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Author Topic:   500 holley problems?
labman
Member
posted August 15, 2002 08:29 AM
350 oldsmobile engine with a 500 holley 2bbl
on a stock cast quadrajet intake with a straight 2 hole non adjustable aluminum adapter plate located directly above the back big holes in the intake runs great up to 4000 rpms then starts popping and spitting and wont go over 5200 rpm. If I bolt on a quadrajet carb it runs like a top well over 6500 rpm without a bit of a miss. I have tried 3 different 500's, 1 new off the shelf, 1 new from a race shop and 1 off of a friends car that runs fine. What can be wrong?


KPLugnut
Member
posted August 15, 2002 08:46 AM
First, check to see that there is no interference between the butterflies in the holley 2bbl and your 2 holes in the adapter. If it is limiting how far they can open due to misalignment, that could be it right there, no matter what 2bbl you bolt on.
Next check to see that there is room for your accelerator pump arm and linkage to clear the adapter and that it's not hitting on the adapter.
Also, could there be any vacuum leaks around the adapter and intake? Particularly the front/primary quadajet holes. One way to check is let the car idle and spray WD40 or carb cleaner around the adapter and see if the idle changes.
Also, check that your throttle opens fully when the pedal is put to the floor.

I know these things may seem silly and obvious, but it can't hurt to ask since you didn't say what you'd already checked.

Hope that helps,
KPLugnut


labman
Member
posted August 15, 2002 10:03 AM
I have already checked all those things numerous times I wish it was that simple. Thanks


KPLugnut
Member
posted August 15, 2002 10:16 AM
Give use some more info on the motor itself as well as where you're jetting and setting up the 2bbl carbs. They could be too lean for that motor, or just set up wrong.
Also, there isn't a problem with fuel pressure, is there? 6-7lbs at idle is best for the 4412. However, the quadrajet is more temperamental with fuel pressure than the Holley, so that might not be it. Something to verify, tho, because a quadrajet can function properly with lower fuel pressure than the Holley, so if you're running out of fuel at higher rpms, the Holley will "tell" you before the quadrajet will.
And since the Holley is sitting so far back
on the intake, make sure you aren't arc'ing a plug wire on it or something. Probably not the case, but can't hurt to ask....

Anyone else got any thoughts?

KPLugnut


JDPRACING
Member
posted August 26, 2002 04:53 AM
I had the same problem with a so called race carb.After 3 times to the track i took it apart my self.It had .015 of warpege on the metering block from someone over tighting.It makes an internal leak that carb spray from outside won't pickup.Take it apart ,check all parts with a straight edge.You can't have more than .004".If so find good flat file and hand mill parts.


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