I have a 1970 340 six-pack in my 73 Challenger. The engine was completely rebuilt, port and polished and blueprinted. It has Dynomax headers and a 284 (advertised) duration cam with .480 lift. The problem is that the engine will not idle below 1100 RPM and there seems to be a serious lag in the engine just before the other 4 barrels open. I am running the orange box and Bosch Planinum plugs and the timing is advanced about 12 degrees advanced (seems to idle better there).

I think there must be a problem with the carbs or at least the center one and can find no technical information as to how adjust them. Some people told me that they thought the carbs need to be re-jetted and someone else told me that there is something wrong with the secondaries......but before I start monkeying around with them (probably a good winter project), I was hoping to find a place to do some research on them. If anyone has any ideas or web addresses, it would be greatly appreciated.

Thanks!

Brian

 

I would try Holley carbs website. I think I saw something on the set-up there. The lag may be a linkage problem, or accelerator pump set-up issues. Is it popping or anything like that through the carbs. The idle problem sounds like it may be way to rich at idle.

Have you done the break-in on the cam already?

 

http://www.holley.com/HiOctn/TechSer.../Instruct.html

Here's a basic rebuild and adjustment link for the 2300 series carbs.

 

Thanks for the info. Yes, I did properly break in the cam (high idle for 30 minutes). It did backfire through the carbs until I advanced the timing. When I first started it it was retarded by about 5 degrees but I had to advance it to keep it at idle.

 

Are the blades closed on all the carbs at idle? If not, adjust the idle screws out until the blades are closed. Run the idle mixture screws in and bottom them out, then back them out .5 - .75 turns and start car and see if it idles better.

 

I'll check into looking for the adjustments......these are a bitch to adjust since they're so close together.

 

I remember reading about that when I was putting my 360 together.

 

Thanks for the info....turns out that the center carb was in need of a rebuild. It sat on a shelf for over 10 years. Turns out that all the gaskets have rotted out and there was fuel dripping directly into the intake. Definately explains alot!

 

Hows she runnin now?