Q-Jet Queries

[MontesbyE]

Hi folks , i need a 2nd or 3rd opinion as I keep 2nd guessing my self .
quick background update; elcamino 305, I've removed all the smog pump gear and installed headers with Co2 sensor in rh pipe line.
I've seamy rebuilt the 4barrel q-jet, new throttle positioning sensor, new mixture control solenoid and float system and are confident with float height etc.
The engine starts and runs easily but is running very rich, i.e black sooty plugs , black exhaust etc
part of the smog system had a vacuum line feeding off the front bottom of the carb T;d into the vacuum line that runs to the rh rocker cover.
if i block this air feed it runs a bit rough and idles lower , unblock it and it idles higher , still rich tho.
do i need to remove the small plugs and wind the 2 idle needles out to compensate or - have i got the main metering rods to high- or low , its got me buggered .
I've read a lot of the posts on here all ready but none quite the same so any input would be greatly appreciated.
cheers Guys ,

First thing you should do is check your timing. Second get a vacuum gauge so you can properly adjust your carb with the two screws under the caps. There are only like two different types of the metering needles, they are computer controlled. That's the clicking you hear when you first turn the key. Don't mess with them. Cap off all the vacuum lines except to your PCV and the brake booster. The only other line still hooked up will go to barometric pressure sensor on your wheel well. Make sure your gaps on your plugs are within spec. If you don't know when the last time they were changed, its time. One could run a hotter range plug also. That's what Id start with. ✌

 

[tellboy]

MontesbyE, thanx for input , your advice is along the lines i was thinking.
ill try your subjections , but if the computer stuff keeps creeping in ill dump the lot and go new carb and dissy.
some one over here thru in the idea that our petrol is rubbish compared to the states and should go for the highest octane we can get -96 or 98, that could be a possibility as well.
ps bare with me here- whats PCV

 

[tellboy]

Hey guys, I just watched the 81-83 ccc videos in the resources section, bloody hell that's some sh.. to mess with your head, and i thought tuning the carb would be a breeze.
top points to whoever researched and posted those vids, there's every piece of information you could ever want in them, there some serous homework to swat up on.
cheers Tellboy

 

[MontesbyE]

MontesbyE, thanx for input , your advice is along the lines i was thinking.
ill try your subjections , but if the computer stuff keeps creeping in ill dump the lot and go new carb and dissy.
some one over here thru in the idea that our petrol is rubbish compared to the states and should go for the highest octane we can get -96 or 98, that could be a possibility as well.
ps bare with me here- whats PCV

For sure, run the better gas. The PCV is the pressure valve for the engine. Have you put a new cap and rotor in? Are you running a HEI distributer? Things to think about. Another thing is your choice of plugs. Dont fall for the shiny package and 17 probes sh*t like that. Good old fashioned autolites is what the older engines like.

 

[fleming442]

Positive Crankcase Ventilation

I'm going to disagree on the fuel. Too high of an octane rating without the compression to support it can degrade performance. You can try it, but I wouldn't fill it all the way up. If it's still 7.9:1, you could probably pi$$ in the tank and get good mileage. Or, is it kilometerage? 🤔

 

[pontiacgp]

Positive Crankcase Ventilation

I'm going to disagree on the fuel. Too high of an octane rating without the compression to support it can degrade performance. You can try it, but I wouldn't fill it all the way up. If it's still 7.9:1, you could probably pi$$ in the tank and get good mileage. Or, is it kilometerage? 🤔

your ahead of the game again....

Definition of kilometerage | New Word Suggestion | Collins Dictionary

Definition of kilometerage | New Word Suggestion | Collins Dictionary

www.collinsdictionary.com

 

[Clone TIE Pilot]

Check your fuel pressure. If your pump is putting out too much psi you will never get the engine tuned right. Its a pretty common problem anymore.

 

[MrSony]

ditto. add an inline regulator and set it to 4.5/5psi. Even tho im not running the CCC it helped it run a bit better back when i did it.

 

[RegalBegal]

Another common Q-jet problem is leaking plug wells. Usually the fuel bowls will leak out when the car sits although I have seen them so bad they cause a rich condition. Just my 2 cents.

 

[TMar365]

Hi folks , i need a 2nd or 3rd opinion as I keep 2nd guessing my self .
quick background update; elcamino 305, I've removed all the smog pump gear and installed headers with Co2 sensor in rh pipe line.
I've seamy rebuilt the 4barrel q-jet, new throttle positioning sensor, new mixture control solenoid and float system and are confident with float height etc.
The engine starts and runs easily but is running very rich, i.e black sooty plugs , black exhaust etc
part of the smog system had a vacuum line feeding off the front bottom of the carb T;d into the vacuum line that runs to the rh rocker cover.
if i block this air feed it runs a bit rough and idles lower , unblock it and it idles higher , still rich tho.
do i need to remove the small plugs and wind the 2 idle needles out to compensate or - have i got the main metering rods to high- or low , its got me buggered .
I've read a lot of the posts on here all ready but none quite the same so any input would be greatly appreciated.
cheers Guys ,

It's a few years, like 15 since i rebuilt my Quadra-junk. I believe you have to set the metering rods with a dwell meter, if memory serves me right.