Running rich
 

I have black soot on the ground behind my car where the tail pipe turns down. I'm assuming its running really rich and was wondering what a good baseline jetting for a holley 700 would be?

I don't have a wideband O2 sensor and dont have the funds for it right now.

What is the best way to tell if a car is running rich during idle, mid rpm, and wide open?

Almost forgot if i get into it off a corner it blows quite a bit black smoke but it doesn't smoke while driving or at idle.

Re: Running rich
 

holley's website has all the specs for their carbs. a rich condition is not always the carb though.

Re: Running rich
 

What else would cause it? The carb is all set to stock specs except for the squiters, would those be a cause?

Re: Running rich
 

make sure the power valve is good (and correct vacuum rating) and the pv gasket is good. if the vacuum at idle is 10"+ use a 65pv, less than 10 divide your vacuum by 2. make sure fuel pressure is below 7.5psi and the fuel level is slightly below the sight plug with the engine running. some people say right at the bottom but it will be rich. also if you've had the metering block off of the main body more than a few times and did not replace the gasket you should replace them. I always run a flat file (just a few passes) over my main bodies to reduce the high spots. once you get the engine running, run the idle mixture screws all the way in, if the engine does not die you need to drill the throttle plates. one small hole in each primary. this will allow more control with the idle mixture screws. and the squirters will need to be set at 0 lash after the idle speed is set. if you change the idle speed you need to reset the lash to 0. bigger sqirters than a 37 need a 50cc pump. now, once your carb is perfect i can tell you what happened to me when i built my first race engine. this is about "what else could it be?" i had a too small intake gasket causing a major restriction of air/fuel flow into the engine. it idled too rich and too lean under a load. no matter what i did to the carb i could not get it right. i pitty nascar engine tuners when they have to tune restrictor plate engines.

Re: Running rich
 

with the power valve rating, here is a rule of thumb i use. if i have a cam that has a low rpm range say idle-5500 or 1250-6000 or has a smooth idle i use a 65 power valve. if the cam has a lopey idle i start with about a 25 or 35. if your unsure why the power valve is so important here is why. the power valve is closed (allowing no fuel enrichment) by engine vacuum. at WOT the vacuum drops. at idle, lets say you have a very lopey cam, you have 4" vacuum. if you have the standard 65 power valve it will not close causing a very rich idle

Re: Running rich
 

It now has a 65 powervalve and my vacuum idle is about 5" to 6" depending. thanks so much for the help i have the float bowls set already to just under.

The idle thing is a little funny because it doesn't die with them all the way in so i will drill a hole in each primarys. What size dril bit 1/16 or 1/8 to start?

It already has a 50cc pump what cams should i use with secondary 37 squiter and 25 squiter in the primary?

Re: Running rich
 

if you have the 65 power valve and your vacuum is less than 10. remember you take your vacuum and divide by 2. since your vacuum is around 5-6 i recommend a 2.5 (25)pv. i should have mentioned that the holley pv part numbers exclude the decimal. 25pv=2.5" vacuum, 35pv=3.5" vacuum and so on....

Re: Running rich
 

No biggy i figured it out when i was look at them.