nozzle drip again

[bsblguy]

1969 GTO 400/350 automatic. Idle tube is .038, idle down channel .046, upper air bleed .048, lower air bleed .068. idle air bleed screw is seated. Timing at 12 btdc. I do not have cam specs but it seems there is a mild cam in it, all else is stock. I put you kit in it with 72 jets, don't remember meter rod size. All was pretty good, idle a little rough in gear at 650, set it up some to be 650 with ac on. My accell hei dist. decided not to work so I put in a pertronix flame-thrower hei. Now my nozzle drip is back. Only thing changed was dist. Timing set at 12 btdc like it was. Don't know why this happened, doesn't make sense to me. What do I do to fix this?  7029268 carb.

[omaha]

   Well, normally to stop the nozzle drip you would add some bypass air BUT, to experiment a bit, you can pull a vacuum line temporarily to see if bypass air is what is needed. Pull a vacuum line (small one) and see if the rpms will increase without opening up the throttle plates. Jus pull the line and proceed to adjust the idle like normal with a vacuum gauge. If you can get the rpms to come up without the plates opening farther, then you know that you can close them up a bit and hopefully stop the nozzle drip. Then, basic math you can determine the size of the idle bypass if they are added to the carb. (from the size of the vac line that was pulled, internal diameter of the tube is measured). Do you mean to say that you actually have a carb with the screw on the idle airbleed passage, I have never seen one of those and would not even have the slightest idea how to adjust it. does it bypass air with it fully seated? Would like to see a pic of that. Good luck!

[Cliff Ruggles]

Not enough idle fuel to the mixture screws or not enough bypass air, or both.  I'd open up the down channel restrictions to .052" and open up the bypass air slightly and see if this helps?  Having an "unknown" cam makes giving advice difficult.  How much vacuum is the engine making at 700-750rpm's idling?....Cliff

[bsblguy]

Grabbed the wrong drill bit and opened up idle down channel to .059, upper air bleeds at .060. Set idle at 750 and vacuum is 13 inches. No more nozzle drip but have to set idle to about 980 to get 650 in drive and still a little rough idling in drive. Turning ac on in drive drops idle to about 580. I have a solenoid I can put on for ac idle speed. Do I need to close up the idle down channel some? It seems to be way to much drop from neutral to in gear.


omaha look at page 27 of Cliff's book and you can see the idle air bleed screw, that is the carb that I have. It does not like it opened at all.

[omaha]

vac advance in the ported source of the carb? This is what has come to mind because of the dist. change. Maybe the new vacuum can starts to work earlier (at a lower vac reading) this is what could be causing the drop in rpms. When the engine is in neutral, the can may be adding timing which could raise the rpm's and then when you put a load on it it slows the engine jus enough to put less vac at the dist. hence the timing retards and in turn the rpms drop off even more. The more load, more they drop. Usually this problem is more pronounced when there is low compression and way larger than stock camshaft is used. In this situation you need to be 100% sure your dizzy is in the "ported source."
If it is in there, disregard this advice. Depending on the cam (I have a feeling it is somewhat large) you will need bypass and more fuel so I think the booboo with the .059 idle channel restriction you may be able to get away with.
Good luck!

[bsblguy]

It is on ported vacuum. Timing set to 12, stays there with line connected or not and advances with slight movement of throttle.

[Shark Racer]

Are you setting your idle mixture and idle speed in drive or in neutral?

[bsblguy]

A little update. Changed the idle down channel to .055 (have an old carb laying around) and upper air bleeds to .048 and it is much better. Still get a slight nozzle drip but not constant, just a very small amount at times. idles at about 930, 650 in drive drops to about 560-570 when ac on. I've set mixture screws in park and in drive, didn't seem to matter. Idles rougher than I think it should. I compare it to my 455 TA 4 speed idle set at 800 and can put in gear let clutch out some with brake on so idle speed drops to 650 and it is smooth and that engine has more power than this one. Also compare it to my brothers firebird 400 and it is smooth in drive with ac on, ac barely drops rpm. I did let a little air in from a vacuum line and rpm did go up a little. do I need to increase upper air bleed some? It performs great, just this idle problem.

[omaha]

I would not mess with the airbleeds but would increase the bypass air slightly and maybe open up the idle needle ports a little (although I do not know what they are at now, maybe they are ok. Do you have full adjustability with the needles? If so leave them alone.) Still think that the thing could use just a tiny  bit more initial timing, maybe just shy of 15 btdc. The cam must be bigger than you think is what I am thinking. Argh, jus tear the motor apart and take a gander at the cam. (jus kiddin) although you could measure the lift at the valve with the valve cover off?? Hope you are using a vacuum gauge to set the idle, that is the best way to do it.

[Cliff Ruggles]

Checck the timing when the trans is placed in gear, to make sure it is rock solid, and not retarding a few degrees.  This would cause a greater drop in rpms when a load is placed on the engine....Cliff

[bsblguy]

Timing is retarding some when put in gear, what do I do to fix that? Over 40 years working on cars never had this issue before. There was a spring kit with the dist. Do I need to change springs?
I warmed it up , set idle at 700 in park, reset timing for 15 and it definitely liked that better. So right now set idle speed for 650 in drive, ac on, ac off goes to 710, in park goes to 1020. Timing changes a few degrees from drive to park. At least now it is stable in drive where I don't feel it may stall and before I did. Have not driven it yet.

[bsblguy]

Changed springs in dist. Now timing stays same from neutral to drive. RPM doesn't drop as much from neutral to drive or when ac turned on. Still have a little bit of a rough idle, not lope from cam. At least I can drive it again.

[68 Firebird]

Chased the same timing issue for a while before I realized what was really going on in my HEI.
I put some heavy factory HEI springs in and never looked back.  Timing now steady cold and hot.
Timing is now all in my 3400-3500 rpms and NO pinging, using ported source as it has best idle and
reduced rpm drop when placed into drive.  Also noticed the 13"Continetal Converter I am now using has less
rpm drop going to drive and better all around street manners.

Gerry

[bsblguy]

Added a little more bypass air and adjusted, now about as good as it's going to get. Can pull a vacuum line at idle and does not increase speed. Test drove and performs very well.
Thanks.

[omaha]

 Great! I think we all learned something from this one! I would have not thought of the dizzy springs being bad and causing fluctuation. I agree also that a looser convertor would help in certain situations.