Tuning issue/help
 

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).
Posted via Mobile Device

Re: Tuning issue/help
 

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).
Posted via Mobile Device

Re: Tuning issue/help
 

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

LockDoc

Re: Tuning issue/help
 

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.

Re: Tuning issue/help
 

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.

Re: Tuning issue/help
 

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

Re: Tuning issue/help
 

Thanks! I’ll check and try these changes after work and see what happens. -Mike
Posted via Mobile Device

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
Posted via Mobile Device

Re: Tuning issue/help
 

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.