by ratio411 » Tue Jun 22, 2010 3:48 pm
I am not going to get into detail, mainly because I haven't worked on a Quadraflood in a great many years...
But I will give you a couple pointers...
1: Accel pump tuning... Like any other carb, the accel pump needs to be tuned such that it delivers fuel into the venturis at the slightest movement of the throttle.
If there is any delay at all, between the movement of the linkage and the squirting of fuel into the carb throat, there will be a bog or at very least soft throttle response.
2: A Quadrabog is not a typical mechanical secondary carb, nor is it a vacuum secondary. The Quadrajunk is a hybrid of the two designs.
The secondary throttle plates open mechanically with progressive linkage, just like a double pumper Holley. However, like the vacuum Holley, it has no accel pump shot upon the opening of the secondaries. It relies on the upper 'butterflies' to keep the secondaries out of play until the engine is TRULY ready for the extra air flow. There is a spring and weight system in the upper butterflies that keeps them closed until the engine reaches a point where it can open them itself as needed. This is where my 'tip' comes in.... This carb design is EXTREMELY sensitive to the adjustment of the upper butterflies. You want them adjusted just a bit on the tight side. If you have them adjusted to open too freely, the engine will pull them open before it is ready for the extra air, and create a bog. If you have ever heard of someone claiming they can "feel" the secondaries kicking in, what they are actually feeling is a bog created by the secondaries opening too soon. A properly adjusted secondary should NEVER be "felt". It should be a smooth transfer of the butterflies opening only when the engine has suffecient flow built up in the secondary circuit to both overcome the butterfly springs AND flow fuel through the secondary sytem. There is no second accel pump, so fuel/air MUST be moving within the secondary system when the butterflies open, or you just have a momentary vacuum leak, aka bog, until the engine gets the circuit flowing.
Make sense?
Sorry so wordy, but if you understand what is going on in full, it helps make carb tuning less of a mystery.
1978 Monza Spyder
SBC/M4
White over black
Father was original owner.
I rode home from the dealership in the car when I was 8.
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