carb jetting, quick!

[pishta]

I can get auto parts for cost at a local parts store going belly up. But not for long as stuff is going fast. I need a baseline jetting/Power valve recommendation for a 340 auto (2800) with a LD340 intake, equal length headers, stock 2.02 heads and a MP 284/.484 cam. I'm at sea level and got a Demon from a Drag Racer, still jetted for such. I also have a Carter 9636 that I run on it also.I have huge vacuum at idle, like 18 or so on the carter. The idle screws do nothing by the way. Thanks. No clue what I have in either yet, but I do have a strip kit for the Carter.

[pishta]

C'mon guys! Anyone run an 1850 or a 3310 Holley with a 284/484 cam? What are your jets like?

[hey-you]

Why don't buy a variety of assorted jets. That way you can test & tune your engine for different cam,manifold or even carb changes.
It always help to have a varety on hand.

[Jims451]

I'm not sure what it will take for jets.
Usually the big 284/0.484" cam (in a small block) kills vacuum and you need a lower value power valve like a 4.5" or a 5.5".
I think many of the 600 and 650 cfm Holley carbs come with 66 jet sizes. This may be close, but I can't be sure.
One of the best deals I got was to order the Mopar Performance Holley Jet pack, which has a huge selection of jets (in pairs), I think from 64? to 99 in one jet size increments.
If the shop has jets smaller than that for cheap, you may want to get them. I could use them if you can't, my mild 360 RV small block (that I sold to a friend) needs jets that are around 57 to 62 when running at 6,000 ft altitude.

If the idle screws have no effect, the throttle blades are probbably too far open and into the transition circuit of the carb, this is where the trick of drilling a small hole in the throttle blades will allow more air to pass when reducing the idle setting and restoring control of the idle circuit.

On a Carter/Edelbrock AFB carb your primary jet size and secondary jet size should be nearly the same, maybe 101 or 104? The primary can vary widely depending on the metering rod you use.
Like a power valve in a holley, you can get different step-up springs (from Edelbrock) to adjust at what vacuum the metering rods pop-up to enrich the metering.