2firebirdpals

New Carb- Rochchester----New Coil- new condenser- new Ignition Control Module- new coil grounding strap. Suddenly runs like crap overnight- Now I even get a -popping from the exhaust- Valves??? How can the valves be off- I never changed the timing- So Why the rough idle andf the intermittant pinging???? Codes show nothing wrong- standard 1-2.... Could new carb be running rich ?? But screws are set at factory and I just bolted in place. Whats up?? Vaaccum leak?? Dont think so--- It ran fine just a week ago.

88Camiroc

it the new carb bigger then the one before? How big is the one that you have on there now

2firebirdpals

Well the carb is an exact replacement of the Quadajet-- fully benched tested at plant and should "bolt in" with no fuss.
I was shocked to smell and see all that black smoke out of the exhaust and then when I heard that intermittant valve? popping- I decided to shut her off.
Sooooo I pulled off the New Carb and replaced it with my old one same model Quadijet. It ran better with the old one but it is a rough idle--- My brother and i went over the entire engine looking for missing connections or hoses and found Nothing. Where to look now??
Could the valve timing have changed?
Could I have a worn distributor??
This is driving me and my brother Nuts.

This car is a Replicar of the Ferrari 512 Testarossa- Its a shame that I cant chance taking it out to show the car to others . its a Trans Am with a Body Kit - Called a FireRossa. I took it out last week to a Car Show in Eisenhower park about 8 miles from my home. It ran fine going there. But when the show was over- I could not get the car to go over 10 mph- we had to limp home....... Fortunately- when I checked the Tranny fluid I was glad to find that the fluid was still pinkish with No Burning smell. So I still feel that the problem was loss of power because of an electrical problem. But now that I have changed a ton of electrical parts- its still running rough. And its throwing out NO CODES just-- 1-2....1-2.. over and over and over .Help

Chevy2035

What Year / Model? Motor? all that will help alot get this solved....... Sence none of that im just going to list a couple of things.

Swap coils back out, If you got some BWD or junk offbrand coil i have had them come from the factory defective.
The do the same with Ignition module.

I would pull plugs and look at them, Spark plug will tell you alot on how its running. Make sure you didnt cross any of your wires. If its an LT1 opti-spark they are easy to get a wire crossed.


Do you have a Catalytic Converter?
If so unbolt your y-pipe and see if it runs any better, Its possible your floats are misadjusted and it dumped a ton of gas in your motor overnight, Just once is all it takes on newer type honeycomb converters will ignite that gas inside and melt the honeycomb. The steel wound pretty much can survive anything if you know how to clean them.

88Camiroc

I would have to agree with him. It sounds like you are running extremely rich. I would again check for the connectors and i would adjust the mixture screws and see if that changes anything. If it does and it gets better but not a 100% better then you need to down size your jets or adjust your floats.

2firebirdpals

Thanks to all----- Its a 1984 Trans Am 700r4 305-- the old carb seemed to be running rich soooooo I bought a rebuilt from National Carbs in Georgia- its the same model Rodchester Quadijet. The carb comes flow tested and PRE set at plant. I bought other carbs for my brothers Mustang and Chrysler and all of their carbs come Pre Set at Plant and all worked OK.. But This car always ran rich --that is why I switched out carbs. In fact- I can tell that there must be some gas dumping - even in the old carb- because my oil dip stick shows that my oil level above by a 1/2 inch. That my friends is due to gas washing down into the crankcase. For this very reason-- This is why I bought a Rebuilt Carb PreSet at plant in order to make certain that I won't end up dumping gas into the crankcase....
Could it be that this New Carb is "Not" properly adjusted?? Or adjusted waaay too rich from the plant??? If soooo how do I go about leaning the carb mixture. So Do I turn them "IN" clockwise? thanks

88Camiroc

yes you would adjust them in and listen for the engines to smooth out. one way to tell if there is gas in the oil is to pull the dipstick and stick a lighter to the oil and see if it catches fire if so then the gas is over flowing the carb.

sweetmelissa

smell the dipstick

2firebirdpals

Went to autobarn and bought a tool to properly adjust the carb screws.
The old carb was set waaay too rich - I leaned it IN and it IDLES better But I need to know HOW many turns before full seating for each.
Right Now I have the passenger side screw 3 full turns from fully seated and the Driver side screw 2 full turns from fully seated. I ran the engine 10 minutes but it still seems "uneven and off". I will check a few spark plugs when the car cools and see if its too lean Or too rich.

Also when it gets dark I will check for "arcing" from the distributor cap/Coil area. I think I'm on the right track---- hope so.

What is the prescribed # of Turns required to properly adjust the 2 carb idle mixture screws. I set them out from fully based 3 and 2 turns respectively.

2firebirdpals

OK-- just came back in from outside---- No ARCing from the coil,plug wires or Distributor---easy to tell in the dark ----- the #1 plug looks fine- no black soot deposits-----The car had a bit of a hard time starting-- probably because the Idle screws are too Lean--- but I'm prepared for that---- I'll just turn em out a little on each side -counter clockwise to make em a bit richer. But For Sure - NoWay am I gonna turn em out any "More" than I have to. This Carb was set waaay too rich for waay too long For me to ever wanna go back to Over Rich.

Chevy2035

That info helps narrow this down a bit.


First off. 2 full turns out from seated is where i always start on pretty much any carb.

Second, If you have a Catalytic converter, Unbolt both sides of your Y-Pipe. start and see if it makes any difference. A Clogged catalytic converter will cause it to act like that.

Third. Gas getting into your oil is horrible for an engine, Even a few minutes of running with gas in your oil can do some major damage to rings / cylinder walls. check your compression.

Check your fuel pressure also, Having to high fuel pressure will cause it to run rich and dump fuel into the motor.

I had a 305 that ran ruff real bad. Was orignally a crossfire injection and someone left the orignal 14psi fuel pump in and converted it to carb. I got it for 350$ and put a 50$ regulator on it and drove it for a few months and sold it for 1700$


And final. Future reference type of thing.
The look, Smell and deposits on a spark plug tell a story, just looking dose nothing, Just smelling dose nothing but both together.

The type of plug makes a huge difference. Never use Bosch junk (Especially the dual and quad tip ones, they took that from European cars like lambos that have huge coils on each plug 500k volts or some crazy ****. Normal old copper cores require 5-10k, New coil on plug iridium are around 25-65kvolts). AC Delco, NGK, Autolites are about the only plugs ill use.

88Camiroc

well its not healthy for your engine to run rich. It shortens your plug life your cat life and causes a **** load of carbon build inside the engine to the point it can gunk up around your valves. If that happens then it will cause them to not seat all the way can back fire and lose of power.