She bogged and hesitated going up the mountain yesterday, Q-jet is rich?
10-16-2003, 01:20 PM
#1
Burning Brakes
Thread Starter
She bogged and hesitated going up the mountain yesterday, Q-jet is rich?
OK, nothing beats driving your dead sexy all American black sportscar up the hill in beautifull sunny Hawaii ( actually it was raining ) and in front of god and the world she starts to hesitate and stutter. Does this mean she's rich or lean? Must i rebuild it to adjust this ...suspected ...richness? Can i adjust this with the mixture screws or is that only the idle? She idles at about 700RPM. Under 3500 RPM the car runs fine and is the usual fun to drive vette experience! Anything above this brings on hesitation, again i ask ..this is richness right? My ZZ4 is rated at 385hp/410tq, so if i rebuild ( which is 95% likely) what do i need to do in the rebuild to correct this richness. On the slim chance i do not decide to rebuild is a Edelbrock Q-jet replacement a good alternative?
10-18-2003, 05:00 PM
#3
Le Mans Master
Member Since: Oct 2002
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Re: She bogged and hesitated going up the mountain yesterday, Q-jet is rich? (sharkthehunter77)
Well I can’t tell how high that mountain is from here in California. But Holleys at least need a jet change leaner for every 2,000’ elevation increase. An engine will stumble when drunk with fuel and sometimes you can see the black smoke of too rich jetting.
Next then an engine will bog when too lean. This is from lean jetting or that secoundary air valve floppin open too soon. And lean can hurt pistons fast. Only way to tell here is try some different jetting and/or valve setting. Do it right and get a good book for this. No you can’t adjust jetting with the idle mixture screws. Mixture screws only adjust mixture at idle or just a few RPMs higher.
Q-jet is complicated carb and for a replaement the Performer carb by Edelbrock will get the job done for a lot less $$ and few headaches (simpler carb). You’ll need a Performer intake for this too as the stock itake won’t fit an squarebore carb. ;)
Next then an engine will bog when too lean. This is from lean jetting or that secoundary air valve floppin open too soon. And lean can hurt pistons fast. Only way to tell here is try some different jetting and/or valve setting. Do it right and get a good book for this. No you can’t adjust jetting with the idle mixture screws. Mixture screws only adjust mixture at idle or just a few RPMs higher.
Q-jet is complicated carb and for a replaement the Performer carb by Edelbrock will get the job done for a lot less $$ and few headaches (simpler carb). You’ll need a Performer intake for this too as the stock itake won’t fit an squarebore carb. ;)
10-18-2003, 05:29 PM
#4
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Re: She bogged and hesitated going up the mountain yesterday, Q-jet is rich? (sharkthehunter77)
My car would bog when going up hills also, and it turned out to be a bad fuel pump and cracked fuel lines. It also ran fine at lower speeds and on flat roads.
10-18-2003, 06:15 PM
#5
Le Mans Master
Re: She bogged and hesitated going up the mountain yesterday, Q-jet is rich? (sharkthehunter77)
Were your driving up Haleakala in Maui - sea level to 13,000 ft if I remember right in one of the shortest distances.
10-19-2003, 05:59 AM
#6
Burning Brakes
Thread Starter
Re: She bogged and hesitated going up the mountain yesterday, Q-jet is rich? (Larry82)
CardoO : The Performer is 600 CFM as compared to the 750 Edelbrock Q-jet replacement. Is 600 CFM enough. Right now my plan is to just save up for the Q-jet replacment...,but if the cheaper "performer" carb will do then what the hay!
Ben Taylor: Wow, ...broken fuel lines and a bad fuel pump.Who the hell did! you **** off! How did U find out it was the fuel pump as opposed to something else?
Larry82: Never driven the car on Maui but that sounds fun. I am in the Navy stationed on Oahu. All this talk of carberators is making FI sound better and better
Ben Taylor: Wow, ...broken fuel lines and a bad fuel pump.Who the hell did! you **** off! How did U find out it was the fuel pump as opposed to something else?
Larry82: Never driven the car on Maui but that sounds fun. I am in the Navy stationed on Oahu. All this talk of carberators is making FI sound better and better
10-19-2003, 07:27 AM
#7
Team Owner
Re: She bogged and hesitated going up the mountain yesterday, Q-jet is rich? (sharkthehunter77)
Before you spend time and money, pull out a couple of spark plugs to see if you have a rich or lean condition.
10-19-2003, 02:51 PM
#8
Burning Brakes
Thread Starter
Re: She bogged and hesitated going up the mountain yesterday, Q-jet is rich? (paul67)
How does checking the plugs tell me about te leaness or richness of the carb?