Thread: Edelbrock carb problems

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Hiya, I know from bitter experience the 750 is way too big for a small block 350. 600 is as high as it goes unless you got a blower. Put the 750 on a big block. It's sucking way too much air.

In my opinion, the 750 Edelbrock is a bit much for a stock 350, however; it can be made to perform very well. They do tend to run rich out of the box and more often than not, I’ve re-jetted and installed new metering rods to prevent them from single handedly supporting OPEC. Definitely download the installation/tuning guide from Edelbrock: http://www.edelbrock.com/automotive_...411_manual.pdf



I have the following questions:
1. Have you run this combination successfully before?
2. What modifications have been done to the engine?
3. You said it was just “rebuilt” – did this entail new jets and metering rods? (See my recommendations below).
4. What is you manifold vacuum?
5. Are you running a stock distributor? If so, is it HEI?
6. Which port do you have the vacuum advance connected to (assuming it’s a stock distributor of one requiring vacuum advance).

Like all carburetors, the Edelbrock performs best when the air to fuel ratio is 14.6:1.

All Edelbrock carburetors have three systems that meter fuel to the engine: Idle, Primary, and Secondary.

Idle delivers 100% of the idle fuel. It also meters fuel at off-idle throttle positions.

Primary (main) - delivers an increasing percentage of fuel as throttle position passes through idle and varies fuel delivery in response to air flow and manifold vacuum.

Secondary: The Secondary only delivers fuel when the secondary throttle plates and air valve are open. It ensures that fuel delivery varies with air flow. The secondary plates should start to open when the Primaries are about 65% open. The Primary and Secondary plates must arrive at the wide open throttle (WOT) stop at the same time.

Fuel pressure is critical for Edelbrock carbs as well. At idle, you should not have more than 6.0 psi. I set adjustable fuel-pressure regulators at 5.5 psi. With a stock fuel pump, the minimum fuel pressure is at WOT. Fuel pressure should not drop below 2.0 psi. If it does, the fuel pump is bad. It’s not uncommon for a stock GM mechanical pump and almost all aftermarket electric fuel pumps to put out more than 6.0 psi at idle – this will cause a problem and you will need to install a regulator.

Your carb is probably a 1407(manual choke) or a 1411(electric choke). If your carb is in its stock form (factory jets and metering rods), I’d recommend the following:

1407 – Install part number 1431, .107” main jet and part number 1445 .065” x .047” metering rods.

If you have a 1411, Install part number 1430, .104” main jet and part number 1450, .070” x .042” metering rods.

I always replace the airhorn gasket (comes in a kit, part number 1472, includes cab to manifold gasket).

Depending on your mechanical ability, these changes can be accomplished with the carb on the engine but bear in mind that there are tiny parts and if you drop any of them down the throat of the carb – let’s just say you’ll be in a bit of a pickle!

Good luck and let us know how you come out!
Glenn