Normally my 355 idles at about 800-900, lately it'll fire up and run fine till about 5 minutes after i start driving it. It'll idle up to 1200-1500 and stay there. the throttle can be sitting right on the adjustment screw and it'll still idle that high. Kinda annoying when your driving through town and it starts powerbreaking the rear tires at stoplights...

I've checked for vacuum leaks and didn't see any, the line to the vac modulator sometimes slides off but usually the tranny just stops shifting, engine dosen't act any different...


Edelbrock 750 carb, Torker 1 Intake and no accessory vac lines, just the brake booster, vac advance and tranny line. Fuel pressure is at 8 PSI and it has a new fuel filter right before the carb.


Thanks,
Dave

 

is your high idle sticking on? mine did on my 1406. just had to be readjusted.
also, 8psi is way to much for that carb. i think it's supposed to be 6.5 max

 

Thanks, i used to keep the pressure closer to 6 but it seems that it runs better at WOT with the higher pressure. I backed it down to 6 today to see if that was causing anything.

the high idle screw is backed out so it shouldn't do anything... I also noticed that the spring i had on the choke to hold it open is now missing... maybe the choke was closing a little...

 

welp, it still does it...

after a while it goes back down to normal, usually when i slow to a stop it'll idle high then start to back down....

anyone think the vac advance could be sticking or something?

could there be some crud in the carb? carb's got about 200 miles on it..

 

could be too low of tension on the advance springs causing it, if they're not strong enough to close the advance, then the motor will idle erratically until the springs finally bring the advance back down.

 

I did put the lightest springs in the kit on there...

 

i'd toss the medium springs in there and i'm betting that will clear up your situation, the problem is the lightest springs don't have enough tension to close the weights, thus causing an inconsistent idle speed

 

Sorry to jump in here, but i have a similar problem. only my idle goes back down after a decent rev of the engine... it also idles around 1k-1200 until i blip the throttle 1 good time im not sure where to start.

 

how is your throttle linkage? any binding? also how's the throttle return spring?

 

You could have multiple problems, sound like it's maybe time to get that distributor re-built and curved correctly to your engine.

Then look at a real carb, Edelbrock Carbs belong in the scrap metal pile, won't ever work correctly, ever. The 750 is the worst of all of them all, fuel curve looks like a cross section of the Rocky Mountains, mid range lean out that Can Not be cured, Cracked main bodies leaking fuel into your motor as soon as they get hot, no adjustability.....a waste of hard earned $$$$.

Nice looking car, time to invest in making it run right.

{Edited by Moderator}

 

I know this thread is over a year old but this just shows how lazy i am. (and may provide info for anyone else with similar problems)


I finally found the problem today..

all 4 throttle plates were loose.. the 2 front primary ones were crazy loose, if you opened the throttle and let it snap shut they'd go crooked and bind the shaft open a few mm.

I backed out the screws and closed the throttle completely then cranked them back down. cleaned out the carb really well while i had it out and apart.

the car runs like a top now, it's too bad i still gotta sell it before winter.