ran okay, but seemed to be 'off' a little. I was playing with timing and with the cap off, I could move the rotor around and advance it by hand and it would stay were I left. i.e. it did not spring back to the orginal position. Pulled the whole thing and disassembled the shaft and the grease had solified into a thick brown mess. Cleaned it up and used some high temp disc brake grease. No problems since. Also check the bushings on the weights, my were worn through one side of the bushing. Good luck. -John

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64 Malibu SS 327
Parting out 1965 El Camino
Instructions?...all I need is the exploded view
 

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