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Old 07-24-2011, 06:34 PM
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400 sbc timing issue

im having trouble understanding this whole timing thing any help would be appreciated
i have a 406 sbc with a lunati 60105 hydraulic tappet cam with 546 lift aluminum heads 10 to 1 comp. quick fuel 750 q series carb 350 turbo with 3200 stall when motor was installed i put the slot on my balancer a 12* btdc then put distributor in the engine. which is a brand new accel already set up with a good coil and curve kit installed fully adj. vac advance. motor starts fine runs awsome
my question is do i take a timing light now and set my balancer slot to zero on my timing tab? i'm lost from here and i want to fig. this timing out

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Old 07-24-2011, 07:36 PM
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If nothing else, at least throw a timing light on it to see exactly where it is now for future reference. I would look into trying for more advance like 14-16* initial with your cam. Turning it back to 0* would kill your power and torque across the board.
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Old 07-26-2011, 02:37 PM
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you should had put a mark on the balancer at TDC (0 degrees), then use a timing light with a dial to set the timing.

locked out timing with a start retard would be a good solution.

otherwise, set the timing at 25 at idle, and 36 total. should start ok warm with 25 degrees and a big cam.

is your distributor adjustable?
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Old 07-26-2011, 03:59 PM
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yes my distributor has an adjustable vaccum adv.
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Old 07-26-2011, 04:18 PM
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You need an adjustable mechanical advance slot.
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Old 07-26-2011, 04:31 PM
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whats a adjustable mechanical advance slot?
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Old 07-26-2011, 05:59 PM
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It allows you to set the amount the distributor advances.

so if you set the timing at 25 at idle, then you could reduce the amount of mechanical advance to only add 11 more to limit the total to 36 degrees (25 + 11 = 36). The stock advance is typically 20 degrees.

less advance is important with a big cam because it allows more initial advance without advancing too far, which is required for a big cam.

When you use a non-stock cam, it is important to use a non-stock timing curve.
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Old 07-26-2011, 08:20 PM
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i found tdc and my timing tab is correct i had 12 intial then i set it to 24* running at idle made marks on my balancer with precise measurements with a plastic tape i made a mark for a total of 36*. after i set my idle at 24 i then reved the engine to 3000 and it was all in by 2500 rpm. is this ok ?
my carb was really rich once i got my timing set




































8
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Old 07-27-2011, 07:43 AM
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makes sense, as more timing can run a leaner mixture. turn the idle speed and idle mixture down. That cams needs to idle at 1000 rpm.

so you are saying 24 initial and 36 total at 3000 rpm?

try revving it up to 4000 or 5000 rpm. I would guess the timing will go over 40. (not good)
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Old 07-27-2011, 05:16 PM
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I tried revving the engine further and the mark I made for 36deg didn't keep going it stayed where it should
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Old 07-28-2011, 09:00 AM
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that is good!

so how is is running now?
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Old 07-28-2011, 05:58 PM
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it will blow the tires off at 30 mile n hour it runs really well i just need to fine tune my carb n i think i will have thanks for all the help
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Old 07-28-2011, 06:26 PM
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Quote:
Originally Posted by 81malibuman
it will blow the tires off at 30 mile n hour it runs really well i just need to fine tune my carb n i think i will have thanks for all the help
That's fun isn't it
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Old 07-28-2011, 06:30 PM
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Originally Posted by HalfOunce
That's fun isn't it
Yeah, if I drove today like I did when I was 21 I'd have to take out a loan for new one's every 3 mo.
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Old 07-28-2011, 09:15 PM
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drove car to town tonight to a cruise in at my local advance auto and car seems to be running good no pinging or nothing major. carb has a little miss in it at @ 2000 and my idle needs a little more tuning im gonna take carb off tomorrow and check my throttle plates then set my mixture screwa with a gauge for best vac. at idle
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