Idles High And Dies When Put In Drive.

I have just finished putting a new th350 in my 72 blazer. Ihave to set the idle high so when I put it in drive it wont die. It has this problem in all gears except park and neutral. Iam running about 10 degrees on my timing and have a Pertronixs HEI distributer. I have to double foot the brake and gas when the truck is put in gear at the stock setting of 8 degrees timing and the truck idling normal. Any suggestions ???:banghead:

Does the motor idle smooth now?
How long since the plugs, wires, distributor cap & rotor button were replaced?
Check your vacuum lines including the power brake booster.

Which carburetor are you using?

Does it have a stock camshaft? Does the exhaust have black smoke?

No it does not idle that smooth, it kind of ramps up and down. The plugs and wires are new. The distributer is new also. I am running an Edelbrock 600 cfm performer with a manual choke. The carb had to be cleaned out and I also replaced the floats and set them at 7/16 before putting all together. Some how the carb got filled with water while it sat in the carport the truck was in. I was thinking that it might be a plugged vacuum port on my carb for my vacuum advance, does that sound like it might be a problem? All the vacuum lines are new since it was a frame off rebuild. I beleive it has a stock cam and no it doesn't blow out black or blue smoke.

Find a port on the carburetor that keeps good vacuum and connect your vacuum advance to it.
Look down inside the carb while the motor is running, do you see gasoline dripping?

Ill give it a try and let you know.

I unhooked all my vacuum lines and blew them out along with my fuel mixture screws. Then I hooked my vacuum advance up to my lower vacuum on my carb. Started it up, did the timing and voilia it runs and shifts great. Thanks for the help Chris. Another place to look for any carb questions is on Edelbrocks site, they have video now to walk you step by step through it.
Once again thanks for the help Chris.

Glad you fixed it Jason. An air compressor is the best carb repair tool a shop can have...and a can of good carb spray. What you did also fixes about 80% of QJet trouble too,