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Old 03-01-2011, 09:03 PM
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Edlebrock Carb Tunning

IM RUNNING A EDLEBROCK 1405 CARB ON TOP OF MY 350 CHEVY . Im have problems when i rev it to the redline in park or neutral it will rev great put when it comes down it stalls out and hard to restart can anyone help me out please thanks for you time
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Old 03-01-2011, 09:33 PM
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Quote:
Originally Posted by chevyman559
...when i rev it to the redline in park or neutral it will rev great put when it comes down it stalls out and hard to restart...
Why are you doing this in the first place?
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Old 03-01-2011, 10:08 PM
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doing what i was check spudder and it was not reving at all now it does then dies in not actully hit redline but revving it up off idle

Last edited by chevyman559; 03-01-2011 at 10:13 PM.
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Old 03-01-2011, 10:20 PM
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There might be a vacuum leak, the choke might be partially closed, the float level could be too low or too high, the power valve could be bad or wrong for the engine, idle mixture adjusted wrong, timing could be the problem, etc.

What other symptoms does it have- like how does it drive, what do the plugs look like, what's the total and initial timing, are you using a vacuum advance, what are the cam specs and compression ratio, what is the carb jetted, especially if different from stock?

Does the engine use any oil, what is the mileage on the engine since it was rebuilt, single or dual plane intake, what's the vacuum and compression test readings?
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Old 03-01-2011, 10:30 PM
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it uses no oil it idle fine when gear so there is no vacuum leak it run a lunati cam specs are 284/284 adv dur 218/218 dur@.050 .458/.458 lift lope sep is 110/106 im leaning to the mixture screws cause it didnt idle well but didnt die when on the throttle now idles fine
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Old 03-01-2011, 11:07 PM
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With that cam you can use a modified ignition advance curve. This can help the engine a lot. Depending on what heads you have, the total timing will be from 32-38. You want the total advance in as early as possible, usually this will be around 2500-3000 RPM.

You will want to use about 12-14 of initial timing(possibly more). To get these figures, you may need to limit the total advance that the mechanical advance supplies. The image below shows the slots and pins that limit the total advance available to the HEI distributor. The slots can be brazed up to limit the travel, or if you have a selection of weights and cams for the HEI mechanical advance, you may be able to find a combination that gives you what you need for total advance.



You will also want 10-12 of additional timing coming from the vacuum advance. This may require a vacuum advance limiter plate like the Crane #99619-1, #99619 Instructions, or you can make one. An AR12 vacuum advance can or one of the adjustable cans from the Crane or ACCEL would be a good unit if a new one was needed.

DETERMINING TDC will allow you to be sure the timing tab and damper are correct for TDC.

MAKE A TIMING TAPE to see/adjust the total timing, w/o needing to use a dial back timing light.

Good info on ignition timing (post 9)- Port or Full time vacuum
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Old 03-02-2011, 10:17 PM
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it sounds great but im confussed with all this i know i have new weights and springs and were do i start and how
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Old 03-03-2011, 04:01 AM
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Quote:
Originally Posted by chevyman559
it sounds great but im confussed with all this i know i have new weights and springs and were do i start and how
If you bought an advance weight and spring kit, start off by using the original weights and the pair of medium springs or one light and one medium spring.

Then see what RPM the advance tops out at, as well as how many degrees total there are. This will be done w/the vacuum advance disconnected and the line running to the carb that supplies the vacuum plugged off for now. When the mechanical timing has been set, you will reconnect the line.

You want the total advance to be about 36 degrees if the heads aren't Vortec or fast burn chambers, 32 degrees if they are. And you want all the advance to be there by about 2500 to 3000 RPM.

Finally, see what the advance drops to when the engine is allowed to idle. This will determine what more needs to be done, if anything.

Reconnect the vacuum advance and note how much advance it provides. In most cases about 10-15 degrees max is about right for the vacuum advance. If it gives you more than that, you can use a limiter plate sold by Crane to limit it, if you have an HEI distributor like many guys use.

You can do a search for terms like "set up advance curve" or "ignition advance HEI", etc. for more on the subject.
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Old 03-03-2011, 02:46 PM
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Hi,
In addition to the excellent advice on engine timing,

Check the fuel pressure to the carb. Based on my experience with my 75 BBC in my 75 GMC, the 1400 series prefers fuel pressure in the 4-5 PSI range. Anymore and you will have the issues you describe since it will essentially "flood out". Especially on California gas on hot days.

I resolved the issue with a Holley fuel pressure regulator and an Edelbrock phenolic spacer.

Good luck,

Matt
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