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initial timing 25*.... Really? #75245
06/17/08 10:11 PM
06/17/08 10:11 PM
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Puyallup, WA
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StealthWedge67 Offline OP
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I've always timed my car by vacuum guage & ear. The mark was always off the tab so I didn't know exactly where it was, but I always figured around 18 - 20. Well, I used my friends dial-back timing light today, and it shows 24*-25*! Is this a little strange?, seems extreme to me(??) Here's the combo:

stock bottom 383; 9.25:1
Stock 516 heads
Edelbrock RPM intake
Holley 750 Vacuum Sec.
1-3/4" headers
Delta Custom Cam (.480 & 238 @ 050; .496 & 242 @ 050; 110* cl)
Rhodes lifters
Mallory Mag-breakerless distributor

Should this combo be using that much enitial timing? I'm only keying in 14* advance to get me to 38* total. (thats the smallest key that comes with the distributor!)


LemonWedge - Street heavy / Strip ready - 11.07 @ 120
Re: initial timing 25*.... Really? [Re: StealthWedge67] #75246
06/17/08 10:26 PM
06/17/08 10:26 PM
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Rancho Cordova, CA
Exit1965 Offline
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Im running about 22 on a 245 @ .050 cam with 108LC, using the same distributor (uses red keys to set advance anyways) with 14 mechanical. I first adjusted it by ear too but it didn't seem to gain any with 25 and i wanted to keep the total around 35-36. I tried 35 degrees at idle (using one very light spring in the dist) and it did not run very good like that, but I have heard of people with bigger cams (260 @.050) running that much or more at idle. im using one of the fast advance curve spring setup, all in by 2000 I think.

So 25 doesn't sound unreasonable..

Re: initial timing 25*.... Really? [Re: StealthWedge67] #75247
06/17/08 10:29 PM
06/17/08 10:29 PM

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You've just discovered why I ALWAYS like to scribe my balancer wheels, so I can SEE what the timing is doing.

By the way, unless you have a GOOD quality delay light, I just don't trust them. I've seen a number of inexpensive lights that were not accurate on delay.

If you KNOW what your dist. curve is, that's way too much advance. Timing is really quite simple. If you were to lock the distributor--no advance, the timing would be whatever initial is set at. You simply add the advance curve to the initial, and the vacuum, if used, and all of them are your possible total.

The other thing about using "plenty" of initial, is that yea, it makes the engine "sound" very crisp and responsive, but you can get into situations where the driveability at low/ med RPM's and under a hard pull, the thing may not make as much torque as it should, and you can even run into serious knock /ping issues.

I used to run about the same cure you have, IE 28* in the dist. I set the total--checked at high RPM at 38* or so, and that gave me an initial of 10 or so. Weak springs help it advance quickly.

Last edited by 440sixpack; 06/17/08 10:31 PM.
Re: initial timing 25*.... Really? [Re: StealthWedge67] #75248
06/18/08 01:54 AM
06/18/08 01:54 AM
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Aurora, Colorado
451Mopar Offline
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Sounds OK to me expecially with the big cam, and I doubt the engine is built for low rpm RV use.
By the time I hit the converters stall speed I'm at full advance reguardless of what the initial setting is

Re: initial timing 25*.... Really? [Re: 451Mopar] #75249
06/18/08 02:35 AM
06/18/08 02:35 AM
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Carstairs, Alberta, Canada
dave571 Offline
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9.25:1 with 238 @ 50 , will like around that much.

I have 10.7:1 with 242 @ 50 and run 24 intial. total is 35, so the mechanical advance is only 11 degrees.

Curved right, running a high intial number will only help performance and throttle response. It's all good, unless you bring it in too fast afterward, and/or have too much total.

So at 35, you need to shorten that curve down to 10 or so. If the distributor is untouched, it may have as much as 25 mechancal in it.

Re: initial timing 25*.... Really? [Re: StealthWedge67] #75250
06/18/08 06:36 AM
06/18/08 06:36 AM
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Indiana
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I run 24 initial with a much smaller cam of 226/238 @ .050" all in (34) by 2400rpms in my 9.7:1 340. This makes for a strong vacuum signal at idle and crisp throttle response. Like said before, you need to slow down the curve to keep it from pinging. The only ill-affect is that the starter may kick back but the mini starter takes care of that issue.
Note: I tested 18,20,22,24, and 26 initial before I decided to keep it at 24 just to get some back to back driving comparisons. Then once I had the initial where my combo liked it, I had FBO recurve the dizzy with the 24 degrees initial. Don had no problem with that timing on my setup.


1970 YO7 A66 [Canadian Export] F8 Challenger
340 (Currently in shop for stroker assy.)
Re: initial timing 25*.... Really? [Re: YO7_A66] #75251
06/18/08 07:43 AM
06/18/08 07:43 AM
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places
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79powerwagon Offline
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Hey Windows users, the "degree" symbol is:

(right hand) ALT plus (keypad only)0176, and you get a "°" symbol!

Just so you know...

Re: initial timing 25*.... Really? [Re: 79powerwagon] #75252
06/18/08 08:02 AM
06/18/08 08:02 AM
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Brookeville, Md
Mr.Yuck Offline
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Brookeville, Md
I never really worry about initail. Like you I tune the carb, vacuum as such then set total timing. I have found most 383's like some timing. 38* total and up. If it's running good leave it. If you want try backing it down and see how it runs what's the harm???

Re: initial timing 25*.... Really? [Re: Mr.Yuck] #75253
06/18/08 11:14 AM
06/18/08 11:14 AM
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Posts: 4,319
Puyallup, WA
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StealthWedge67 Offline OP
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StealthWedge67  Offline OP
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Thanks for the responses. Sounds like I'm about where I should be. I've left it at 24 enitial, and keyed in 14 advance, for 38* total (no vacuum, and lets not start that conversation). We'll see how it runs like this, & go from there.

Last edited by GEnsrud; 06/18/08 11:15 AM.

LemonWedge - Street heavy / Strip ready - 11.07 @ 120






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