Small Block & Big Block Chevy Specific - Holley carb/ high idle situation

Okay, well recently just got done with a new crower cam and vortec heads, a bigger vac secondary carb and a pro products typhoon intake, basically my proplem is a really high idle, and i know what everyone is going to say that i have a vacuum leak, well i capped off all the vacuum ports and went around the intake and carb with carb cleaner and nothing. i really thing this used carb i picked up from the swap meet has an issue, can anyone give me some insight that may lead to solving my proplem.

thanks luke

Check the timing, also does the carb have a choke? Its possible to for a carb to have an internal vacuum leak, swap your other carb back on and see if the problem continues.....

the carb does have an electric choke, but i manually tied it open, i need to get a timing gun on it to set initial timing, but i cant get the thing to idle anywhere near 800. i am going to try swapping the carbs tommorrow, thanks for the help

The choke should have a little red arm that may be broken or stuck, it opens and closes the blades not just the flapper up top check that.

Next take a wire from the battery and hook it to the choke and start it again, also just try backing the timing off a little and see it helps. Just a temporary jumper, if it works hook on the a keyed power source.....

Does the dist have a vacuum advance pod, if so pull the hose off and see if theres a change.....

oh shit, i think your right, i do remember that little red arm sitting behind the choke coil and such, i bet that thing is just stuck, i did pull off the hose still the same. i will try the jumper wire as well. thanks for all your help man,i used to know these things really well, but as they say when you dont use it you lose it, its been about 5 years since i messed with sbc shit.

Lemme know if you need any more help.....

is sure will, im going to give it another shot tonight, do you have any reconmendations as to where i should start intitial timing? i was thinking around 8 or so degrees advanced just until i get the carb tuned once the cam breaks in.

12* intial and 34-36ish total

on a holley 4v, the secondary plates have a stop set screw. If i remember you can only access it by taking the bottom plate off the carb and accessing the main body from the bottom. This set screw should let the secondaries close all the way, but not too tight to where the secondary plates stick and bind when closed. If this set screw is holding the secondary plates open just a little, it'll cause you're high idle and no other (reasonable) tuning will get the idle down because too much air is allowed to flow past the secondaries at idle.
Other than that, your regular throttle set screw you can back all the way out so the main throttle plates are completely closed, and I don't think any of the transition slots in the throat should be below the throttle plate. 1.5 to 2 turns out on the idle mix screws, if idle doesn't drop to 600 or less then you have air entering somewhere somehow.

for initial timing and break in, anywhere from 8-14 is the norm at idle, closer to 8 if you have a rich mixture, if you lean it out then you can advance it more. throw a vacuum gauge on the manifold if you can and set you're timing at low idle then adjust the idle mixture screws to give you highest vacuum reading.
http://www.chevyhiperformance.com/howto/45638/index.html

hey great advice, after messing witht the red arm, i got the idle down but still cant seem to get it below 600, but im okay with that until i see the a/f if your right ill have an extremely lean a/f at idle, the vacuum thing is a great trick, last night i got it idling and adjusted the a/f, but im having a hard time with the timing due to a professional products balancer,the numbers are hard to read, im just going to make my own cyl 1 tdc mark, and then use a gun with a dial rather than just straight timing gun, im slowly getting everything worked, out, its been to long since ive done old school stuff, i forgot how much i enjoy doing my own tuning and adjusting,

Get some white out or white paint and mark the damper, as far as the above guys advice on less timing for a richer mixture and more timing for a leaner mixture WTF are you talking about man where did you get that from???? Rich and retarded creates a TON of heat in the engine and can make the headers GLOW RED even at idle. Thats not good advice at all! If you dont know what your talking about dont give someone the wrong advice give NONE.....

PLUS your cam is WAY too big to idle at down 600 rpm, you need a 900-1000rpm idle in park and about 850 rpm in gear or its going to run like a dog, load up and want to die. Turn the screws all the way in and back them out 2 turns, start it up and with the engine at operating temp slowy turn the screw in until you get the smoothest idle if its starts to chug back it back out until its smooths out again if the idle raises go the other way until you find the sweet spot....

You can call me again if you need me to walk you through it on the phone......

you forgot to mention lean and advance will burn pistons,
you're taking it out of context,
relatively speaking if you lean out a mixture then in order to get complete combustion to happen at the correct time the timing needs to be advanced, if you go richer then it will burn faster so timing does not need to be as advanced.
Here's one writeup explain it http://www.corvette-restoration.com/resources/technical_papers/Timing101.pdf


It's not like said to screw out the idle mix screws 4 turns and set timing ATDC, and at idle no load which I thought this was about you're not going to glow anything red no matter what mixture or timing you have, so a WTF back at you tough guy ! :P

Might want to check to see if the flappers are rubbing the intake. I put a Holley 750 v.s. on the other night and had the same problem. I have an Edelbrock performer intake and had to slightly move the carb around while looking down the throat to stop the flappers from rubbing, then tightened in place. Really tight fit.

thats a good point as well, i still have not got it to idle low enough that the motor will die, i am running a pro products intake so im leaving no options closed, i have heard the mag's rave about the cost and quality of these manifolds and parts, well you really can see the differance compared to real performance parts company's compared to the shit pro products makes, makes less power, fits like this, looks like shit, my balancer has already started to come apart,