SBC HEI voltage
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Thread: SBC HEI voltage

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    Compulsive chicken choker English Impala's Avatar
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    SBC HEI voltage

    My constant rich/rough running problem on my Impala persists.... to the point where I've got through three sets of spark plugs just while having it running in the drive.. The car isn't driveable....

    The wiring loom in my car is new, but is for the original set-up which had a resistive feed to the distributor (rather than a seperate ballast). The permenant feed to the distributor is 9 volts. I have a feeling that a HEI should be 12 volts. Is this true? Could this be giving me a weak spark leading to running too rich???

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    Off the Xmas card list kapri's Avatar
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    I don't know the answer to that one Gary for your engine but Antons Buick V6 HEI runs without a ballast resistor.

    On a slightly different tangent mechanical or electric petrol pump ? Also genuine HEI or aftermarket, if so which.
    Last edited by kapri; 18-01-2010 at 08:02.

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    Compulsive chicken choker English Impala's Avatar
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    Kev, its electric, the cam in this motor doesn't have a lobe for a mechanical pump (guess how I found out.....). I don't know what make of pump it is, it was new & got it off 32 Chris.

    I'm on my third carburettor, initially tried two 600 Holley's (not both together) but now using a 600 Edlebrock. I know that a 600 is slightly too big for a 305, but the way the car's running you'd think there were two of them trying to feed it.

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    Dragging not Bragging vince-305's Avatar
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    Gary

    i replaced my loom for a mini one in mine which im 99% sure has 12v to the coil

    I sorted most of my running problems on my 305 with the 600 edelbrock but i had to change the stock inlet but have found that it is more juicy than it was

    I havent fitted the 500 jets in mine yet tho to see if it makes a difference (with the new manifold)
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    Off the Xmas card list kapri's Avatar
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    Holleys don't like more than around 5 psi. I had poor tickover on a 302 that turned out to be excess pressure just lifing the floats enough to let excess fuel trickle into the manifold. It would fire up Ok and would idle normally while the choke was working then it would start to get all lumpy and 'fuely'.

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    I'm Not Jed Clampett stueeee's Avatar
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    You definitely need 12V for the HEI. Is It a Delco or aftermaket HEI? The motor's response was hugely improved (especially at high revs) on My truck when I changed from the stock Delco unit to a Procomp HEI setup.

    If you've had the same running way too rich problem with a few different carbs, I think the problem is likely to be excess fuel pressure as Kev says. If you've got a pressure regulator it would be worth lowering the pressure and see if that cures the problem, if you don't have a regulator it would be worth fitting something like a Filter King IMO.
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    Official RnS Addict Steve 5-6-7's Avatar
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    Exceeded sell by date Plumpcars's Avatar
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    I think it's all been said really. If it's a GM HEI it needs 12v. You also need to know what fuel pump you have and what it's output pressure and volume is. Is it an injection pump?. A 600 carb will work on that engine without being that rich. I ran one for some time and it was crisp and responsive and co was fine. CFM size does not neccesarily relate to mixture strength and certainly does not lead to a mixture as rich as yours. If it's that rich you may want to change the oil once you get it sorted as well.

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    Dragging not Bragging vince-305's Avatar
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    Gary

    Fuel pressure wise Im using a holley blue top pump and regulator is set at 4.5-5 psi (i seem to remember it was you that told me to lower mine) ive had to put a permenant gauge on mine as every now and then the reg seem to allow full flow 8+ psi and push past the floats and overflow the carb (i mean overflow as in out the top of carbs and over both sides of the engine while driving or sitting at lights)
    Bit'z 'N' Piece's
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    Compulsive chicken choker English Impala's Avatar
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    Thanks folks. Vince, I was running a gauge & regulator on mine, but it looked awfull so I removed it & the car ran the same, but seems to have declined over the last few months. I'll put it back on & bypass the ballast wire to give 12volts & see what difference it makes.

    I changed the oil just before Xmas & got out 1.5 times what went in!!!!

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