After installing a new Edelbrock 600, all was well for a few days. All of a sudden it will run perfect until the choke opens. With the air cleaner off I watch the choke open as the engine warms. As it gets closer to full open the engine starts missing and running rich. At full open choke it will stumble and quit.

I have checked for vac leaks and even reinstalled the carb. Same problem. What am I missing and why after a few days would this occur?
HELP!!!!!!!!!! I will never make it to the show a this rate.

 

those carbs dont like high fuel pressures .. you may need a regulator.. pinch off or remove and block the fuel line and see if it runs better for a moment till it dies ... and the idle adjusting system is very finicky..

 

I agree with Hoss and I would like to ask some dumb questions.

What rpm is the engine running at with the choke engaged and what rpm is it running at when it dis-engages?

Also I assume you set the air fuel screws with the engine warm with the choke off?

Also did you mention a large cam..any cam specs?

What is happening that tells you its running rich? Black smoke or miss-fire? Fuel smell?

Last one, distributor type, vac advance or centrifical advance?

Dumb questions I know but they could help solve the problem in case it is more that fuel pressure related.

What part of town is the car in just in case it cant be solved here on line in time for the show. Perhaps Hoss, myself or another old school hot rodder could stop by and help figure it out.

 

Engine is 100% stock.. The idle mix screws were set while cold but the car will miss when rev'd as well as at idle. It idles at about 800 and lowers when the choke opens and it starts to run rough. It smokes fuel smoke all the time now but didnt smoke at all prior. I will try and pinch the fuel line and see what happens. What pressure rating does a stock stang fuel pump have?

My Vac advance-can has a line going to a 3 prong nipple on the rear of the intake. That looks odd to me so I moved it to the ported vac nip on the carb. That change didnt seem to do anything at all.

If worse comes to worse are there any members that do house calls? I would gladly pay with food and drink.

There is a 1" spacer under the carb with several large vac line that connect to the emmisions. They are in poor shape but I dont think that would cause my problem. I may need to just dump this intake all together..............

 

Where is the car located? Maybe its close to a member. 4-7 PSI is probably all you need if you are not reving it too high. What fuel pump do you have? I assume we know it does not have an ignition miss? No plug wires have been moved ect? It is hard to ask some of these questions without sounding insulting. If its close I would be willing to look at it. If its something simple it wont take a long to figure it out. Let me know

 

I am located in Madison, 5min away from the DQ. Dont worry about any questions being insulting. Its the easy things that fix most problems. I feel confident that its not ignition related but will look at that as a last resort.

My pump was replaced by the p.o but it looks like a cheapie stock repalcemet. I did pinch the line and the idle went up and it ran perfectly. It stopped smoke'n and all was well. After i let go of the line, 10 seconds later the prob was back. I couldnt pinch it long with just fingers, I had to use pliars.


Ok there is hope. We are getting closer.

 

Sounds like you could be on the right track!

 

I dont have a way to ck the pressure but I will order a pressure-reg straight away.

 

That 3-way nipple you mention is to change the vacuum to the distributor depending upon coolant temperature. You can hook ported straight up to the distributor and time it.

Depending upon if you still have your emissions hooked up, the EGR plate leads vacuum lines to the charcoal canister. You should also have a vacuum line to the EGR. You either need to fix all of that, or junk it. I did notice a slightly better vacuum signal with the plate.