Dirty ports
Thread Starter
Racer
Joined: May 2006
Posts: 264
Likes: 0
From: Fort Myers, Fl / St. Paul, Mn
Dirty ports
I just changed from an Edelbrock single plane intake with a Holley carb to an Edelbrock Performer with a Quadrajet (SB 350). Much better low end and throttle response. Feels like a different car.
When I had the intake off I noticed that the intake ports in the heads were black. It surprised me because I would have thought they would be very clean. What would cause this? Should I be concerned?
When I had the intake off I noticed that the intake ports in the heads were black. It surprised me because I would have thought they would be very clean. What would cause this? Should I be concerned?
Burning Brakes
Joined: Apr 2007
Posts: 1,028
Likes: 1
From: SOUTH ELGIN IL
Were you dumping fuel in there with a 750 or larger double pumper and a single plane intake? I was doing that for awhile on a previous car w/ a 750 and a Weiand Xcellerator and noticed the same condition on the intake ports.
Thread Starter
Racer
Joined: May 2006
Posts: 264
Likes: 0
From: Fort Myers, Fl / St. Paul, Mn
When I bought the car 2 years ago it had a Holley 750 DP on it but it had a bad power valve. It oozed gas even when idling. I put a more reasonable sized Holley SA 570 but in spit of the fact that it was a pretty stingy sized carb it always had an unburned fuel smell to it. I hope this Q-jet is the answer. I'd sure hate to think that it may be a ring problem.
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Instructor
Joined: Dec 2004
Posts: 113
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From: Fullerton CA
You may have considerable carbonization in your combustion chambers if it was running rich for long. You might want to pick up some "Sea Foam" from your local auto parts. Bring it in through the vacuum into the intake (follow instructions). It works very well. You may notice a difference in performance because carbon build up can really screw up the thermal dynamics of the motor.
Thread Starter
Racer
Joined: May 2006
Posts: 264
Likes: 0
From: Fort Myers, Fl / St. Paul, Mn
Makes me giddy 
just thinking that I may have a lopey cam . . . . but I don't think so.
I have run, with the SA570, the mixture so lean that I get real bad low speed surging and yet it would still idle well.
I just went out and looked inside the old manifold and it has a damp oily coating. The area under the carb is comparatively clean. The worst of it is at the bottom of the runners, including the tops (roofs) of those runners. I also swabbed the inside of the PCV vacuum line and found very little there. If this was coming from a rich carb wouldn't there be residue everywhere?
Is it possible this is a valve problem?
just thinking that I may have a lopey cam . . . . but I don't think so.I have run, with the SA570, the mixture so lean that I get real bad low speed surging and yet it would still idle well.
I just went out and looked inside the old manifold and it has a damp oily coating. The area under the carb is comparatively clean. The worst of it is at the bottom of the runners, including the tops (roofs) of those runners. I also swabbed the inside of the PCV vacuum line and found very little there. If this was coming from a rich carb wouldn't there be residue everywhere?
Is it possible this is a valve problem?