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Old 08-12-2004, 10:09 PM
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High initial timing ?

What do you thing about an initial timing of 20 degrees ? The 350 on my 72 SS El Camino likes it there! It has a mild cam, an air gap manifold, a 670 holley and a Mallory 9000 series breaker-less distributor. I came to this setting while trying to get rid of a slight hesitation under normal (and hard) acceleration ......say at a stop light. No matter where I jetted it or how I changed the accelerator pump discharge nozzle it would still have this hesitation. But I noticed that as I set the timing higher it would lessen. So I slowly work up to 20 and now the hesitation is gone! There is no engine ping or hard starting like I have on other engines. The only other thought I had was to re-curve the distributor. But this is working and I wanted some input from the forum before I try any thing else........what do you think?

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Old 08-12-2004, 11:29 PM
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if it's got a bigger than stock cam in it, it needs higher initial time than 12-14 deg. i run my timing on 22-24 deg at idle, with it maxing out at 36-38 deg @ 2600 rpm. the only motor i have done that i can't run that much initial timing is the 406 thats in the car now. it has to much compression for it. it starts fine (even when hot), but want's to run on after it's been turned off. they run better on the bottom end, & have less stumble with the higher initial timing. i also unhook the vacuum advance in the distributor to be able to get the timing curve just right.
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Old 08-13-2004, 10:38 AM
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I am glad to hear that someone else has had this experience with another engine........I don't have a vac advance on this distributor ....would I have to run the timing as high if I recurved the advance?...............anyone?
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Old 08-13-2004, 10:51 AM
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when you recurve the distributor try to get the initial timing @ 22-24 deg & the total time @ 36-40 deg, just depends on how much it needs.
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Old 08-13-2004, 10:58 AM
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Thanks........I'll "get er done"
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Old 08-13-2004, 10:59 AM
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I have had the same experience with a 70 350 with 10.25 compression and a longer duration camshaft. The balancer outer hub can be spun out of proper alignment to TDC, as it is only held by rubber. So long as it starts good without seeming too cranky (especially after runnning for a while) and does not ping it should be fine. My timing mark is almost at 12 oclock when it runs the best!
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Old 08-13-2004, 11:30 AM
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My harmonic balancer also had spun.........I replaced it with a new after market balancer........this hesitation had been on going for about 4 months until I ran the advance up to 20.

He;y 406 SS.......
Why do you think I need to move the advance up to 22-24?
What decides what your engine wants?

whoops.........

Hey 406 SS.......
Why do you think I need to move the advance up to 22-24?
What decides what your engine wants?

Last edited by stinky jinx; 08-13-2004 at 11:29 AM.
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Old 08-13-2004, 11:37 AM
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usually the base setting is 12 degree`s before TDC, then with the vacuum advance connected to a manifold source it`ll be in the 24 degree range, if your not running a vacuum advance you`ll have to give it more intial advance to compensate for it.
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Old 08-13-2004, 01:35 PM
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enough with the manifold vacuum on the vac advance already! does not work worth a $%&*!
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Old 08-13-2004, 01:45 PM
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Quote:
Originally posted by ratlover
enough with the manifold vacuum on the vac advance already! does not work worth a $%&*!
Wrong!!!
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Old 08-13-2004, 01:55 PM
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TIMING

Jinx, you should be ok with that set up. I would not worry about the vacuum advance being hooked up. I would do one thing. Put a brand new set of plugs in it. Take it for drive the way you would normally drive, maybe spank it if you like... Then pull the plugs and look for signs of detonation. If the plugs look fine then you are set. You are not going th HEAR detonation in a motor like your with your ear....

Keith
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Old 08-13-2004, 02:15 PM
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whatever...
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Old 08-13-2004, 10:01 PM
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K-Star....(or any one who cares to answer)

I know what I am looking for on the plug when I am setting the jets ..........but what am I looking for when I am looking for detonation?
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Old 08-13-2004, 10:24 PM
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i've seen it in several books about setting the timing up the way i said. vacuum advance's are junk! it's easier to get the advance curve right with it unhooked. people will argue with me on this, but i know i'm right. if you have a larger than stock cam, you need more initial timing. 20-24 is plenty, just make sure your not getting any detonation (little melted balls on the plugs). think of it like this, the longer duration cams bleed off cylinder pressure, so to help make up the difference i turn up the initial timing. this helps get rid of the hesitating, & sluggish bottom end, caused buy the wider valve overlap, & duration.

every time i would try to get the timing set with a vacuum advance hooked up, the total timing would be up over 60 deg. i even tried a adjustable vacuum advance. their friggen junk too.

ratlover, i agree, a vacuum advance is junk. the only good thing about them is it gives me some thing to grab so i can turn the distributor easier (lol).
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Old 08-14-2004, 06:27 AM
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plugs

Look for black specks on the porcelin. Also look for welding typ spatter anywhere on the metal parts of the plug.

The ground strap of the plug should be discolored back to the bend. If the heat mark on the ground strap goes the whole way where it's attached the plug is to hot, you will need to go down a heat range or 2

Keith
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