vacumn secondary spring function variables

[fizz]

Simply, I have a 10-1 compression 493, trick flow 240s, solid lifter cam, headers, six pack. Without getting too complicated, to eliminate a bog, it likes the 50cc accelerater pump with the brown cam, and the black springs in the vacumn pods. Is it something to do with engine size and amount of air volume that is making a condition where it requires heavier vacumn springs than would be expected(from what I normally hear people running)

[c00nhunterjoe]

6 packs can be tricky and i rarely see people that can tune them. Hell, most guys struggle with 1 carb....
Most carbs ive seen benefit from the extra reserves the 50cc pump gives, especially in your case with more cubes. Those trick flows will feed the bigger cubes better then eddys, if youve got the bog gone and shes crisp throughout the rpm and outboards, great job.

[BSB67]

Gear, converter, car weight, airflow/vacuum signal will effect rate opening relative to engine needs.  And,  it is usually opposite from what you think might work.  Faster, lighter and more gear cars will want stiffer springs.

Higher fuel level and more open/rich idle mixture on the outboard will help.

Don't try to cover it up by putting more main jet in.

Depending on your car's set up, there is a fair chance that if you slow down the outboard carb opening rate to reduce a slight hesitation during street operation from a roll,  you've probably also slowed the car down in 1/4 et and mph, and maybe by a lot.  Said differently, if you want the best 1/4 performance, tune to the fastest outboard opening at the track without a hesitation,  but it will probably hesitate on the street from a roll.

[fizz]

BSB67, after I posted, I found an old thread on another board(2011) talking about this. You had good advise on there. Since these carbs were set up on a tuned drag car in the 70's, I need to inspect the air bleeds. I was dealing with a pretty severe hesitation dropping the throttle from a dead start.

[PRH]

You may want to verify the kill bleeds in the secondary carbs haven't been plugged.

[BSB67]

You may want to verify the kill bleeds in the secondary carbs haven't been plugged.

This would do it.  If they are plugged, you likely can remove the plugs.  But consider drilling them instead.  This way you can trial up to the size that works best for you.  Start at 0.030" or so, and go up from there.  I think the later model carbs came with 0.040 - 0.042.  Original 69 carbs were like 0.050".