Carb Tuning question

Carb is an Edelbrock 650 Thunder with Electric Choke

Engine is my 354 Hemi in the 52 Dodge Truck (build post in the link in my signature line).

Engine starts right up, but it will stall out if I don't give it tap on the pedal. Once I give it one or two taps, it will stay running fine (I don't have to keep pedaling it to keep it running).

After cold startup, it runs a bit rough, but smooths out when it warms up.

After it warms up, it idles good in park, but when I put the truck in drive or reverse, the idle speed drops and it idles rough. Idles rough when I'm at a stop light too...but smooths out if I put it in Neutral or Park.

With no load, it idles around 900rpm
It drops to around 600-700 when the engine has load on it.


The idle screws are about 1 1/2 turns out each.

Timing is around somewhere in the 8-12 range (need to get a timing light with a dial on it...the balancer only has a TDC mark, no numbers.


Where do I start with tuning to get it running better?

 

Sounds like the electric choke needs adjusting maybe a couple of notches too rich.
Also check for vacuum leaks.

 

I would try and get the timing right before tuning the carb. With no marks, advance it till it pings at full throttle in top gear and back it off till it stops pinging.
Change the idle mix screws together at the same time 1/4 turn until you get the smoothest idle. Probably richer for smooth idle, but try both directions. You may have to compromise between a smooth idle in gear and a too fast idle in neutral if the cam is real lopey.​

 

Tune the idle mixture screws with a vacuum gauge and go for the highest reading on the gauge... Start with 1 full turn out from the seats..

 

mine was doing the exact same thing. it was a vacuum leak from my PCV. looks cleaner without it anyway

 

Compromise, it needs to idle good in gear at operating temp. Bit higher rpm in gear & that will give you a higher rpm in park too.
The cold throttle tap may be a fast idle cam adjustment/sticky for when its on the choke. And the rough idle when cold may be a choke adjustment.