General Category > Quadrajet Carb Talk and Tips

POE changes for a 4-speed

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Cliff Ruggles:
The reason they are below or directly in line with the flaps is so the fuel doesn't "puke" out on top of the flaps when you go quickly to full throttle. 

It's not typically a  problem area right to start with, but for sure we want as much fuel as possible from the secondary POE system to enter the intake manifold when the huge secondaries come on line to help prevent a momentary lean condition (hesitation/stumble/bog). 

Also keep in mind that the intake does get a nice shot of fuel from the fuel in the passages feeding the main nozzles, but it is often not quite enough.

Even more important that POE is having the link from the pull-off adjusted correctly to keep the flaps from "whipping" open.  The secondary tension spring is not strong enough to do that for us so we need the pull-off to dampen the opening every so slightly till fuel starts flowing as there is no accl pump system for the secondaries.

I'd note here that factory pull-offs had calibrated release times to help us out.  Most aftermarket replacement pull-offs are not timed correctly and often things aren't adjusted correctly during the rebuild either. 

There there's the crowd to removes the link from the pull-off to the secondaries and tries to tune with the spring.  That NEVER works out well although  folks doing this think that the "kick" they feel going to full throttle is somehow better than smooth/seamless transition..........

Dano3500:
Thanks (as always!) for the explanation! I've seen your comments on the linkage:).

Do you know why this design was mainly used on manual transmission carbs?

So on a high perf., or even stock 350 4-sp. (seemingly any engine?), is there any reason not use an air horn with POE holes below the flaps? Can an air horn w/them above be modified to have them below &/or is there any tuning to be had by enlarging the holes?

Cliff Ruggles:
The POE exit holes can always be relocated below the flaps.  It's actually not all that difficult.  First you have to block the original holes, then re-drill new holes under the flaps. 

To do this here I melt a little lead from  wheel weight into the supply holes after removing the tubes.  I then drive the lead down with a flat punch adding if necessary to make sure the upper holes are plugged. 

Next using a small sharp center punch light up with the passages below the flaps and make a mark deep enough so your small drill bit doesn't slip (drilling at a slight angle).  Drill thru until you connect with the fuel supply passage.  You have to drill slowly and make sure the chips clean out or the drill can load up and snap off........

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