While disassembling and following a rebuild guide I noticed that the APT(adjustable part throttle) device was not inside the fuel bowl. My carb has the bulge and cavity to house it but I don't know if it should be there or not. I decided on a rebuild because of a rich condition I couldn't pinpoint. Also concerned that the power piston spring is too stiff for my cam. Would any of these contribute to my rich mixture. ...One more thing, my rebuild guide showed both a front and rear power piston. Something is definately in the front bore , but it will not pull out like the rear piston did. It looks like a small shaft with a shape that resembles my idle mixture screw ends. It will twist, but not pull out. Sorry to throw so many questions together..any advice appreciated

 

Got a digital camera? Take some pics.
I'll see if I can find my old pictures tonight when I get home.

Aneroid cavity is not needed, if that's one of your questions.

You're right, if you've upgraded your cam and have less vacuum, you'll want a weaker power piston spring. You can buy a pack of 4 from Edelbrock. I used an old Q-jet body as a testing tool to figure out how much vacuum I have at idle, vs other conditions, then how much vacuum it takes to pull the piston down against all the springs I had. Then I picked the right spring.

- That's your "lean stop". I think it may also be called the adjustable part throttle, not sure on some of the terminology sometimes. You can loosen that until it comes out, but under high vacuum (idle, low load) your vacuum should pull the power piston down until it hits that lean stop. You should have the height set such that it pulls the power piston (and rods) into the jets just at the size of the stamped size - ie to the .043" part on a 43K rod. When there's no vacuum it'll always pop up to the same area, the .026" power tip. If you have the lean stop too far down it'll let the rod go into the jet 'till where it's .060" thick or so, and you'll be ultra lean. If it's too high then you'll always be on the power circuit - rich.

Set the height of that using a caliper, and the power piston and rods in hand. Get a set of power piston springs and try those. Get some pictures and MSpaint if you want some more help.
I'll see if I can find my pictures tonight, or do a search on here under my name on the carb board and look at any pictures i've posted before.

 

thanks a bunch, I think you have some good answers to what I'm lookin for. I understand the function of the lean stop now. On the powerpiston, does the plastic collar get pushed down into the bore on reassembly, and how far?
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Also I noticed that the carb had #72 primary jets installed. Is that too much for my 305 ? Motor has 180cc vortec heads and comp 268 cam with .454 lift.

 

Push it down until it stops, or until it's flush with the bore.
jets depend on air bleeds, it's hard for me to say what jets are right for you. Trial and error.
That should be a good running engine. Compression isn't too low with vortecs on a 305?

 

thanks again for the info.... I had the heads milled .040" so they should cc 60-58. Hope to get this carb back together this weekend. The problem I am having is from a cold start up. . I give it a full choke, setting the throttle blade closed. It starts , acts like it wants to run then dies. If I prop the blade open a bit and give it another pump then it starts, but runs rough till it begins to warm up. Also when warm and running there is no affect when adjusting any of the idle or throttle screws. So I'm thinking that fuel was seeping in from some source because I checked my plugs and they were sooty. Thats why I started a rebuild plus the fact I knew no history of the carb. Did not realize that there was only a handful of parts to this besides screws. Can't say I noticed anything cloged or leaking either. Any ideas on my start up problem?
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Forgot to mention, the choke break or pull off is working

 

Did you have the intake milled?

 

Good eyes 57.

After it's all put back together right (make sure lean stop is right, power piston arms are ABOVE gasket, etc. Then you can set your choke.

- Choke pulloff doesn't leak, holds indefinately?

If so, set it up as per spec. I think i've posted how to set your choke a handful of times, try to search and find it, I don't really want to type it out again.

 

no, did not, there was no angle milling on the heads. Just a straight mill. Everything appears to be sealing good. Used the thick felpro vortec intake gaskets. tightened all intake bolts to 12 ft.lbs.

 

I left the lean stop where it originally was. Decided to not take it out after the kit instructions warned against it. Was real careful to get the gasket under the power piston assembly too. My choke is electric and has one notch to seat into. It seems to close the blade adequately. Today it started better after I realized that my (+) battery cable was loose. Also put some pentrating oil to the choke levers and cams. The car motor was also stalling when I went to get the auto trans in gear. I finally figured out where the hard plastic vacuun line I never attached went to. The transmission I think. Cause now it will stay at idle in gear. Spark plugs are still very sooty. There is no black smoke out the pipes though . Do I need a road test before I check plugs?

 

one more thing..it's been he'll getting my fuel lines to seal at the carb. I'm using the factory line and fuel filter fitting too. Found a gasket for the filter holder in the kit. That helped, but the flared fitting has brought me near insanity. I used a freaking pipe wrench on it and there might still be slight seepage. It all sealed with little effort on my old cc q-jet!! Will get some pics up soon ...

 

Yea, make sure the little white gasket is on the end of the "nut" that goes into the carb to hold in the fuel filter. Then yea, you have to tighten the crap out of it or it'll seep

 

A straight mill of .040" is bound to require milling the intake.

You shouldn't have to tighten the crap out of the fuel line fittings. If a nice snug tightening doesn't seal it, you've got a problem with the sealing surfaces that should be addressed. Overtightening the fittings is a sure road to future expense.

 

The hard vacuum line I'm still uncertain, It ducks down the firewall some where. Thought it was my prob on stalling when it shifted to Drive. I richened up my idle mixture screws and that helped some what with the stalling. Drove my T/A for the first time yesyterday and it justs sucks. Ran better on the computer. After the drive I noticed my plugs had very clean insulators with blackened electrodes. Is it possible I have too much air flow for my jetting. Now my damm alternator might be bad. the voltage needle on my gauge goes crazy from 8 to 20 and back.

 

57, My q-jet had some crazy off-square bore and thread for the fuel filter housing. I bent my fuel line the best I could and had to use a rubber o-ring to make it seal properly. Would an intake leak cause clean looking plugs? What I don't understand is that the plugs were sooty when I was getting everything adjusted and after a test drive they are clean, but the electrodes are blackened
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yes, got that one to seal with the new gasket and heavy wrencing thanks

 

The gasket face mismatch between the heads and intake when the heads have been shaved but the intake hasn't can cause an air leak into the cylinders. You're likely to suck oil in as well, which would not lead to white plugs.

 

appreciate the replys...Took the carb apart again. I'm going to try some of the online Q-jet performance tips. What kills me is that in Park it revs like a superstock. Once it warms up that is. I was told to look at my ignition for the source, but I can't imagine the poor performance being there. I have a brand new Mallory hei dist. with an Accel Brute Force coil on top. I gapped autolite #103 platinums at .050". Should I pull a plug ,ground it and crank it over to do a visual or is that method useless? Also will the trans feel real slushy when the motor is no longer on the ecm or is that just from the lean engine condition?

 

ooh. Not sure about the accel or mallory parts, but aftermarket ignition parts can sometimes cause really strange ghost problems. First off, ditch the platinum plugs, those are for minivans. Then go back to a .040" gap.

Yes, you can pull a plug and crank it over for the visual. That'll only tell you if that plus is sparking. I really think your problem is more carb than ignition since you just rebuilt the carb.

What car is this? Year? Tranny? I'm not sure how auto trannys work with cc/non-cc carbs. I think you do need to fix the lockup part, but again, that depends on year.

If it runs well after it's warmed up, then it's the choke/choke system. Ignition and other carb problems don't disappear when warm - except for choke problems. (some rare exceptions.)

 

Sonix, Took another stab at the carb. Completely tore it apart again except for the needle and seat,checkball,retainer ,etc. Took a .090 drill and opened up the idle discharge ports, then I took a .078 drill and open up the primary jets to accomodate my .050 metering rods. Put the carb back together and on the car. Got an immediate start up this time, adjusted my idle mixture and curb idle. Took it out for a spin and finally felt some decent power. But I still have the alt/voltmeter going crazy and the dash/interior lights surging very brightly. thanks for your help

 

D'ah! Drilling jets is a big no no! But hey, I can't argue results eh? Sounds like it works, so power to you!

 

Most articles I read insisted the jets and rods have a .025 - .030 variance. for a mild cam so I thought why not. I drilled them out about .005. Other things, I'm gettin a spike in my voltage reading at the battery when my car is running only. Any ideas?

 

Yea, you'll want the jets that much bigger than the rods, but the jets have a special orifice taper on them, if you drill it you ruin it. That's just what i've read, thinking about it I don't really believe it to be true. (You have .030" of taper at a constant angle, you drill open another .005", the taper doesn't change...)
Anyway...

You probably have a voltage regulator going bad on your alt. Ie, the alt is dying. I'd just recommend a new alt. I highly recommend picking up a CS-144 (if you wanted my opinion).
I paid $50 for mine at a JY, and it took about 10 minutes to modify it, and the bracket for it to fit in my car. 130A now, with rock solid reliability. Do a search in the electronics board for my thread about that, if you're interested.

 

Kinda figured that on the alt. Just removed it and going to take it in for a check. Switching to a standard hei fom a comp.contolled hei had me concerned about the electric spikes. You and 57 been a big help on this one. hope to get this kinda feedback in the future, good day