Howdy all got a question for ya. After sitting overnight (kinda cold out too) when I go to start it takes alittle while for the engine to warm up. Basically if I dont give it a little gas for awhile (couple mins) it goes to about 500rpm then coughs and dies. This is the first car Ive had with a carb so Im kinda stupid about it, but it seems like this isnt the way its supposed to be. Any thoughts
Thanx
Glenn

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First order of business is to verify proper functioning of your choke. After a night out in the cool air, that butterfly should practically SLAM shut when you press the gas.

You say this is your first carbed car? Well, you have to start 'em a little differently from injected mills. EFI and TBI systems have sensors to handle all of the cold start fuel/air/spark variables. You turn the key and the little computer does all the work for ya.

With a carb, you have to "set" the choke by pressing the accelerator all the way to the floor and then letting it all the way up. Don't touch it again. If your choke is functioning properly, you will only have to turn the key and she should fire right up, hovering in the 1500-1800 RPM range. May climb to two grand, but more than that can hurt your the engine.

Give that motor a couple minutes to warm up, then hit the gas and let off of it (aim for about 2500). This should disengage the choke on a warm engine.

Welcome to the wonderful world of mid-twentieth century automotive technology. For all of our collective gripes about computer modules/sensors/ECM's and all the other shade tree complications, modern fuel systems do allow you to just hop in, turn the key and go - immediately.

The flipside? Go to Taco Bell in minivan and you are absolutely anonymous. Go there in your Vette. Well, you get the picture.

Here endeth the lesson

John

AAhhhhhh ...
Thank you master
Alas my carburater kung-fu is not strong

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In time, grasshopper. In time.

"The journey of a thousand miles, begins with a single step."
Confucius 551-479 BC

"hovering in the 1500-1800 RPM range. May climb to two grand"
Well its starts up fine but the hovering thing (I do know about that, I fly on Helo's) aint happening. If my foot aint on the pedal it goes down till it dies
Thanx
Grasshopper

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Not to worry.

When the engine is cold, take the breather off completely. As you look at the carb (I'm just gonna assume this is a four barrel) there is a plate at the top of the primary (front barrels). That plate is mounted to a rod that extends outside both side of the carb body. That plate is the choke plate (also known as the "butterfly", Grasshopper). With the choke "off" that plate should be vertical (open) so that you can see down into the carb. Your mission, should you choose to accept it, is to get things set up so that the butterfly is closed (horizontal) when you "set the choke" on a cold motor.

WITH THE ENGINE OFF, pull/push the throttle wide open, then check the choke linkage on the driver's side of the carb. Move that linkage rod up and down. With the throttle open, should move REAL easy and the choke plate should close.

Get some carb and choke cleaner and blast all the crud off the outside of the carb and all linkages (rods). Be careful not to blow all that crap into your carb. Move the linkages as you clean. When everything is loose, try setting the choke.

Let me know what you find and if that solves your problem.

John

Hrm...I'm like the grasshopper larve here...I'll just contiune with my method of holding the foot gently on the gas until the car can shift into gear without dying.

Paragon
Should my hot idle in drive be in the sub 500 range?

Larval grasshopper Paragon:

Negative, Ghostrider.

That warmed up '75 350 should be idling @ 600 in Drive. Double check your cluster tach against a reliable tach/dwell meter if possible.

John

Thank you all. This will be my project for tomorrow. Truly the zen of knowledge runs freely like beer in this hallowed area
Grasshopper

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You may find turning the choke coil on the passanger side of the carb counter clockwise just about 1/4 inch may make a big difference in it staying on fast idle long enough. May the force be with you grasshopper. Oops, mixed my shows.
Reaching in from the front passenger side down low you will find the fast idle screw. Looking at the linkage you will see several "steps on the fast idle cam that the screw hits when the choke is closed. With the car warm, set it on the second step and you can adjust the idle to about 1200 to 1600 in park, depending on the specs, and the idle speed will be okay when cold on all steps. The screw on the drivers side is used to adjust the warm idle speed. Drop it in gear and set to 600 RPM. Make sure someone is holding the brake or the wheels are blocked. Once these are right the choke pull off on the right side, a vacuum pot with an adjustment screw, can be tweaked to prevent loading up or lean bog when driving cold. It should open the choke slightly when first started, then the choke coil will gradually open the choke the rest of the way. With a bit of tweaking you can get the car to run smoothly from cold operation to fully warm. Takes a bit of pratice to get it right.
Zen it's okay. (groan)

|UPDATED|4/11/2004 6:37:25 PM (AZT)|/UPDATED|

Woah...I'm way lost. Ken, the classes you teach you show pictures or an actual carb when you describe these things right? If not I may need to find a "absolutely minimum basics" course first!

the only thing I can remember with a screw and notches on the passenger's side is a bulbus metal housing with a black plastic cover. Of course when i bought the car two out of three screws were broken off inside the housing and I haven't messed with it since. (Car runs fine, starts cold and needs warming so I left it be, figured the carb was one of the more fiddly bits that I didn't want to learn on a daily driver with). Is this the piece that should be adjusted to the second step? if not, what is it? are the missing screws part of the problem? is it a problem to drive without fixing?

So many questions...but one day I may be a grasshopper. Maybe even a cicada!

O...the car used to idle around 600-650 hot in drive, but last winter when i came home for christmas that had dropped to 400-500...Nobody does much with the car while I'm gone.

Scot

If you can hold out for a while I am going to rebuild the Q-jet on my C3. I will take photos and show step by step. When I get there I will make it available for anyone who wants it. It may be a month or so before I get to it.

Aahh- the gospels according to John, and Ken Almighty.
How many miles are on these carburetor-impaired vettes? It sounds like they need the typical old-fashioned Q-jet adjustments. Or, possibly a rebuild.

Ken-when you rebuild your Q-junk, could you possibly scan the instructions for the adjustments that come with the "Jiffy Kit"? I think this will help a lot of people on this subject.
Al

"Not yet a guru, but not a novice" hahahahaha

I will be glad to scan them. Already in the back seat of my daily driver. I will try to get that up this coming weekend, the make the pictures when I do the job.

Hey Scott, that black plastic thing is the choke coil. Under the metal part it attached toward the front slightly, is the fast idle screw.

Sounds good. The step by step photos will definitely be appreciated! It'll probably be a month before i'm in the same state as my car anyway!

Scot

Great info, Zen Master Ken. I've been digging through my shop manuals, etc. to find some decent photos and/or sketches to help our friends along their journey. No luck yet. Plenty of photos, but none that scan worth spit.

Paragon, you must "enhance your calm." Didn't do a carb rebuild myself until I was about 22. Damn things made me nervous just to look at. That was more than five years ago. Okay, okay - it was A LOT MORE than five years ago.

As I said at the beginning of this discussion, the first order of business is to make sure the choke is functioning properly. And, yes, that bulbous black thing-a-ma-jiggy with the two broken screws is a choke coil which has more than just a passing effect on your cold start status.

Get out the carb and choke cleaner and make that fuel and air mixmaster shine. If your linkages (that would be the little rod-looking doo-hickeys ) aren't able to move smoothly and FREELY, you can turn screws until the end of time without ever fixing the problem.

Now that you have cleaned everything and have everything moving freely and have gotten your butterfly to flap her wings a time or two, go do everything Zen Master Ken says. He has much wisdom to impart from his training in the Bowtie Dojo.

You can do this! And, if not, a $45.00/hour specialist can fix whatever you destroy.

"Mind like parachute - only work when open."
Charlie Chan


John

Dumb sounding question...but...is there anywhere that carb and choke cleaner SHOULDN'T go? obviously not to be taken internally by me personally, but is it a bad idea to clean the inside of the carb? the intake? Much to learn eh?

Paragon
Doesn't have $45/hr....especially not for one of the few things that is almost good enough...Can't bust it! (not in the good sense! )

Clean everything except the vacuum pots. Not all, but some cleaners can damage the rubber diaphrams. If you do get cleaner in them, just start the car and run it for about 20 or 30 minutes to COMPLETELY dry out the chemicals. It will be fine.

WARNING You may want to drive the car to dry them out! You could end up cruising and take up the entire rest of your day! You would not get anything else done!

Gosh, Ken. That would be horrible.!
You, know; as I think about it there may be a microscopic speck of dust on my polished Edelbrock Performer. I'm sure that it will take at least half a can of Gumout to definitely eradicate it. I'd probably have to drive all night to dry that baby out.

Aw, shucks! Memphis or Atlanta? So little time, so much tread left.

John

Dust on the intake could cause an imbalance in the engine compartment. Better get to cleaning and start driving right away!

I have this problem also when starting it in the morning, just keep the a little bit of gas on it for about 30 seconds - minute and it is fine. My engine is pretty much brand new, 600 miles. Could it be the cam I have? It is more aggressive than stock. A friend of mine has a similar setup engine, and he has to do the same thing.

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|B|1981 Electron Blue Coupe |/B| Chevy 350, Bored .30 Over, 10.50:1 Compression, Polished Holley 4bbl. Carburetor(600CFM), 64cc Vortec Heads w/Polished Performer Intake, Mallory Wires, NGK Plugs, DUI Ignition, 10" K&N, SRP Flat-top Pistons, Xtreme Energy Comp Cam(487/490 Lift), Shift Kit, 2200 Stall Torque Convertor, Full Length FlowTech Headers, Full 3" Exhaust, Dual 40s Flowmasters w/No Cats, Smog System Removed

Kinda doubt it there, Jetlag. My 350 is also running a longer duration cam underneath a Weiand Stealth intake and a 1406-series Edelbrock 600CFM Performer carb. Has that gentle "lope" at idle.

I had the exact same cold-start problems that you guys are experiencing until I got the choke and the fast idle set correctly. The mechanical beauty of the Edelbrock is its simplicity - which can hardly be said of the old Q-jets. The choke coil is on the right, the only two idle screws are on the left, metering valves on the front. And a glorious absence of dangling linkages. Easy, easy, easy/

With the modified cam you MIGHT have to feed it a little more (enrich the mixture a tad) to get her to do right.

Good luck.

John

Agreeded, adjustments should do it. And the Q-jet is really very easy to set once you know what to do. Maybe this weekend I might get to mine, if the weather holds. It should be warm.

Like Scot, I've just come to accept that cold cold starts require a little extra play with the right foot to keep the RPM's around 1500. I usually need 2-3 minutes or so before she's warm enough to hold a grumbly idle at 600 completely on her own. In warmer summer weather, it really never seems to be a problem. My feeling is that I run too great a risk of screwing up the carb settings if I mess with it to deal with the minor inconvenience of cold starting.

~ Joe

This cold weather carburetor setting questions have me wondering if I've been doing it all wrong. The last carburetor car I owned was back in 76 (74 charger)so I don't recall what I did to set the choke. I pump the accelerator several times, the turn the key...starts right up to a fast idle, then after she warms up I tap the accelerator again. I'll have to try the set once than start method.

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|IMG|http://www.C3VR.com/member_uploads/6101_6200/6137/DSC00001.JPG |/IMG|

for diagrams of your carb.. (assuming it is stock quadrajunk)

goto www.carbs.net

they have a plethora of useful information about serial number decoding, parts, diagrams, etc..


heres the link to decode your serial number
http://www.carbs.net/quadnumber.htm

and an exploded view of the 4mv
http://www.carbs.net/diags/4mv.jpg

I have my Q-jet rebuilt and working quite well. I have many pictures. Give me just bit more time to put it in a document to send out. It will answer many question. I can send some disc out, but will need to find a place to post it as well. However, I want it to be free for anyone in C3VR, others I want to pay. I don't yet know how large the file will be.

please do, maybe ill practice on one of the two 69 vette 4mv quadrajunks I have in the shed..

hell i have three.. im running another one on my 80 chev 4x4

and it needs a rebuild... it's secondaries dont work..