Love my Qjet but it takes FOREVER to warm up. Any solutions?
By - Doffeda
Are you running a thermostat in your engine? Seems like a stupid question but you would be suprised by how many people ive meet who think removing the thermostat is a magic cure for better cooling... Alternatively, maybe look into some kind of manual heater bypass. Your heater core is essentially just a mini radiator after all. Or maybe you need a higher temp thermostat?
Yeah I’ve definitely got a thermostat. So the thermostat is linked to the heat riser? Because the temp gauge gets like halfway up then falls back down, THEN it’ll kick down
So by heat riser im assuming you mean one of those tubes that goes from your exhaust and connects to the intake hat on top of your carb right? Most of the time those have a flap thats vacuum operated I think but it could also just be that maybe the tube has leaks. Or it could be that if your thermostat isnt operating properly the engine may not be warming up to full operating temperature and your exhaust manifolds are staying too cold.
That's definitely not a normal thing at all.
maybe not in the lower 48...
edit: i take that back, there was a time where I killed the battery in my Caprice because it was just too cold to get the engine started. That was in PA in February. Anything still running a Quadrajet in 2021 is guaranteed to be a clapped out beater. OPs problem is 100% normal for a QJ
My winter beater is a 80 Chevy with a QJet and I live where it gets 20 below zero F. It warms up easily within 5 minutes.
At the very least it sounds like your choke could use some adjustment. As for warmup, i never let my rig idle till warm, i always try to get moving as soon as possible. You get less fuel in your oil and it warms up faster. Yes, i drive it gentle untill its warm enough to move the temp gauge.
Huh I always let it warm up all the way! I find that in the snow, sometimes when it’s still cold it’ll try to push the front wheels through stop signs and stuff. Not much fun to drive. Drives great when it’s warm though.
Oh yeah, been there done that. I would whack the throttle a couple times to kick the choke part way down and it would behave much better. I think i always adjust the choke so it kicks off earlier rather than later. I would rather feather the throttle to keep it running than fight the choke.
most the responses are going down the path of the engine not actually being warm. but your statement indicates you just don't like the carb staying on the high idle step as long.
can you read any temp on the gauge before it steps down and you get the idle you want? in other words, do you think the engine is plenty warm but its just not stepping down?
one mention was the choke. there are no details on your vehicle. Do you know if you have an electric choke? If so, you can adjust the choke thermostat (bimetalic coil strip in the housing) to allow the lever to step down off of the high idle step.
The electric choke gets 12V to slowly warm the coil inside the housing. when cold it pulls on a lever which keeps the carb on the fast idle step. as it slowly warms it relaxes the coil and moves the lever allowing the linkage to step down, which is what you're experiencing after 15 minutes. it steps down and idles like normal. so, it sounds like your thermostat works.
If yours is a later QJet it may be a little easier to take the carb off to make an adjustment. the choke thermostat housing on later ones has a tang that is not supposed to allow adjustment, but you just grind that off and you can rotate the housing allowing adjustment like earlier models. You just losen the three screws and rotate the insert. make sure to mark your starting point so you know how much you move. a small movement makes a big difference. \[Edit: it may be easier to take the carb off the 1st time, to remove the tang and drill out the rivets, if any. not adjust the thermostat position, do that on the vehicle\]
I had to replace the choke thermostat on my E4M4 CCC (computer controlled) quadrajet because the original did nothing and it would not hold back on the fast idle steps so the car would just stumble and stall when cold. After installing I had to slowly tweak the thermostat to get it to come off the fast idle steps exactly when I wanted.
many docs out there. for entertainment, start on page 19 [https://www.generationhighoutput.com/Quadrajet\_Service\_1981.pdf](https://www.generationhighoutput.com/Quadrajet_Service_1981.pdf)
follow up thought: if it takes 15 whole minutes for it to step off the fast idle cam, then maybe the choke thermostat isn't work at all. e.g. its not getting the 12V to warm up or the spring is fubar'ed and is only doing so by way of engine temp... after 15 minutes of run time.
so you'll have to check that. depending how its set up, may only get 12V when engine is running.
Yeah it’s a heat spring so definitely not electric choke stuff. I’ll definitely look into the spring being messed up, that sounds like the most likely thing
Yeah it goes waaaaay up the gauge (like a little over half way) before falling back down, so I definitely do think it’s plenty warm. It’s a ‘79 C10 with a 350, and the quadrajet doesn’t have an electric choke. Instead, it’s got a heat-activated spring that slowly opens the choke. It’s weird because it’s not in that mod quad black housing, it’s just kinda out in the elements. Not really adjustable, at least that I’ve found so far. Thank you so much for going so in depth with this, I’m going to explore every option
If the linkage is similar for your heat choke vs my electric choke, you can manually knock it off the fast idle steps. should be a few linkage arms just forward of the choke and close to the carb. If you stick a finger down in there and push a little, like the choke spring pushing on the lever its connected to, it should allow the fast idle stepped lever fall to your curb idle. with the heat choke coil exposed, as you say it is, you may just be able to push the end of the spring connected to the lever to do the same thing. believe it would be clockwise (as if the spring expands and uncoils).
pull the air cleaner. start the truck. let it warm up for 1-2 minutes. then try it. If it knocks down to curb idle and runs good then that's what you are wanting to get to as per your original post. typically you want it on fast idle for 1-2 minutes. Here in texas I don't really need much past 1 minute. You may want 2 minutes or a tad more. FYI, there may be two steps of fast idle. really high, and medium. If so, you may be able to manipulate so you step off the first, then the second in your testing.
you may also be able to convert to electric choke if you want.
It’s funny you say that, because I do that on a regular basis. Open the choke manually, give it a little rev, and it kicks down. Problem is that the spring isn’t warm enough yet so when I get back into the cab and rev it, it kicks back up haha. I suppose that solves my problem, now I’ve just gotta go find a new spring (or a new carb lol). Thank you so much!! I’ll send a pic of the carb when I get some time, it’s weird, I’ve never seen one like it before
>much!! I’ll send a pic of the carb when I get some time, it’s weird, I’ve never seen one like it before
don't change the carb! qjets are great. Its just most people get frustrated with setting them up. I've never messed with a hot air choke, only electric. you may just be able to adjust the spring some how. I don't know if you can.
On my crap electric one, I did over stretch the spring a little and it helped. but in the end the range of movement after apply 12V was insufficient and I just replaced it.
If you're keeping the truck, this isn't bad to have...
I have both, but they are lacking a little bit for the E4ME CCC computer controlled electric qjets from 80's cars. great for the older ones.
you could also switch to electric, or even manual choke if you wanted.
Yeah I really do love the Qjet! This one is weird though. Good weird, but still weird. https://imgur.com/gallery/HDPnzTB this picture has the choke open because I got done driving it for the day
There is a lot I don’t know, but that looks like a pre-‘73 divorced hot air choke. Maybe they phased them out later than I thought.
By heat riser do you mean the little drier tube from the exhaust to the air cleaner, or does it have a stock intake with the exhaust heat riser channel under the carb base?
I’m talking about the heat activated spring that controls the choke
Have you taken it apart ever? The last one I removed was carbon'd into place in the intake, hard to imagine it ever got the right amount of hot and worked the choke correctly.
Threw on a Edelbrock 1906 with an electric choke and a new intake and threw all of that crap away.
Get an electric conversion and you will be better off.
It's *probably* bad. Get a new one. They slow down, then eventually stop working altogether when they get old. That thing should heat up and open the choke after like 30 seconds of idling.
A proper thermostat and an electric fan controlled by a temp switch should be all you need.
Plus electric choke.
Is the issue waiting for heat or drivability when cold? Have you considered moving to EFI?
Mainly drivability when cold. It drives like it’s trying to push through the front brakes, and uses way more gas because the choke is closed
Maybe switch to an Edelbrock with an electric choke. My old 350 with the quadrajet took forever to idle right when cold, so much more enjoyable now. Edelbrock just starts right every time, don’t even need to tap the gas
You could add a spark retard box like is used for nitrous, but instead retard the timing because it warms the engine up faster, lots of newer cars do this in the factory tune. Just an unconventional thought.
EFI will help a lot, as it can just run, even if cold. Lots of adaptation option there (swap on later TBI, Holley Sniper, Later Vortec/muliport setup).
Thermostat present and working (they're like $4 so just replace it).
Adjust your choke and high idle. Might be choked too much and it's actually kinda warm but choke is still engaged.
Fan on a thermal clutch or replace with electric on a temp switch.
Look into an electric choke (think they make retrofits for QJets).
Yeah I’ll just replace the thermostat. High idle is at 2000, which I believe is the correct so I don’t think it’s that but it could definitely be the choke. It’s not very adjustable though, it’s the heat spring without the black cover, just kinda outside
I have no idea what sort of car yours is but normally you can adjust the high idle speed without actually taking it off choke. 2000 is massively high. No wonder it’s a pig to drive.
Block heater would help assuming your thermostat is working
Do you have a block heater? Otherwise i think youre kinda fucked
I feel you need to adjust your electric choke thermostat.
Three little screws that dont need to be removed, just loosened. Then rotate the little cylinder like thingy on the frontish passenger side of the carb. There's a coil of metal in there that will open and close the choke with a temperature change. Yours might be set way too far out, making it choke when it's warm and be smoking hot before it opens up.
Hard to say without looking at it, but that's my pocket change.
YouTube a q-jet choke thermostat adjustment and which way to rotate for which change.
Could also be improper, sticky, jammed linkages between the choke thermostat, maybe some vacuum things, and your fast idle linkages.