Carburetor Question (To Jet or to Go Up In CFM)

[Marshy]

So here's the thing... You'll never figure it out unless you troubleshoot. You always start with the easiest/most obvious things. Checking timing is a must IMO. Its also not the only thing to check but its the easiest so get that out of the way.

Your original questions were
1) do I need to rejet my Edelbrock?
2) should I move to a 650 CFM?
3) if theres anywhere else I should check for problems please let me know

The answers were;
1) possibly need a rejet although Edelbrock does not recommend the 600 cfm carb for an engine with cam duration over 220 @ 0.050" lift and you are running a cam with 243* duration. That in itself could make it difficult to resolve your initial problem. It was also pointed out that with a 1200 rpm idle you are now on the power circuit of the carb and the idle screws are no longer at play. That alone means you cent even begin to dial that cab in properly without getting initial timing and idle speed set properly.

2) Edelbrock actually recommends their 800 cmf carb given the large cam duration you have.

3) As we all keep saying, proper timing is the first step. Get the initial timing at about 10-12 degrees at 650-750 rpm then adjust the idle mix screws. If your ignition timing is too low then it will have a hard time idling and you will have to compensate by turn your idle speed screw (not mix screws) in more which opens the main butterfly to get your rpm up. This combined with the retard timing will also make it want to keep firing when you shut it off.

So, start with timing then move to the carb. Good luck.