Help with idle rpm and carb on 340

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1972orangebeast

1972orangebeast

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Ok so I have finally got my dart back on the road as now I'm down to tuning carb, idle, etc. the problem I have right now is with my street avenger 670 carb, electric choke , vacuum secondaries, it will not idle at all when it's cold and when warm won't idle any lower than 1000 rpm.

Details
-manual car
- motor is 340, .030 over, rpm air gap intake , x heads, comp springs , comp nostalgia cam lift .484/.484 duration 284/291,timing is set at 30 deg, Doug's headers.
- vacuum is pulling at 1000 rpm around 13-14 lbs
-I've up the jets to 70/72 and power valve was 6.5 and changed to 5.5. (Either one idle was same)
-electronic set up orange box and distributor has no vacuum advance was rebuilt and lighter springs

I did slap on my buddies elderbrock performer 750, just rebuilt it back to stock , seem to idle better cold but it would not idle under 1300 rpm

Seems to run pretty good once it's warm but still little hesitation and the plugs are still on the lean side, when I jet up next step the plugs go black!!
 
See if the cable is hung up, disconect and check it out!
See if it idles better then. I have an airgap and had this issue.


1972orangebeast said:
Ok so I have finally got my dart back on the road as now I'm down to tuning carb, idle, etc. the problem I have right now is with my street avenger 670 carb, electric choke , vacuum secondaries, it will not idle at all when it's cold and when warm won't idle any lower than 1000 rpm.

Details
-manual car
- motor is 340, .030 over, rpm air gap intake , x heads, comp springs , comp nostalgia cam lift .484/.484 duration 284/291,timing is set at 30 deg, Doug's headers.
- vacuum is pulling at 1000 rpm around 13-14 lbs
-I've up the jets to 70/72 and power valve was 6.5 and changed to 5.5. (Either one idle was same)
-electronic set up orange box and distributor has no vacuum advance was rebuilt and lighter springs

I did slap on my buddies elderbrock performer 750, just rebuilt it back to stock , seem to idle better cold but it would not idle under 1300 rpm

Seems to run pretty good once it's warm but still little hesitation and the plugs are still on the lean side, when I jet up next step the plugs go black!!
Click to expand...
 
Set your initial to around 14deg to start with. Then find what rpm your engine likes to idle at,and set your curb idle screw there. Probobly around 800-900 rpm if all else is ok (in neutral,not in gear). With your Holley have your idle mixture screws at around 1.5 turns out to start with,then slowly turn in both screws until you see the rpm start to drop. Slowly then start turning the idle mixture screws back out until you achive the highest rpm with the mixture screws only.You will probably end up between 1.25 and 2 turns. Then back down your curb idle screw to the rpm you determined the best idle at. There is more accurate ways of doing it,but this will get you very close if done properly. Hope this helps!
 
Ok I understand initial timing, I have a digital toming light, at idle it says I'm 34 deg, I rev it up to 3500 and still stays at 34 deg. My light I is digital so I dial in untill marks at zero, when I do this it says 34 idle or higher doesnt matter. Now if I pull the trigger (which is supposed to make it like an old gun) my marks are jumping all over the place. What now?
 
Sounds like something hangin up in the dizzy maybe springs are too light.
 
You are correct! I got it figured out last couple days of drivable weather. Still need to adjust the new dizzy, I got a Jegs distributor. It's not advancing enough right now, but they say it's fully adjustable. I haven't had enough time to pull it and adjust it.
 
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