Hey guys,

I recently bought an 89 GTA with rebuilt 355 and a holley 670 carb. It was running pretty poorly, so I decided that 40 bucks and a rebuild kit would be a good place to start. I overestimated my handiness. I rebuilt the carb, but kinda ruined one of the jets. I put it back in, but not exactly straight and I stripped the hole it goes into. Now my car won't idle. So assuming I messed something up with the carb, I need to replace it.I rebuilt it because it stalled, was hesitant to start, and most importantly, I was getting about 3 miles to the gallon. I have a veritable slew of questions about it.

-The car ran before the rebuild, but could my "not idling" problem be anything else?

-Which carb should I replace it with? I don't need a whole lot of performance, actually fuel efficiency is king here.

-My idle mixture screws don't seem to do much, probably a fault in the rebuild, right?

-The car idled somewhat yesterday, but stalled frequently. It is colder today. Still probably a carb problem?

If there is any information I left out, I'll do my best to add it. I don't know too much about the car, being that I bought it a week ago, but still, I'll find out what I can. Any help is appreciated guys. Thanks so much.

 

Idle mixture screws don't do much anyway - big misconception as to what they really do.

If you screwed up the threaded port for the jet, not sure if anything can be done there. Miught try to use a tap and rechase the threads straight, but you're kinda screwed there.

No carb is going to be better or worse for mileage, so any choice is fine - you need 650 - 750 cfm. Might as well replace with the same Holley, since all thye correct bracketry is already in place.

How was fuel delivery accomplished? Did they use the intank pump? What fuel pressure regulator? What's the fuel pressure? What's timing set at?

Is it an automatic? If so .... Did they use a TV cable geomtery corrector? Is there a method to locking the torque converter?

 

Thanks for the quick reply,

The intank pump was used, the fuel pressure was between 6 and 7. They did use a tv cable geometry corrector.

I'm not sure what the timing is set at. I don't have a timing light, and money is kind of tight because I have to replace the carb. Is it worth investing in one? I'm also unsure of the fuel pressure regulator. I also have no idea if there is any system to locking the torque converter.

Sorry there are so many unknowns. If any background information helps, I was smelling serious fuel, my car was stalling, idling rough, and being extremely temperamental as to when it started, all prior to the rebuild. When it ran yesterday, it was idling even rougher, and stalling even more frequently.

Thanks again for the help.

 

the idle screws set the idle up to be smooth. you can raplace just the new metering block for the one you damaged. then try and set it up from there. remember there is an idle circuit, an acceleration circuit, and secondaries.

 

Well would a slightly crooked jet make the entire carb inoperable? Is it possible that the carb is just miserably out of tune?

 

The crooked jet will mess up the carb...but it shouldn't affect the idle. It sounds like your timing is WAY retarded. This is causing you to open the throttle blades way too far to get it to idle. The consequence of that is it is uncovering the transition slots way too much and dumping in a lot of fuel. Another clue is that the idle screws do nothing. If the carb is set up properly, turning any one screw in all the way should make the engine stall (or nearly stall).

Borrow a timing light and set the base timing. I don't know anything about the engine or your distributor, so I am hesitant to tell you what your base timing should be. After you set the timing, see if you can close up the throttle blades and get it to idle. A vacuum gauge would be a good investment too.

 

My mistake, the idle screws when turned all the way in will cause the engine to stall. What I meant was that any adjustment to them was not smoothing out the idle whatsoever. I will try to get my hands on a timing light, and see if that helps. Sorry for the newbie questions, but would poor timing amplify any problem with the carb? The thing that keeps me scratching my head is that it ran, albeit poorly, before the rebuild.

 

6-7 psi fuel pressure is too high, you need 5.5 psi max, usually 5 is better.

Don't know where you are located, but Harbor Freight has timing lights as low as $15. Timing means the world. It doesn't have anything to do with the carb really, but if the carb is feeding too much or too little fuel for the current timing, then the car will run poorly.

Since you've been told that the metering block can be changed without buying an entire new carb, I'd get a new metering block for that jet, then that's one issue you don't have to worry about.

Really need to find the fuel pressure regulator and find out what type it is - if it's not a return-style regulator then you'll have problems with fuel pressure, as regular old dead-head type regulators won't work with the intank fuel pump.

 

Well I guess I way overestimated the price of timing lights. I can pick one up today. I also think I'm going to just replace the entire carb, because this one has been nothing but trouble, and I'd like a fresh start. I did some shopping and I can afford an edelbrock 1406 or 1407. Are those good carbs? I'm sure that question couldn't be more ambiguous, but I really have no idea, haha. As for the fuel pressure regulator, I checked it out and it seems to be similar (if not the same model) to this http://www.holley.com/12-803BP.asp

As an update, when I turn the car on now, it will fire up, but will not even come close to idling. I'm also beginning to smell something (I'm not sure what) burning, and I have noticed a wispy white smoke coming from the exhaust. Sorry for my ignorance, but I'm new to this whole "carburetor" deal....and the whole "thirdgen" thing.....and that silly "automotive repair" idea. As always, any help is appreciated, thanks for everything so far guys.

 

That fpr will be fine if it's like the link you posted and it's a "bypass" or "return" style.

Many folks don't like the Edelbrocks for whatever reasons, I have no issue with my 1406. Runs fine right out of the box.

 

I wouldnt replace the whole carb. That is a damn good carb and far better than a eddy carb. I will admit a little bit of head ach tuning easy but takes some playing around with but a good carb. I would replace metering block then sort out timing issues. Remember timing first "if the timing is not correct tuning carb will do no good" start with timing once thats dead on adjust float level via needle and seat then hook vac gauge and adjust mixture screws and idle then look at power valve to make sure thats correct then you will be good to go my friend. I wouldnt put a eddy carb on my lawn mower! If you wanna go fast HOLLEY or Quadrajet but only a quad if you have someone that knows them in and out. My drag car ran its best et with a awesome quad but I luckly had someone that knew how to tweak them better than anything else. Good luck my friend. And gentleman dont take it wrong. Eddy carbs are fine for normal app but if you want all out power and performance you just cant beat a Holley type carb. I run a 750 dbl pumper on my 355 and she screams clean to 7200 rpms no problem.