Tuning issue/help

[mm1077]

Hoping someone here can help : ).
I’m so close to being able to actually drive my truck daily…I just upgraded some parts and did basic tune up. I can’t get my idle mix screws to have any effect on vacuum reading and I can turn them all the way in (gently) with no effect on anything.

Vacuum advance is unhooked from ported vacuum source and capped, all of my vacuum hoses are new, I put the plug in the back of the carb, sprayed liberally with brake cleaner looking for vacuum leak/idle change, timing showing 17 degrees at idle- motor has a cam but I don’t know the specs. The mark, however , did sort of ‘move around between about 15-17. I think I’m using the timing light right lol…turned it up to 17 to show the mark at 0 on the tab. I Hooked up the electric choke and set it so the butterfly is just slightly open when cold . I also had installed a vacuum canister to hopefully help with the brakes (line from intake to canister and then from canister to booster).
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[mm1077]

Carburetor is new Edelbrock AVS2 650, Ignition is MSD 8362 that was in the truck when I got it- I replaced cap, rotor , new 8.5 Msd wires, plugs, fuel pressure regulator (set at 5psi).
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[LockDoc]

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Not too good at figuring out tuning issues but I know how to rotate a picture....

LockDoc

[68 P.O.S.]

If the idle mixture screws have no effect, you're gonna have to open the carb up and see what's blocking or restricting the flow. The transition slots are probably overexposed.

[geezer#99]

Plug the distributor vac pot into manifold vac port and the idle should increase. Then turn the idle back down and see if the mix screws work.

[72SB]

IDK if the Eddy AS is the same as their regular carbs but the book that came with my 600cfm Eddy says 1 1/2 turn as a starting point. +/- 1/4 turn is all you should have to do when dialing it in. Turning mix screws should absolutely change idle and vac reading. ALWAYS use manifold vac port for vacuum advance

[mm1077]

Thanks! I’ll check and try these changes after work and see what happens. -Mike
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[mm1077]

Originally Posted by geezer#99

Plug the distributor vac pot into manifold vac port and the idle should increase. Then turn the idle back down and see if the mix screws work.

I switched over to manifold vacuum port and everything started to come together! I was able to adjust to about 13-14hg vacuum by adjusting the mixture screws slightly and they were responsive. I set idle screw to about 950 and it idles about 750ish in gear. Thank you very much for your help
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[garyd1961]

Before you take anything apart try taking the idle screws out and spraying some carb cleaner in the screw holes. I have had this to work in the past.