lots of new stuff but runs poorly

[m_m70]

OK so I just finished up installing new heads (TF 170s), long tube headers, edelbrock performer manifold, and edelbrock 1802 thunder series 500cfm carb.
Seems like the carb is running rich. Set idle with a vacuum gauge and seems to be holding steady at 20. I have the timing set at 14.
the truck wasn't drivable yesterday when on test run. zero power under load. today I adjusted the power valve to the bottom hole and got it out on the street. serious bogging off the line but when it decides to go it moves! IT does have the popping exhaust on deceleration but I have the exhaust clamped in all mickey mouse like (sure there's leaks there) until I get it to the muffler shop this week.
I know the screws in the front of the carb only adjust the idle mixture. I guess I have to buy the calibration kit and change the rods and springs. Does this sound right or should I be looking at something else?

Thanks!
Mike

 

[SHX669]

What type of ignition and what distributor?
SHX

 

[m_m70]

running the pertronix 2 and pertronix dizzy as well. both have under 500 miles on them.

 

[broncnaz]

The 500 should be jetted fairly close but it sounds like you may be lean. A tuning kit is your best bet carbs are rarely spot on out of the box. Plus with all your mods you have a lot more airflow thur the engine. and that carb came tuned for emissions not performance.
I would probably try backing the timing off a little as well to much intial timing can make the engine seem like its running rich but thats only because the spark is coming in to soon and your not getting a full fuel burn.
That bottom hole you moved linkage to is to the accelerator pump not the power valve. Edelbrock uses step up springs for the metering rods as the power valve. Most of your bogging may be due to the wrong step up spring.
Lean mixtures tend to cause bogging no power and backfires. rich mixtures are almost the same but have to be really rich to cause the bogging and power just wont be at the max.
If the tuning kit gets rid of most of the bog but not all. Then you may need a larger accelerator pump squirter. emissions carbs tend to come with small ones that cause some the off the line bogging.

Is the pertronix getting a full 12volts of power? If not that could also be the issue.

 

[m_m70]

thanks for the response. I'll order the calibration kit tomorrow as well as check the voltage to the dizzy. I know I was getting full voltage before I tore it all down but who knows. I do know I haven't checked it;D
the bog is pretty severe but once it seems to catch up with itself it's really smooth.
Also thinking it may be a vacuum leak as I have read that they can give some fits as well. Sprayed carb cleaner around the carb and the front and back of intake and didn't get any noticeable changes so I may be good there. Would a vacuum leak show up on a vacuum gauge??

 

[broncnaz]

A vacuum leak would show up but your reading is pretty high and a leak usually shows up as lower vacuum readings it would have to be pretty big to cause the bogging issue. Usually vacuum leaks cause the idle to be high and the idle mixture screws to have almost no change to idle quality when adjusted.
Was just making usre on the pertronix cause if its powered using the stock igintion wire you will not get a full 12 volts after the key has been on for a little while.

 

[jckkys]

As broncnaz said you sound like you have a lean condition. The tuning procedure for the AVS is identicle to AFBs. Neither has a power valve. Enrichment under load is provided by the metering rods. Your AVS may need stronger step up springs. The stock ones on a 500CFM are orange or 5"Hg. My 500 ran much better with the plain spring that moves the rods at 8"Hg. The engine is more responsive. The stock primary jets are .086". If stiffer step up springs don't work try the next size larger or .089"s. They worked better in my 500CFM AFB.
The accelerator pump rod should go in the center hole in the arm. A 500 doesn't need a big or long accelerator pump shot. If yours needs more fuel try going from the stock .028 nozzle to the .033".
Do changes one at a time so you know how each works.

 

[m_m70]

thanks guys. I will keep posted on outcome.

 

[m_m70]

update

OK well I changed the springs and rods. I kept the jets the same per chart and the difference is amazing! Honestly I was pretty skeptical because it just ran so bad. It couldn't make it back into the garage on it's own power?:? but in the 5 minutes it took to change the springs and rods it goes like a scalded ape!
Thanks guys! Seriously would not have gone in the right direction without your guidance.
Good times!
Mike

 

[Justafordguy]

That's great new, at least it was something easy.