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Old 08-05-2010, 11:09 AM
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new holley 650 backfires

I have a new holley 650 db pump/manual choke on new hi-rise manifold. built sbc in streetrod, engine starts ok but bogs down a little when i first hit the accelerator then when i shut the engine off it pops through the mufflers.

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Old 08-05-2010, 01:17 PM
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Check your timing.

Is the carb adjusted or just dropped in? Idle mixture, float levels, idle speed?
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Old 08-05-2010, 02:11 PM
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Set the ignition timing accurately with a timing light.

If this motor has a big racey Rough idle cam in it, it will need specific non stock setup on the ignition timing curve.
In this case a "stock" or "out of the box" new distributor will need some setup changes.

A carb motor has to "warm up". Let the thing warm up completely before you evaluate the throttle response.
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Old 08-12-2010, 07:29 AM
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carb issue

this is a 350 sbc bored to 360 fuelie iron heads, 202,160 ported, block was blue printed, 450 lift cam, it's either 10.5 or 11 to 1/ compression I can't remember. I set the floats, used vacumm gauge to set idle mixture. I was told not to use the vacumm advance on the distributor so it is blocked off, due to the high compression.? New HEI GM distributor , this motor has less than 10 hrs on it. not sure if this is the way to go. thanks
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Old 08-12-2010, 10:25 AM
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what cam is in this motor? The vacuum advance will need to be modified to work right with this modified motor. The mechanical advance will need to be modified also.

What is the cam in this motor?
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Old 08-18-2010, 06:16 PM
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carb

I think the it was a competition cam with a 455 lift, I can't remember excatly . it was 10 years ago that I had the engine built.
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Old 08-19-2010, 02:39 PM
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dist adjustments

how hard is it to modify the distributor? It's a new HEI gm. Ir is there a better aftermarket dist that i could that doesn't need any modifications? If there is would it be alright to then use the vacumm advance and what would i set the timing at. thanks pc
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Old 08-19-2010, 05:08 PM
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How much effort are you willing to put into tuning your own motor?

Starting with determinimg what cam is in the motor.

Search my old posts using relevant keywords on modifying HEI distributors
for high perf applications.
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Old 08-20-2010, 02:21 PM
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If I don't have to take the motor apart I don't mind doing the work.
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