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Better way to set E4ME electric choke?

Old 10-02-2007, 10:03 PM
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Better way to set E4ME electric choke?

What is the best way to set electric choke on a rebuilt E4ME carb on a stock 305 ’87 set-up?

When starting my car the cold engine revs from 1100 – 1500 -1100 etc. for ~15 seconds. Engine speed starts to rise and little backfiring kicks in but carb won’t release for ~10 very long seconds. I drive off leaving smoke still hanging in air and then car quits acting up. Rich choke?

Things done: disconnected computer from distributor & set timing to factory 500 rpm 0 degrees tdc, set correct curb idle speed ~500 rpm, have steady vacuum, saw secondaries open/close right, car always runs normal when warmed, and follow GM starting procedure (gas pedal to floor, release slow, & crank). Have been tying to lean carb by slowing setting it a little more clockwise each morning.
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Old 10-02-2007, 10:11 PM
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Re: Better way to set E4ME electric choke?

have you checked and adjusted the vacuum breaks(pull-offs)? If you are smoking, I'm betting the pull-offs arent opening up the choke as they should. It should kick down off of high (highest) idle seconds ofter start.
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Old 10-02-2007, 10:17 PM
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Re: Better way to set E4ME electric choke?

No, but I will check that out now - thanks!
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Old 10-02-2007, 11:15 PM
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Old 10-03-2007, 04:44 AM
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Re: Better way to set E4ME electric choke?

Thanks, don't have a Choke Valve Angle Gauge (yet).

There's almost no tension at all on the leaf type tension spring - I'll turn it a couple turns see what happens (couldn't be much worse).
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Old 10-03-2007, 08:14 PM
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Re: Better way to set E4ME electric choke?

Turning the screw in 2 complete turns realy helped the cold engine/carb start much faster and was more steady. Before driving home turned it in 1.25 turns again and had a pretty acceptable start.

both!

I'd like to adjust the carb using the Delco guide. Anyone know where a bubble gauge is sold? Not seeing carb stuff at favorite parts stores.
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Old 10-04-2007, 08:40 PM
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Re: Better way to set E4ME electric choke?

Sonix,
I was looking a reply where you posted a picture on a question like this (problems with idle when start up 04-15-2006). In that picture if the electric choke is turned CCW (in the direction of the green arrow) does that lean the carb?
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Old 10-04-2007, 11:38 PM
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Re: Better way to set E4ME electric choke?

The choke has no effect on "lean/rich" I wish they never labelled it as such, it's an outright LIE!
All that does it effect the DURATION (length of time), it stays on. If you crank it to "rich", (this is the direction that will CLOSE the choke air flap), that means it waits until the engine is hotter, before pulling off, and it will kick on when the car isn't as cold.
If you turn it to "lean" that means it needs to be COLDER before it kicks in, and will kick off earlier. In a nutshell at least.

"bubble gauge"?!? I wouldn't even bother with that type of archaic method. I probably listed how I like to set the choke in that old thread. On a dead cold engine adjust it until it just barely closes the choke. Then set the choke pulloff for 3/16" of an inch open or so, when the pulloff opens.
Do it with the engine cold, first thing in the morning, before you start it. Close the pulloff with your hand.

That's basic choke setting advice, I didn't read your info too closely. How is it running right now?
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Old 10-05-2007, 05:17 AM
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Re: Better way to set E4ME electric choke?

When starting it's still running a little rough (just enough to make me hope no one is watching)

I'll adjust later this morning -- thanks
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Old 10-05-2007, 06:53 AM
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Re: Better way to set E4ME electric choke?

Your problems may not be 100% choke related, although the choke is likely the biggest issue. Do you have a dwell meter and have you checked dwell of the MC with engine hot?

If adjusting the choke doesn't get you all the way there, I'd suspect a small vacuum leak throwing off your mixture. The computer may be able to compensate, but only when hot.
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Old 10-05-2007, 04:03 PM
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Re: Better way to set E4ME electric choke?

I set the choke (it was staying ~1/16th to 1/8th inch open) and... much much better! Better starting in the morning, at lunch, and at quiting time.

Still a little more to work on (almost shame-free start-ups now)... I will check the vacuum secondary tommorrow AM.

On the dwell... I am gonna need some background help.. can you fill me in or is there a previous thread on dwell 'splaining it?
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Old 10-06-2007, 05:08 PM
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Re: Better way to set E4ME electric choke?

There's tons of stuff on setting up the ccc-qjet in the carb forums. In simple terms, dwell is the measure of the cycle rate of the mixture control solenoid. The faster it cycles the leaner the mixture. The Idle Air Bleed (IAB) valve is normally adjusted so the dwell at idle is at 50% or 30 degrees on the six cylinder scale of a dwell meter, basically in the middle.

If you still have driveability issues after adjusting the choke, get a dwell meter and we'll help you out.
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Old 10-08-2007, 10:06 AM
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Re: Better way to set E4ME electric choke?

ok, the choke it self is finally set correct, verified by gas pedal to floor and slow release folowed by looking at the choke. and the electric choke opens correctly but, and someday there will be no but, but for today there's a but....

before cranking I put vacuum on the the choke pull off (vacuum secondary) on passanger front side of the carb and it didn't budge an iota (no amount of vacumm pressure between 5 to 15 lbs kept the choke pull off open. linkage worked correctly when pushing in arm on choke pull off and the choke valve opened ~ 1/4 inch too.

Is it replacement timefor the choke pull off?
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Old 10-08-2007, 11:50 AM
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Re: Better way to set E4ME electric choke?

Yes. You can double check it by depressing it then holding your finger over the vacuum port. It should not open back up. If it does, or doesn't close when vacuum is applied (like you probably did) then the diaphragm is bad and it needs to be replaced.
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Old 10-08-2007, 04:10 PM
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Re: Better way to set E4ME electric choke?

The choke pull off also failed the double check... waiting to hear from carb rebuild place about a part exchange... or off to AZ for a new one

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Old 10-13-2007, 09:27 PM
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Re: Better way to set E4ME electric choke?

This afternoon put on a replacement secondary vacuum and engine vacuum went from ~15 to ~18.

I'm curious about how timing is affected by a vacuum leak on a carb. Before, even with the vacuum leak, timing was set on factory specs using factor procedure. Now that the vacuum leak is fixed on the carb, does timing probably need to adjusted?
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Old 10-14-2007, 10:30 AM
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Re: Better way to set E4ME electric choke?

Timing should NOT need to be adjusted. The base timing is not affected by manifold vacuum.

The timing advance is controlled by throttle position and vac sensor readings. If you made a significant change to the curb idle stop position it could, possibly, affect TPS voltage at idle, MAYBE affecting when the advance is brought in. TPS is normally adjusted to provide 0.40 volts at idle. It's essentially a potentiometer that varies output voltage from a 5.0 volt source with throttle position.
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Old 10-14-2007, 01:38 PM
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Re: Better way to set E4ME electric choke?

Great, will drive it and see how it goes for a while
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Old 10-17-2007, 09:13 PM
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Re: Better way to set E4ME electric choke?

I'm about done with this post as my car is driving smooth after short just warm up. But I'd like to get the choke pull off set just right for cold start ups. About what temperature should the themostat override the choke pull off?

Here is why I ask:

CHOKE SYSTEM WITH VACUUM BUCKING SPRING - A spring-loaded plunger is used in the vacuum break unit on some 4MV models (Figure 32). The purpose of the spring, called a "bucking spring", is to offset choke thermostatic coil tension and balance the opening of the choke valve with tension of the choke coil. This further refinement of air/fuel mixtures because the coil, which senses engine and ambient temperatures, will allow the choke valve to open gradually against spring tension in the diaphragm plunger head. In other words, in very cold temperatures, the extra tension created by the thermostatic coil will overcome the tension of the diaphragm plunger (bucking) spring to provide less choke valve opening with the result of slightly richer mixtures. In warmer temperatures, the thermostatic coil will have less tension and, consequently, will not compress the spring as much thereby giving a greater choke valve opening for slightly leaner mixtures.

So I'd guess that over tightening the bucking spring on the choke pull off would result in a lean cold start with plenty of gasping. For now I've set the bucking spring screw to 2 & 1/4 turns in. Any advice?

http://www.bdub.net/manuals/Quadrajet_Service_Manual_1981.pdf
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Old 10-18-2007, 01:23 PM
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Re: Better way to set E4ME electric choke?

Got your PM Scooter. It seems like you're making this out to be harder than it really is.

Ok, so your question is about the setting on the choke pulloff / vacuum break? That thing you listed has a lot of foreign terms to me, little bit of mumbo-jumbo there.

So I listed this above:
I probably listed how I like to set the choke in that old thread. On a dead cold engine adjust it until it just barely closes the choke. Then set the choke pulloff for 3/16" of an inch open or so, when the pulloff opens.
So with the car cold, flick the throttle, it should close the choke blade. This is with the car off! Then with your hand, push the rod into the vacuum break until it stops. As you push it into the vacuum break, it'll start to pull the choke "flap" open. If the flap is open enough that you can drop a 1/8" or 3/16" drill bit into the carb, it's fine. Otherwise turn the screw until that's the place its at.

If this is misadjusted it'll stumble or stall on a cold start. When it's just right, you'll get into the car, tap the gas about halfway down, flick the key over and it'll crank once or twice, then fire up, RPMs will dip after the starter comes out, then the vac break will open and it'll raise the RPMS back up. Nice, smooth, etc.
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Old 10-19-2007, 05:19 AM
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Re: Better way to set E4ME electric choke?

Appreciate it - for me this thread and answer hits nearly everything on setting the choke and choke pull off.

Here's the last of my question. Apparently the service manual is saying the leaf spring screw on the choke pull off allows for fine tuning for colld weather situations. Here in Virginia it's still 71 degree F or 22 degrees C at 6 am, so for now this screw setting may not matter. But winter is eventually coming and if I read the service manual adjustment note posted below, the leaf spring screw could makea difference by limiting the amount the choke pull off initially opens the choke & prevent starting stumble. So at what temperature does an engine start to stumble bad during start up due to too much cold air bein allowed in the carb? I thnk this temperature would be the one to set the leaf spring to. Anyone got any ideas on this adjustment or cold weather carb starting?

Last edited by scooter500; 10-19-2007 at 05:25 AM. Reason: Automerged Doublepost
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Old 10-19-2007, 09:36 AM
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Re: Better way to set E4ME electric choke?

That "leaf spring" is the same adjustment screw that we're talking about. You can fine tune it over the winter, but 1/8" is generally a good "shotgun" effect, it'll work pretty good. That's one thing that has a "spec" and who wrote the spec, buddy in california for his 4 seasons, or buddy in detroit for his 4 seasons? So set it so it works right now, and if you notice it's not working as well later, tweak it a bit.
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