[cobalt327]

The idle speed change/stalling when the power brakes are applied are possibly pointing to a bad p/b booster diaphragm. The cure if it is, is a new booster.

Remove the booster hose from the carb or intake, then plug the fitting so there's no vacuum leak. CAREFULLY see what happens when you apply the breaks. Do not take it on the road like this- the brakes will be very weak/too marginal for a panic stop.

[87monte385]

alright, that does seem like that could be it. but yesturday was the first real drive with it, because i just put in a new radiator and now it isnt getting hot anymore, when i was driving right at about 2000 rpm the motor started to break up and was popping, and when i came into town and started to slow down i down shifted and the car did NOT want to stay running. i was coming to the last part of the drive and the motor barley stayed running and when i pulled into a parking lot i slowed down and it died.. another issue is everytime i start it, i always have to have it to the floor otherwise its wont go. im not sure if its a jet issue because the jet size is only a #67... the car especially breaks up bad when i give it more than half throttle, right about when the secondaries start opening... I really want to thank all of you for your help! let me know what you think..

[cobalt327]

You need to (by looking at the plugs) determine if it's too rich or too lean- both can cause the symptoms you describe.

I'm more leaning towards lean, because too rich is accompanied by black smoke from the pipes and will smell rich.

If you're comfortable w/how the advance curve is set up, I would determine for sure (plugs) that it was lean. Then I'd get a kit w/the necessary gaskets and I would take the carb apart looking for the problem.

You can start with removing the sight plug to be positive the fuel level is correct. If it is, remove the bowl(s) and determine if there's anything plugging up the jets or any problem w/the float assembly. Keep looking until you find a cause.

There have been numerous reports of the shiny plating sloughing off and plugging orifices- if you find that to be the cause, you are going to have an ongoing problem w/the carb in all likelihood.

The jetting for a 650 DP should be in the area of 67/73 w/a 65 PV.

[87monte385]

i will try all of this! thank you

[Overdriv]

If I missed it, sorry, but what is your fuel pressure at idle and when it starts to break up?

[87monte385]

fuel pressure at idle is about 5-1/2 to 6 and im not sure what it is while driving i dont have an external guage. the fuel pressure regulator is the summit brand one that is actually stamped "holley" and i have the stock fuel pump on. i had an edlebrock high flow fuel pump but took it off because i wasnt sure if it was pushing too much pressure..