L78 Holley Rebuild...

[SS427]

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Next issue was the Borg/Warner needle & seats that had been previously installed. These units are responsible for more junked float bowls than I can count.


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That made this thread worth the read (in case some of you didn't think it was already ). I KNOW that I have used the BW needle and seat on many rebuilds and have suffered many a floading condition and/or leaking afterwards. I never gave the needle and seat a second thought as being the culprit. Thank you very much for that information. Now if I can only retain that little tidbit of information in my pea sized brain.

[VintageMusclecar]

Perhaps I should clarify a little bit in regards to the B/W needle & seat issue;

It's not so much the fault of the component as it is the potential for damage by the installer. If you've ever taken notice, you can only thread a genuine Holley needle & seat down into the float bowl so far before the nut dis-engages the top of the needle & seat, preventing you from turning it down any farther where it could damage the boss where the O-ring seals.

On the B/W unit, due to the design, you can easily thread the needle & seat down far enough to do damage since the needle & seat itself contains the means of adjustment (screwdriver slot) as opposed to the 5/8" nut used on the genuine Holley part.

If someone was having issues with the carb that led them to believe the float levels might've been too high (such as a heavy or sinking float), one might try to lower the adjustment to the point where the extended threads on the B/W component start to thread themselves into the lower O-ring sealing boss, which in turn ruins the float bowl.

The other common result of the B/W needle & seat is stripping needle & seat threads right out the top of the float bowl. If you'll notice, this design has a reciever groove in the bottom of the lock nut. The nut is only designed to go on with this reciever groove facing the float bowl to compress the O-ring on the top of the needle & seat to seal it externally. I can't begin to count how many of those nuts I've seen installed upside-down...the result?...a leaky needle & seat that naturally prompts the mechanic to try to snug the nut down just a liiiiiiiiiiittle more to try to stop the leak. The result?...cranking the nut down only serves to draw the needle & seat straight up out of the float bowl, taking the bowl threads with it.

These are just a few of many reasons why I'm so adamant about using only OEM quality parts in my rebuilds & restorations.

Hopefully this will save someone a float bowl or two somewhere down the road.

Eric

[Jeff H]

Carb looks much better with the correct needle and seat and primary bowl. I sold my 4557 months ago for money to continue the restoration the JL8. It was dated wrong for my car anyway. I would like to get a more correct looking Holley 780 for my L78 and don't want to waste money on the 3310 since it's been messed with already. If I find a decent carb, I will be sending it your war Eric. Can't wait to hear how well this Nova runs with the rebuilt carb!

[Rixls6]

Great read.
Thanks Eric for the "insider" info about the needle & seat.
All my carbs would definitely be going to you when they need restoring.