Hi guys, I ordered (Rockauto) and installed a new Rochester Quadrajet. Manufacturer said everysthing is tested and adjusted. Hmmm, not really. It is almost impossible to start the engine when it is cold, as far I start it and stop hitting the throttle it goes out. When I keep the throttle pushed it runs. When the engine is warm it is running "ok" and I can make adjustments. Timing is Ok, spark plugs also Ok.

Due to the fact we do not have experts on this where I live (only european cars) I need some advice:

- When engine is warm I will adjust air/fuel ratio with vacuum gauge
- When engine is warm I can adjust idle
- What to check and adjust for the cold start, are adjustments on the choke necessary?
- Are adjustments on the fast (cold) idle necessary?

66´f85, 330cui stock engine, jetaway trans

Thank you very much, greetings from Austria. the one without kangaroos

 

more carb information would likely be helpful - what model number carb, is it electric or manual choke? Do you know anything about how it was rebuilt/remanufactured?


have you confirmed no vacuum leaks?


Hard to start when cold I believe is a fairly common Qjet trait (My 350 also takes a few tries when cold) but once engine running I don't think it should be cutting out like you've described.

 

First of all, it is not physically possible to completely adjust a rebuilt carb until it is on the specific engine and running. Any vendor who claims a carb is bolt and go is lying. Yes, there are specific internal adjustments (like float level) that are performed during a rebuild, but it is ALWAYS necessary to dial in the idle mixture screws, idle speed, and fast idle speed once the carb is on the engine.

Second, there is no difference in function between this carb and any European carb. The problem is that proper carb adjustment is a lost art and finding someone who can do it correctly is difficult anywhere.

Third, get a Chassis Service Manual, which will tell you exactly how to adjust the carb on the engine.

 

Do you really have a Rochester Quadrajet (spread-bore / verschiedende Drosselklappen) or an Rochester 4GC ( square-bore / gleichgroße Drosselklappen)

The quality of these cheap rebuild /reman carbs are sometimes questionable.

 

Does the issue with the cold starting occur after it sits overnight,or is it only when it is not started for a few days? If it starts Ok when just siting 1 night without being started,it will be easier to diagnose the problem. Let us know. Larry

 

I got a remanned qjet from rock auto, ASA I got it I disassembled and used the CSM and rugglues qjet book to set the carb up and I added an electric choke. IIRC I changed the main jets and rods for my application and then made sure every adj in the CSM was correct. Everything needed at least a tweak, the secondary air valve spring was way off and the float was off as well. The end result is the car starts easy and I can put the pedal to the floor from a standstill or any speed and there is no hesitation or backfire just BBO roar n smiles.

In short get the CSM and an e choke and go thru the carb as outlined in the CSM and you should be GTG.

 

I do have the service manual, but it´s not that easy to understand a few of the steps - and it is in englisch (not my first language). I will try to get it fixed

THX

 

It´s a spreadbore

BR

 

Its also when it sits overnight. I try to get it running - it never runs before with the new carburator. It did with the old one without any issues.

BR

 

I typed quadrajet choke adjustment on youtube and several videos showed up. Sometimes a video clears things up. Good luck