Car won't run in Az......

[azfordman]

Originally Posted by blykins

Does it stumble right off of idle? How do you have your idle set? All on the primary side? Or do you have a little bit of the secondaries opened up too?

The carb only has idle adjustment screws on the primary side. Secondary throttle plate is closed 100% at idle. Took the primary screws in all the way, backed each one out 1/2 turn and hooked up a vacuum gauge. Increased the idle screws until I achieved maximum vacuum, then backed each one in a hair to drop it 1 hg of vacuum....kinda tough because the vacuum is not steady....the needled bounces and fluctuates around 1-2 hg, but is strong around 21 hg. The car idles fine...just a bit of a lope to it. There does not seem to be any miss at idle....only when cruising with minimum throttle, if I down shift and kick the RMP's up the stumble/miss goes away.

[blykins]

Originally Posted by azfordman

The carb only has idle adjustment screws on the primary side. Secondary throttle plate is closed 100% at idle. Took the primary screws in all the way, backed each one out 1/2 turn and hooked up a vacuum gauge. Increased the idle screws until I achieved maximum vacuum, then backed each one in a hair to drop it 1 hg of vacuum....kinda tough because the vacuum is not steady....the needled bounces and fluctuates around 1-2 hg, but is strong around 21 hg. The car idles fine...just a bit of a lope to it. There does not seem to be any miss at idle....only when cruising with minimum throttle, if I down shift and kick the RMP's up the stumble/miss goes away.

What kind of carb is it? You may be into the transition circuit on the primary side, which will cause a stumble when you're in between the idle circuit and the jets.

As for timing, you need to choose a little more "scientific" way of waiting until it pings then backing it off.

I'd set the initial anywhere from 12-16 degrees and check the curve at full advance. 34-36 degrees total should be fine. Check to see where the total advance comes in. Lighter cars will stand a quicker timing curve. I like my Cobra engines to hit total advance around 2200-2400 rpm.

[azfordman]

Originally Posted by blykins

What kind of carb is it? You may be into the transition circuit on the primary side, which will cause a stumble when you're in between the idle circuit and the jets.

The carb is a Holley 600 I believe, #80457-1, took it off of my 84 Bronco that has a 351w as well. If you read this entire mess of a post, the carb that was on the car, a Motorcraft by Holley #50264 would vapor lock after 10-15 minutes of driving in the heat. Putting the Bronco carb on the car solved that problem. I will have to pick up some jets in the next few days, since I am sure that the home drilled jets will not be ideal. Between the larger jets and the timing I think I may be in good shape. I still may want to put a better carb on the car....not sure if a Holley that was on a full size Bronco is the best application for a car like a Cobra....what do you think Brent?