[ss396si]

This morning I was tuning my adj. vacuum advance (I didn't hear it ping yet), the car runs great. So I come to a stop on the service road and i floor it. When I get to the light the car runs rough tach drops to 500rpm's. I then pull over the car smells rich and the engine is running rough and fuel pressure is 5-6psi. Driving home the rough idle smooths out as the rpms increase.
I have a 305 engine edelbrock 600cfm 1406 carb in a 69 chevelle.

 

[sqzbox]

Any pop or backfire when you mashed it? Could have blown a power valve if it didn't come with the check valve in the base plate to prevent it. Also, check for vacuum leak, a big one! and check secondary throttle blades and make sure their closed all the way. The secondary's have a tendency to stick
once in a while if not used allot. Good idea to spray the throttle shafts periodically with PB blaster and check for carbon build up in the venturi's where the throttle blades make contact.

 

[lg1969]

It is possible a piece of material could of enter in the float valve causing it to stay open slightly.

 

[sqzbox]

yeah. Especially if you don't have a good external fuel filter. Initial timing could have changed if the dist. clamp is not tight too.
The last thing you did was adj. the vacuum adv. control so you might want to re-check what you did and make sure that's not the problem.

 

[T-bucket23]

This morning I was tuning my adj. vacuum advance (I didn't hear it ping yet), the car runs great. So I come to a stop on the service road and i floor it. When I get to the light the car runs rough tach drops to 500rpm's. I then pull over the car smells rich and the engine is running rough and fuel pressure is 5-6psi. Driving home the rough idle smooths out as the rpms increase.
I have a 305 engine edelbrock 600cfm 1406 carb in a 69 chevelle.

Since you were messing with the vacuum advance, I would check for a broken vacuum line or maybe it is even disconnected

 

[Irelands child]

My personal history with Edelbrock Performer carbs - and it's fairly long (~1987), is that they are very susceptible to dirt, that they will run rough, flood and even occasionally stall. You need a GOOD 10 micron pleated canister filter to be on the safe side. The little bitty Russell or other pretty after market ones wont hack it as for the most part they are a big chunk strainer.

Of course - look for a cracked vacuum line as well.

As far as adjusting a vacuum advance with your handy Allen wrench - without a Sun (or similar) distributor table you are only in the guesstimate mode

Dave W

 

[sqzbox]

Some of us have to get by with timing tape, an adjustable timing light, and a buddy to work the throttle and watch the tach. It's called a "po mans dist. bench" 10-4? :thumbup:

 

[Irelands child]

Some of us have to get by with timing tape, an adjustable timing light, and a buddy to work the throttle and watch the tach. It's called a "po mans dist. bench" 10-4? :thumbup:

....and totally wasting your time - but what ever floats your boat :thumbup:

 

[sqzbox]

:embarrass

 

[American Muscle]

I just had this problem two weeks ago out of my 305 and even posted questions. My problem was a trash filled carb. Took the carb to my local builder and he said it looked as if it sat up awhile. Installed the carb with a new breather and an inline fuel filter and have never looked back. Also Im not for sure if you do or not but dont run 83 octane, thats just trash waiting to happen.

 

[ss396si]

I just changed my fuel filter and now the car won't idle at all. I have to keep my foot on the pedal to keep it running.

 

[lg1969]

Sounds like a vacuum leak

 

[ss396si]

How can i spray the vacuum lines with carb cleaner if the car wont idle?

 

[sqzbox]

At this point, I'd be looking for evidence of sugar. Seen it happen just like this. :sweat:

 

[lg1969]

Yes you can, just make sure you have a buddy with you. check the PCV and brake booster check valve if you have power brakes.

 

[Irelands child]

..........or you broke some more crud loose and sent it into the carb.