initial timing 25*.... Really?
#75245
06/17/08 10:11 PM
06/17/08 10:11 PM
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Posts: 4,319 Puyallup, WA
StealthWedge67
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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
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Re: initial timing 25*.... Really?
[Re: StealthWedge67]
#75247
06/17/08 10:29 PM
06/17/08 10:29 PM
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Anonymous
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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.
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Re: initial timing 25*.... Really?
[Re: 451Mopar]
#75249
06/18/08 02:35 AM
06/18/08 02:35 AM
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Joined: Dec 2003
Posts: 5,314 Carstairs, Alberta, Canada
dave571
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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.
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Re: initial timing 25*.... Really?
[Re: StealthWedge67]
#75250
06/18/08 06:36 AM
06/18/08 06:36 AM
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YO7_A66
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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.)
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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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79powerwagon
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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...
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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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Joined: Jul 2006
Posts: 4,319 Puyallup, WA
StealthWedge67
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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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