Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Cant get new quadrajet to run
CamaroMan79:
First off this is an SMI stage 2 Quadrajet and Sean hasn't been much help with this issue hence why I am asking here.
First off my engine info:
383 stroker
9.8:1 compression
AFR 195 heads milled to 60cc
Comp Cams 282HR roller cam (.510/.520 lift)
1.75" headers
Edelbrock RPM Quadrajet intake
D.U.I street/strip dizzy
Timing at 16* initial with 22* mechanical for a total of 38*
Now on to the problem:
Ever since I have installed this Quadrajet the engine has absolutely no power. I hooked up a wideband 02 on the drivers side exhaust so I could adjust my AFR. Right now at idle I'm bouncing around between 13.5-14.7 so that's fairly close. In park at idle the engine seems to run and idle fine and I can rev it up fine. I have an adjustable regulator plumed in and I am getting 5-6psi at idle.
The problem is when I try to take the car (Camaro) out on the road and put the engine underload it has absolutely no power. I cant even spin the tires. As soon as I try to give it gas my AFR goes really lean up to almost 18:1. If I let off the gas and coast it comes back down to 13 or so.
The accelerator rod is already on the inside hole on the lever so its getting the biggest shot possible. This is the first quadrajet I have ever had and I have no clue what to do next.
I am running a mechanical Holley fuel pump and have an in-line billet filter with one of those small round mesh filters on the inside. After the in-line filter my AN hose comes up the side of the block to my regulator and then the regulator is plumbed onto the carb. The Quadrajet also has a paper filter in it behind the fuel inlet.
Not sure where to go form here.
CamaroMan79:
One other thing; I cannot get any vacuum reading from any of the ports at the carb base. I only get a vacuum reading form the rear port and the port for the charcoal canister. The pcv has vacuum because when I pull the hose the engine speeds up but I never hooked a gauge to that one. not sure if all this is normal or not on a modded quadrajet.
TommyK:
Can you give us a little history on the engine in question? Was this previously running well with a different carb? If so what kind?
How much have you actually driven it with the new carb? Have you pulled any plugs to see what they look like?
Have you put a vacuum gauge on it? Possible vacuum leak might explain the 18:1.
I am not familiar with the cam but I would try fattening up the idle mixture with the mixture screws and see what that does. It may need more fuel of idle than it is getting.
Shark Racer:
When you say "As soon as I try to give it gas it goes up to 18:1", do you mean, AS SOON AS, or with a bit of constant throttle angle higher than idle?
Very different questions.
"As soon as", means that you're not getting enough pump shot. Do you know what accelerator pump seal he used? How long ago was the rebuild? Have you verified that you're getting a very solid pump shot?
If it's with a steady throttle angle, then what you're looking at is a metering rod adjustment.
This of course assumes it's not a vacuum leak, as mentioned by Tommy.
Cliff Ruggles:
What is the carburetor number?.....Cliff
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