Rich and Cold :-(
Thread Starter
Instructor
Joined: Apr 2001
Posts: 140
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From: Las Vegas NV
Rich and Cold :-(
For some reason, my '74 454 auto runs rich as can be when cold. Even to mid-temp it runs really crappy. It ran fine 'till a few weeks ago (I have little time to spend with her :cry ). So, I'm thinking either the pull off valve, or the choke (the thermostat-like thing on the intake, right?).
Or, would richness have to do with mixture? I thought the mixture screws adjusted for the whole range, idle and non-idle.
After everything gets up to operating temp, it runs just dandy.
Also, its an all stock Q-jet, I live in Las Vegas, at ~2,200 ft. It started running bad after the temps got above 100.
BTW, just got new photo, working on sig. If you are interested...
http://members.***.net/djlangford/072703-Corvette.htm
Thanks,
David :flag
Or, would richness have to do with mixture? I thought the mixture screws adjusted for the whole range, idle and non-idle.
After everything gets up to operating temp, it runs just dandy.
Also, its an all stock Q-jet, I live in Las Vegas, at ~2,200 ft. It started running bad after the temps got above 100.
BTW, just got new photo, working on sig. If you are interested...
http://members.***.net/djlangford/072703-Corvette.htm
Thanks,
David :flag
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Re: Rich and Cold :-( (djlangford)
Black on Black in Las Vegas? Man you gatta love corvettes to drive in that heat. :lol:
As for the "runs rich when cold and even to mid temps runs crappy ... after everythings warmed up ... its dandy" sounds like the choke blade isn't set right - closed to far. You need to get the books out (shop manual or whatever brand repair manual - yes can be found at local library) and find the adjustment for the choke. May have bend the choke rod for this (welcome to Q-jet ownership) to set choke valve/blade spacing. BTW Idle mixture screws adjust mixture at idle only while throttle blades (not the choke valve/blade) are shut or nearly shut. Rods and jets (or could say rods in thier jets) control mixture once off idle.
Now for every 2,000 ft altitude change Holley carburetors require a jet change (one number) and I assume the worst that Q-jets would too. If your fouling plugs or notice black exhaust smoke a step leaner is the way to go. :seeya
As for the "runs rich when cold and even to mid temps runs crappy ... after everythings warmed up ... its dandy" sounds like the choke blade isn't set right - closed to far. You need to get the books out (shop manual or whatever brand repair manual - yes can be found at local library) and find the adjustment for the choke. May have bend the choke rod for this (welcome to Q-jet ownership) to set choke valve/blade spacing. BTW Idle mixture screws adjust mixture at idle only while throttle blades (not the choke valve/blade) are shut or nearly shut. Rods and jets (or could say rods in thier jets) control mixture once off idle.
Now for every 2,000 ft altitude change Holley carburetors require a jet change (one number) and I assume the worst that Q-jets would too. If your fouling plugs or notice black exhaust smoke a step leaner is the way to go. :seeya
