really high idle

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razorback

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ok so i got everything figured out..but the car idles really high when warm. i put the fast idle screw all the way to slow it down and the idle adjustmentn screw too.. (the further out it is the lower the idle correct?) what else do i need to check? recheck timing? adjust afr?
 
if you close the air mixture screw and the motor still runs, you have a vacc leak. you need to check. start with hoses and then go to gaskets. good luck
 
i shouldnt have any vac leaks.. i have only the required hoses, the carb to valve cover pcv and the vac advance to carb. i dont have the brake booster hooked up yet, but there is no loose hoses laying around. no gaskests should have leaks, i dont hear any thing that would sound like a vac leak. i guess i need to check the advance on the distributor.
 
the carb is a holley 600cfm model with elec choke. do not know if that matters.
 
razorback said:
ok so i got everything figured out..but the car idles really high when warm. i put the fast idle screw all the way to slow it down and the idle adjustmentn screw too.. (the further out it is the lower the idle correct?) what else do i need to check? recheck timing? adjust afr?
Click to expand...
Just recently on a drive in the wifes 67 dart 318, (I can't belive I wasn't working on it) We experienced a sudden run on comming up to a turn made the corner RPM's up high pulled over. A small black vacum cap had fell off of a tree. Funny thing was I went looking around the parking lot for a small hos, screw, etc. Wife asked what was I loking for. I told her. She reminded me earlier in the week I found 7 or so blue vac caps in a parking lot and they are still on the floor in the back! Dang she did it to me again@! Anyway we got home and I replaced all caps hoses!
 
Did you check the secondary plate to make sure it's not cracked open too far?
 
ill recheck the vac lines, but i dont know what else there is thats not connected. and how would i check the secondary plate? whats open too far?
 
how open should it be when its cold? completly closed?
 
just enough to lower idle speed, did you check your timing? usually raising initial raises idle speed
 
before i started it i had it at tdc, then started it and used a timing like to make it line up.. i had help, but he said it was right.. its a stock 85 360 with holley street intake and headers..
 
get some carb spray and spray around the intake and heads see if the pitch changes and at the base of the carb also...if what carb is it?
 
i adjusted the distributor and it runs alot lower now than it did, sounds almost right at what it should sould like i think. i have a video of it running, but its 19mb and im on dialup so it would take forever to upload it to youtube, ill try and resize and upload it later after i resize it.
 
aslong as theres no ping, and the idle is were you want it, should be fine
 
Vacuum advance distributor? If so, is the hose connected to a timed port? Does it idle ok then idle high after revving the motor; or does it just idle high without goosing the throttle?

I'm thinking the advance in your initial timing raised your RPM's up enough to increase the vacuum open and kick in your vacuum advance. Or if the hose is connected to the manifold port, then the advance would probably kick in at idle, depending on your vacuum at idle. If you've had the hose disconnected or it doesn't have vacuum advance...disregard my feeble attempt to solving your problem.

I had a fun time playing with a vac pump connected to my distributor and seeing where the vac advance really kicks in. I ended up with it set to kick in at roughly 12 1/2 lbs of vac, car idles with around 11 1/2 lbs of vac.
 
Your choke is on in that video. You should try setting everything at normal operating temperature and the choke off.

You can't set your curb idle if that choke plate is anything but wide open.

If it won't go wide open you need to adjust your choke so it does.

If you are setting the curb idle with the choke on, when the car warms up and the choke plate opens your idle will go through the roof.

I think trying to set things with your choke on is 100% of your problem.
 
I'm with burntorange get a can of quickstart spray carb base,intake gaskets,brake booster etc until it revs up even more. Vacuum leaks can be hard to find.
 
i bought new vac hose yesterday im going to replace it in a little bit, wont get a chance to test the trouble shooting tips til wednesday when im off again. i have to fix my leak out of the bolt holes on the front cover today and let the sealant dry before starting it up again. also realign my radiator, i think its too low, so its not cooling/flowing properly.

the carb is a holley 600cfm 80457 or 80783s electric choke rebuild by an ebay seller that had really good reputation.
 
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