I am new to AVS carbs and am wondering about tuning, I have a stock 440 auto AVS carb, its bolted on my 440 with ported 915 heads, TRW six pack pistons, .488 108 CL purple cam. it has a cast iron intake, and HP manifolds, broke the cam in on the run stand today, and the engine runs good. I know this is a very broad question, but do you think the engine will run good with the stock jetting? or will I need to jet it up? it idled nice and responded to the idle mixture screws. just wondering if I should leave it be till I get it in the car and drive it, or if it will need some jet? I know its a hard question to ask by sitting behind a keyboard, I just didnt know if these carbs are good in stock form when you upgrade the engine

Thanks

Duane

What intake is on the motor?
Do you know the true mechanical compression ratio ?
If your running the stock cast iron intake did you block off the cross over heat passage in the block or heads?
Let us know those answers
BTW, I am not a fan of Mopar brand purple shaft cams

Do you mean the MP .484 cam ?? I just have not heard of a MP .488 cam but I may be wrong myself and just not up to date on them. Myself I used the MP cams a good bit over the years and I found I liked them all in my combo's but like any combo you just have to get the full combo right. Many stick a .484 cam in a stock 383 with 3.23 gears and a stock converter and then say the cam is no good. Yea right its the cam. But anyway in a basic reply if the eng is modded some and it used the AVS on it in stock condition then it will most likey need some jet change. Best bet in todays world is put an 02 sensor setup on it and then you see just what it needs. I came up doing it the old school way in the 70's to determine jetting but in todays world its best to take advantage of the technology we have and install the 02 sensor setup. Then you can jet for good performance and mileage. Ron

How does the car run right now when you lay into it ?

My mistake, its a MP .484 108 centerline cam, the original 69 intake which was also ported to match the heads, the heat riser is blocked off, and yes, heads were cc'd, and compression is 10.4 to 1. this engine is going in my 69 charger, it will have a 2800 stahl hughes converter and 3.55 gears with a 26" tire. Yes, I can put O2 bungs in the exhaust, but its not in the car yet, and havent bought an exhaust yet, so I was looking to see if the stock jetting will get me in the ballpark.

Thanks

Duane

Be very,very careful on the jetting, timing and spark plug heat range with that compression ratio on pump fuel
Look at the spark plugs a lot, especially #7
Good luck, keep us in the loop as you go forward

Thanks, I am actually breaking the engine in on the run stand with Sunoco 110 purple, but I see myself running a Purple/Ultra mix all the time. I know the compression is a tad high, its one of the reasons I went with the cam I did, to kill some cylinder pressure with the overlap. when the block ended up having a .010 deck clearance, I put a .060 cometic in it. just wasn't sure if I should jet it up from stock right from the start a bit.

Put a O2 sensor on it.. it will tell you if
you need more jet

All OE ('68-mid '71) AVS's are lean due to the discombobulated gov't emission regs of the era that Ma & everyone else was striving to keep up with. How lean I ain't sure but I put an earlier AFB on a '68 440 GTX
(OE AVS) & it woke it up. AVS 3 step rods/long pri jets strip kits are as rare as hens' teeth but you can easily sub in Eddy shorter primary jets/2 step rods so you have some adjustability and a .001" change on a jet makes a far greater change than .001 on the rod. I would just get some jet/rod combos in there several tho or so richer than what is in there now. All that is needed is to make the domed metering rod caps flat. fill em with JB weld & cover em with scotch tape & invert em on your bench so the mud will settle flat then let it set up for several days. JB says 24 hrs & I like to give it more especially on a thick app of it. EDIT with more thought, the emissions off calibration of the AVS's is more than just the rod/jet AF ratio. Just me I might swap in the eddy items for a quick start or maybe even polish the rods down a few thousandths (say on the cruise and power sections & use the middle transition step to help you keep the (2) diameters seperate. People drill jets which from my exp with drill bits is highly likely way less accurate. I'd leave em be. some very fine sandpaper/solvent/smooth steady twirl & keep checking with your mike. You have a reasonably healthy build & I would look toward a much better carb, one of the modern ones that all of the systems are adjustable. #1 as Mr P body said get the LM2 meter plumbed in & see where you are at.

Overlap does not kill cylinder pressure.

What do you have for piston to head clearance?
What do you have for cranking cylinder pressure?

I'm thinking you would be happier with the .528... I know you don't want to hear that now

It might help to know which 440 AVS you have. The A-120 low performance AVS had the smaller primaries like the 340 and 383 AVS carbs. The A-134 HP 440s had the 750cfm AVS carbs with the big primaries. I see a lot of the 4966S AVS carbs at the swap meets. Basically the same carb as my 340 AVS (4911S).