Not quite right at idle

[gtome]

Ok, so I got the carb on. Actually fired right up with little drama. But something just isnt right. It starts right up, and will idle. Revvs great it seems. I have the choke hooked up and it seems pretty good at idle until the choke pulls off. Then its a little irradic, but will still idle. I tried the tip in procedure, and it smooths out a little with the choke flap just slightly closed, but much more than that and it wants to die. Also, when its warm and the choke is pulled off, im getting some popping. I noticed also that the air/fuel screws dont seem to do a lot. They make slight changes, but I can screw it all the way in and it doesnt really slow it down a lot. And I assumed when it was screwed in as far as it felt like it would go, the springs would be completely compressed, but they arent. Just a side note, I lost the paperwork I made for it and didnt know hoe far to turn the APT screw out, so I took another one I had apart and it was 4 turns out. So thats where I set it. Always sounds and feels good when revving. Where do I go from here?

[Cliff Ruggles]

Carburetor number, engine specs, and what has already been done to it?.....Cliff

[gtome]

Well this will be tough because I lost the paper I wrote everything on for the carb.
Engine is a Poncho 455 +.30, 9.3:1, 60919, 1.65 rockers, V-Max lifters, RPM intake, headers, HEI.
Carb: 17057274, recipe #3 from your book, 74 mains, Metering rod - upper step is .44 and .26 tip, .110 idle bypass air, electric choke. Vac advance is hooked to the back tree full manny vac.
Timing is at 30*

Thinking about it more....since im getting a popping at idle, do you suppose I could have a vacuum leak? I dont know where it would be coming from, but I suppose that could cause popping/backfireing.

[Cliff Ruggles]

"Popping" at idle could be many things.  Plug wire, spark plug, vacuum leak, incorrectly adjusted valve, lobe gone off the cam, etc.

That is the same carburetor I use on my 455 engine, excellent unit.  Your engine is a tad low on compression for that cam, so it's going to want a lot of idle fuel and idle bypass air, but with the Rhoad's lifters it should be fine.

Which metering rods, "K", "P", "L", etc or did we supply them?

I don't use or recommend that much timing at idle, as that will also induce a "skip" or miss in the engine.  I used to run the same cam in a 455 and it idled fine with 10 degrees timing and ported to the advance.  It didn't really like manifold vacuum to the advance, sort of "skipped" and missed a bit more when I tried to tune it that way.....Cliff

[gtome]

Plugs, wires, dist, cam, and lifters are all new so they should be good. Idle bypass is at .110". Metering rods are ones you sent me. I will try backing the timing off too because I always have had trouble with hot start problems anyway( something I notice now seems to have gone away!). I also am running full manny vac, but I will be happy to try ported. I tried ported on the Holley, but I could actually feel it come in and I didnt like it. And it smoothed out the idle on it. My engine has also been a little shakey at idle. No clue why?

I am happy to report that I was getting 12-13 hg of vac with the Holley and 15-16 now with the q-jet.

[gtome]

Im running the light blue spring too by the way.

[Cliff Ruggles]

It might just need more idle fuel.  If it smooths out any at all when you tip in the choke flap, after adjusting it to the highest vacuum with the mixture screws, it wants more idle fuel....Cliff

[gtome]

Im going to try it again tonight. But turning the mixture screws didnt really seem to affect the vac. Of course it does slow the idle down when you turn them in.
It seems to smooth out the idle when I tip the choke flap in, but if I cover the hole at all with a finger or 2 it wants to die.

Also I started it last night. And when I looked at the carb, there was fuel coming out the accel pump rod hole, and when I revved it, it was shooting out the vent. Turned it off, then restarted it and it was fine. Would that be a momentarily stuck/clogged needle and seat?

I unhooked the vac advance and plugged it and that does seem like the car liked it better. My hose was too large to fit snug on the ported vac port, so I will grab some smaller hose tonight.