back fire underhard acceleration - Team Camaro Tech
Troubleshooting Diagnosing problems done here.

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post #1 of 3 (permalink) Old Mar 28th, 04, 01:47 PM Thread Starter
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i just finished my restoration and a 69, put a 383 in it. I am using a Barry Grant speed demon 750. When I nail it it bogs, but recovers quickly.

69 x-11..LS1, 420.88 horse to the tires,750 Holley Ultra DP, Torquer V2, darksides headers, PRC heads, 10.8:1 compression, forged bottom end, 5 speed. 2008 King Ranch F150 4x4.
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post #2 of 3 (permalink) Old Mar 29th, 04, 05:41 AM
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Welcome to the Club! Bogs, but recovers. I will givew three suggestions:
1. More initial/total timing
2. If bogs right after WOT, then squirter size too small. Work up in .003" sizes until bog/stumble disappears.
3. Engine runs good from WOT, but, falls, lasts for about a half second, then dies. Could be running out of fuel volume from accelerator pump. Either move pump cam to another position or install cam increasing amount of volume.

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post #3 of 3 (permalink) Old Mar 30th, 04, 12:42 PM
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Just like Everett said . . .

The first thing to do though is to decide whether its a rich bog (puffs black smoke out the back) or a lean stumble (pops back through the carb).

Then you need to determine if it is happenening immediately when you nail the gas or a split second after you hit the gas.

If a lean stumble happens right away, you aren't getting enough fuel in there quick enough. Try a larger pump squirter and a larger pump cam.

If it goes for a split second then lean stumbles then goes again, the pump shot isn't lasting long enough to cover the transition. Try a smaller squirter.

If its a rich bog, then try smaller squirters and smaller pump cams.

Pump cams control how MUCH fuel is squirted each time the accelerator pump is pushed.

Pump squirters determine how LONG that pump shot lasts.

Hope this helps.

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68 Camaro, E85 powered 427" small block. 9.96 @ 133 MPH, 1.319 sixty foot on motor. 5.92 eighth @ 116 with a 1.42 sixty breaking beams with back tire on the bottle
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