Carb or Timing
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Carb or Timing
1979 F-250, Auto, 400, Holly 600 cfm
New Parts
1. Fuel Pump
2. Fuel Filter
3. Coil
4. Ignition Module
5. Plugs, wires, dist cap and button
I had an edelbrock on it and it never run right. Whenever I would get it running properly, if it sat for a week or so it would spit and sputter and foul the plugs. This was even after I ran non-ethonal gas. I got a holly 600 and it's much better. I've got the timing set about 10 btc. I've also made sure that every cylinder is timed properly. It runs great under moderate load and at idle. Under heavy acceleration it will skip and I have to back out of it. Does this sound like a carb adjustment problem or should I try advancing the timing more? I have set the float on the primary but not the secondary, could that be it? Any help please, I'm pulling my hair out.
New Parts
1. Fuel Pump
2. Fuel Filter
3. Coil
4. Ignition Module
5. Plugs, wires, dist cap and button
I had an edelbrock on it and it never run right. Whenever I would get it running properly, if it sat for a week or so it would spit and sputter and foul the plugs. This was even after I ran non-ethonal gas. I got a holly 600 and it's much better. I've got the timing set about 10 btc. I've also made sure that every cylinder is timed properly. It runs great under moderate load and at idle. Under heavy acceleration it will skip and I have to back out of it. Does this sound like a carb adjustment problem or should I try advancing the timing more? I have set the float on the primary but not the secondary, could that be it? Any help please, I'm pulling my hair out.
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The edelbrock, I've researched and used all the charts to change metering rods and jets to try and compensate for the problems I was getting. Still always some issue. Thats why I'm thinking maybe timing. The holley came from a friend. The only thing i've changed on it is the primary float adjust and the idle mixture. Where do I need to start?
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The Edelbrock wants lower fuel pressure. 4'ish PSI vs 7-9 for the OE fuel pump and Holly. An Edelbrock carb needs a regulator. Holly regulators seem best. That may have been the problem with the Edelbrock.
With the Holly, when it stumbles and you back off, can you get back on it and make it go? In other words, if you nurse it can you get it to run right at WOT?
With the Holly, when it stumbles and you back off, can you get back on it and make it go? In other words, if you nurse it can you get it to run right at WOT?
Post Fiend
Joined: Mar 2011
Posts: 8,501
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From: Lynchburg, VA
So basically, you aren't properly setting up your carbs.
The Holley may still require a fuel pressure regulator, but it may not. If you haven't already, get you a set of jets, accelerator pump cams, and secondary springs. If you don't already know what a plug chop is, familiarize yourself with the procedure. Get the float heights set, then get the right jets in there. If you've still got stumbling during throttle movement, swap out pump cams till it feels right.
If you have a ton of trouble with setting the float heights, and the fuel levels seem to jump around (random flooding/starving), get a fuel pressure regulator on there and dial the pressure down.
The Holley may still require a fuel pressure regulator, but it may not. If you haven't already, get you a set of jets, accelerator pump cams, and secondary springs. If you don't already know what a plug chop is, familiarize yourself with the procedure. Get the float heights set, then get the right jets in there. If you've still got stumbling during throttle movement, swap out pump cams till it feels right.
If you have a ton of trouble with setting the float heights, and the fuel levels seem to jump around (random flooding/starving), get a fuel pressure regulator on there and dial the pressure down.
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Postmaster
Joined: Nov 2011
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The Edelbrock wants lower fuel pressure. 4'ish PSI vs 7-9 for the OE fuel pump and Holly. An Edelbrock carb needs a regulator. Holly regulators seem best. That may have been the problem with the Edelbrock.
With the Holly, when it stumbles and you back off, can you get back on it and make it go? In other words, if you nurse it can you get it to run right at WOT?
With the Holly, when it stumbles and you back off, can you get back on it and make it go? In other words, if you nurse it can you get it to run right at WOT?
FWIW factory specs for initial timing on 400's varied depending on emission setting from 8-12 degrees from memory. Mine is set at 12. A couple more degrees of timing may work well but not your main problem.
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