GMCforum: GMCnet » Electronic QuadraJet and factory Electronic Spark Control

Home » Public Forums » GMCnet » Electronic QuadraJet and factory Electronic Spark Control (CCC, ESC, E4ME, E4MC, E4MED, E4MEF)

Show: Today's Messages :: Polls :: Message Navigator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334297 is a reply to message #334294]

Sun, 01 July 2018 02:37

GMC2000

Messages: 193
Registered: March 2018
Location: Georgia

Karma: -3

Senior Member

from your link Quote:

On E4MED models, ... The idle speed solenoid, used primarily on air conditioned vehicles, maintains correct curb idle speed whenever the compressor clutch is engaged.

there was recently a topic about adding an idle controller for when the A/C compressor kicks in on here, it was interesting to read some of the suggestions. looks like this carb would do that without any backyard engineering.

the wiring diagram on that page shows an ECU and O2 sensor etc. still nothing concrete as far as exactly which trucks came with this though but there is some codes on the diagram

V8=LS9
K100(06) & LS9 & NB2
K100 (03) (06) & LS9

I know what LS9 is but whish I could figure out what the other codes mean, that seems like it would translate into something I could use to get all the right components.

I am getting the other CCC components I mentioned from that caprice but dont have anything to experiment on with them yet. on the look out for 455s now too and might end up with an engine before a coach. lol I have a lead on an early toranado thats been in a barn for decades. guy says it was wrecked and has some front end damage but not real bad just got to go look at it. its not a for sale deal, but he said he was sure they would sell it.

Edit to add: thats the diagram for the other one, the one that is electronic primary metering, not the one you have and the one Im trying to find.

[Updated on: Sun, 01 July 2018 02:48]

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334307 is a reply to message #333679]

Sun, 01 July 2018 08:03

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

Fred, 'lean burn' was the Mopar way of meeting emissions with a controlled carburetor. It did as lousy a job as everyone else's of the time, FI cured the problems. I had not any great problems with my carbureted coach - as long as it ate non alcohol gas. Summertime plus ethanol plus traffic adds up to potential problems in a GMC. I got the coach to survive with a new fan clutch, recored radiator, and dropping the engine driven fuel pump in lieu of a pair of electric pumps. It would then - by actual unfortunate test - survive thirty or forty minutes of downtown Atlanta Friday afternoon traffic without complaint.

--johnny

Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334310 is a reply to message #333679]

Sun, 01 July 2018 08:36

GMC2000

Messages: 193
Registered: March 2018
Location: Georgia

Karma: -3

Senior Member

the ESC is what Im most interested in but I also think that both of the GM electroQjets are worth more investigation and could be very useful.

Ive been meaning to ask about the popular e. fuel pumps that seem to be most recommended for these. the big carter ones, does anyone know if they can be doubled on the same line? specifically, if one can push fuel through another that is inline but turned off and also could they pull through another in line that is off?

I found some wiring diagrams that I think have what I need to run stand alone ESC. this is the best one so far: http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_352_86_1986_Chevrolet_GMC_Light_Truc_Wiring_Manual_CK_10_30_Only.pdf

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334315 is a reply to message #333679]

Sun, 01 July 2018 09:50

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

The Mr. Gasket pumps have backflow valves but presumably you could pull gas through one, although one has to ask why. Sucking the current stuff called gasoline in the summer is a prescription for vapor lock. All I can see cascading them would gain is one more point of failure. If you want to go to electric pumps for a carbureted system, here's how:

http://www.gmcmhphotos.com/photos/g6198-cane-9-creek-rv-park-heflin-2c-al.html

--johnny

DOS Tip: Don't use the supplied input filters. Pick up a pair of the Wix replacements. The originals will develop air leaks.

Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell

Report message to a moderator

Re: [GMCnet] Electronic QuadraJet and factory Electronic Spark Control [message #334318 is a reply to message #334315]

Sun, 01 July 2018 10:13

jimk

Messages: 6734
Registered: July 2006
Location: Belmont, CA

Karma: 9

Senior Member

You will not gain anything by going to 800 CFM carb as you will not rev up
enough to get there.
If you drag race, then you'll Need to address that.
I feel you guys can come up with an improvement with your trials.
I'll be following your progress

On Sun, Jul 1, 2018 at 8:02 AM Johnny Bridges via Gmclist <
gmclist@list.gmcnet.org> wrote:

> The Mr. Gasket pumps have backflow valves but presumably you could pull
> gas through one, although one has to ask why. Sucking the current stuff
> called gasoline in the summer is a prescription for vapor lock. All I can
> see cascading them would gain is one more point of failure. If you want to
> go to electric pumps for a carbureted system, here's how:
>
>
> http://www.gmcmhphotos.com/photos/g6198-cane-9-creek-rv-park-heflin-2c-al.html
>
> --johnny
>
> DOS Tip: Don't use the supplied input filters. Pick up a pair of the Wix
> replacements. The originals will develop air leaks.
> --
> 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> "I forgive them all, save those who hurt the dogs. They must answer to me
> in hell" - ol Andy, paraphrased
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334333 is a reply to message #333679]

Sun, 01 July 2018 13:55

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

Nor did I say anything about huge carbs, Jim Smile

Smile

--johnnny

Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell

Report message to a moderator

Re: [GMCnet] Electronic QuadraJet and factory Electronic Spark Control [message #334344 is a reply to message #334318]

Sun, 01 July 2018 15:18

BoboBob13

Messages: 49
Registered: June 2018
Location: Las Vegas

Karma: -3

Member

I have to disagree when you say "You will not gain anything by going to 800 CFM carb".

Yes it is true we don't need the 800 CFM on the top end but what you are really gaining
with a 800 CFM carb is an increase in airflow that is due to a larger primary venturi.
1 7/32 inch venturi = 800 CFM
1 3/32 inch venturi = 750 CFM

As we run around on the primary venturis 80% of the time this would help us out and also
maybe stay out of the secondaries as much.

Bob Broadwell 75 Eleganza II-Rebuilt performance engine, Manny trans, Manny 1-ton front end, 73 23ft with a side bath getting some updates-both living in Las Vegas

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334346 is a reply to message #334307]

Sun, 01 July 2018 15:28

BoboBob13

Messages: 49
Registered: June 2018
Location: Las Vegas

Karma: -3

Member

Best setup I have found so far for vapor lock is do away with the factory pump.

Install a good electric pump back by the fuel tanks-can use 2 pumps or a switching valve.
No fuel filter between the pumps and the tanks. Up front where the old pump used
to be install a 3 port fuel filter-3/8 inlet/outlet with a 1/4 return-they are a bit
hard to find. Then run a new line off the 1/4 side of the fuel filter all the way back to
the gas tanks and dump into the tanks.

Works well and this is where I got the idea from.

http://www.gmcmhphotos.com/photos/3-port-fuel-pump-2c-filter-2c-and-hot-fuel/p57439-3-port-fuel-filter.html

Bob Broadwell 75 Eleganza II-Rebuilt performance engine, Manny trans, Manny 1-ton front end, 73 23ft with a side bath getting some updates-both living in Las Vegas

Report message to a moderator

Re: [GMCnet] Electronic QuadraJet and factory Electronic Spark Control [message #334347 is a reply to message #334344]

Sun, 01 July 2018 15:35

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

If you really want poor throttle response on the bottom end, on vehicles
with tall final drive ratios, ( like 3:07 - 1 ) then just bolt on a big 'ol
Holley double pumper. It will fall right on it's nose. Same thing with a
big Quadrajet, or Carter AFB.
What you ARE after, is velocity in the inlet tract. This will promote
throttle response. This requires smaller, not larger primaries.
It was the reason for tri-power instead of one great big carb.
Don't have enough room on the net to explain further, but trust me on
this one. If you want a more in-depth explanation, catch me at a rally
sometime and we will add it to the bull session.
Bigger ain't better, no matter what your car guy buddies say.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Sun, Jul 1, 2018, 1:19 PM Robert Edwin Broadwell
wrote:

> I have to disagree when you say "You will not gain anything by going to
> 800 CFM carb".
>
> Yes it is true we don't need the 800 CFM on the top end but what you are
> really gaining
> with a 800 CFM carb is an increase in airflow that is due to a larger
> primary venturi.
> 1 7/32 inch venturi = 800 CFM
> 1 3/32 inch venturi = 750 CFM
>
> As we run around on the primary venturis 80% of the time this would help
> us out and also
> maybe stay out of the secondaries as much.
>
> --
> Bob Broadwell
> 76 Eleganza II-Rebuilt performance engine, Manny trans, Manny 1-ton front
> end living in Las Vegas
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334348 is a reply to message #333679]

Sun, 01 July 2018 15:44

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

The pumps I referenced need filters in front of them and the filters ship with the pumps. Any vane pump should have a filter in front of it. The pumps listed will deadhead without problems, there's no need for a return line. It doesn't show, but I capped the selector vale openings with push - on caps. The pumps are fed by the original lines to the selector, and the same switch picks up the relay for AUX. In this way you can revert to OEM for bolting a mechanical pump on and replacing the three hoses... no cutting necessary. Cured vapor lock in Georgia in July - August. Also, if you turn the ignition on for ten or fifteen seconds before cranking, it primes the carb for a quick start.
Go down to the Men's Mall and find an '05 or so Ranger pickup with a 3 liter Vulcan motor. Look on the firewall in the cab just above the passenger toeboard under the carpet. Under a guard bolted to the firewall is the turnover switch. The Ford one also shuts down on a certain G-force so if you hit something but the wreck stays upright and running it'll still kill the pumps. Use it in lieu of an oil pressure switch. I say Vulcan motor because mine had one, but i suspect the four cylinder and four liter ones use the same setup.

--johnny

Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334350 is a reply to message #333679]

Sun, 01 July 2018 16:21

GMC2000

Messages: 193
Registered: March 2018
Location: Georgia

Karma: -3

Senior Member

I prefer a return line but Im not sure the best way to do it on a Q-jet.

you can also do the safety kill by taping into the low oil pres sender or light itself without a special sender, run that to a relay then out of it onto the e.pump so it removes power when the light comes on. then use the ignition switch to starter solenoid for start up, some ignition switches even have a primer circuit built in just ahead of the regular starting position and also spring loaded and you can prime before going into the start position.

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334365 is a reply to message #333679]

Sun, 01 July 2018 19:01

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

well, what benefit will you gain by having a return line on a float bowl carb?

--johnny

Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334369 is a reply to message #333679]

Sun, 01 July 2018 19:14

GMC2000

Messages: 193
Registered: March 2018
Location: Georgia

Karma: -3

Senior Member

some carbs (some webers anyway) have recirculating float bowls, not sure exactly why, maybe consistent pressure, but keeping the fuel flowing seems like a good idea for keeping it cool too but also cleaning it for stuff that doesnt get used as frequently.

I use modular glass filters, for visibility reasons mostly and I route them safely and in some cases cover them for protection.

Report message to a moderator

Re: [GMCnet] Electronic QuadraJet and factory Electronic Spark Control [message #334371 is a reply to message #334365]

Sun, 01 July 2018 19:16

jimk

Messages: 6734
Registered: July 2006
Location: Belmont, CA

Karma: 9

Senior Member

My comments are backed by trial and error. Like JimH said you'll not gain
much unles you rev in 4,000

On Sun, Jul 1, 2018 at 5:12 PM Johnny Bridges via Gmclist <
gmclist@list.gmcnet.org> wrote:

> well, what benefit will you gain by having a return line on a float bowl
> carb?
>
> --johnny
>
> --
> 76 26' Eleganza(?) with beaucoup mods and add - ons.
> Braselton, Ga.
> "I forgive them all, save those who hurt the dogs. They must answer to me
> in hell" - ol Andy, paraphrased
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334412 is a reply to message #333679]

Mon, 02 July 2018 07:20

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

I agree, jim. I just wondered why you quoted my post and then mentioned high flow carbs. No matter. I think Hupy is correct, after I took the big one off my truck and put a Holley clone on it steams along much better.

--johnny

Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334470 is a reply to message #333679]

Tue, 03 July 2018 03:53

GMC2000

Messages: 193
Registered: March 2018
Location: Georgia

Karma: -3

Senior Member

Ive found more good stuff..

this is a fairly easy and inexpensive repair for worn throttle shaft bores with teflon bushings: http://rmcavoy.freeshell.org/Q_Jet_bushings.html

FWIW it does look like there is room in the throttle casting for small sealed ball bearings as those found on some weber carbs.

a link to the latest Q-jet manuals for all the spreadbore carbs. includes the two electronic ones: http://www.oldcarmanualproject.com/manuals/Carbs/Rochester/QJet/index.htm

and the best Ive found so far: http://truckroadservice.com/barth_attachments/7993991167_86_P30_service_part3.pdf this has both the E.Q-jet specs, All the ESC timing advance specs including the HEI module specs.

a rebuild including shaft bushings: https://www.hotrod.com/articles/ccrp-0908-qjet-carburetor-rebuild/

adjustment instructions: http://www.carburetor-blog.com/files/rochester_quadrajet_adjustments.pdf

BoboBob13, here is the wiring diagram for the E4MED:

http://www.73-87chevytrucks.com/techinfo/qjet/temp.gif

its a direct circuit with no ECU control like I thought it would have to be.

Edit to add: so the E4MED like the one you have (I think?) with its dual capacity pump is made to eliminate the cold stumble on the transition from idle to partial throttle. this would be very good to have with blocked crossover intakes IMO and it is an electric choke carb too.

there is also the M4MEF which is unique in that it is the only one that has air/fuel mixture screws on the secondaries.

check to see if your has the secondary mixture screws, IIRC this was only available on the 454/7.4l

[Updated on: Tue, 03 July 2018 04:48]

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334477 is a reply to message #333679]

Tue, 03 July 2018 07:32

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

If you want to use oil pressure to run a relay you'll have to add it. The GMC oil sender runs a gauge - it's a rheostat, not a switch. I'd rather not add stuff to the oil system with another porential leak. I'll use the Ford one.
If you hang a relay across a low oil light switch, you need a steering diode, otherwise the oil light is going to glow slightly.

--johnny

Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334482 is a reply to message #334470]

Tue, 03 July 2018 08:49

BoboBob13

Messages: 49
Registered: June 2018
Location: Las Vegas

Karma: -3

Member

2K

My 4M4ED only has mixture adjustment screws on the primary side-never seen or heard of mixture screws on secondary side.

The stock carbs on the GMC MH were 750 CFM with a 1 3/32 inch primary bore.
The carb I'm setting up is an 800CFM with 1 7/32 inch primary bore.
Why am I using this carb? It's what they put on the motor when they rebuilt it.

Waiting for some new primary rods to go with the jet set I bought along with a set of
drill bits from 0.3 to 3.0 mm so I can do some modifications. Using Cliff Ruggles First
Recipe as a start point and installing a AEM wide band Air/Fuel Ratio gauge so I can see where
I'm at and fine tune things.

Thanks for the wiring diagram-not sure if I will ever hook it up. As of now I don't have the solenoid
that goes in the carb. The temp switch is the ground and 39 is power but I don't see where they are
pulling power from. Would be easy enough to hook it up if there is a cold drivability problem.

Bob B

Bob Broadwell 75 Eleganza II-Rebuilt performance engine, Manny trans, Manny 1-ton front end, 73 23ft with a side bath getting some updates-both living in Las Vegas

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334488 is a reply to message #333679]

Tue, 03 July 2018 10:18

GMC2000

Messages: 193
Registered: March 2018
Location: Georgia

Karma: -3

Senior Member

I'll try to get my hands on one of those Ford safety tilt/impact switches to play around with. thats a good idea. at least for normal operations and adding a direct prime with it should take care of the rest.

the adjustable a/f screws would be great for anything that spends and extended amount of time @WOT. I use an A/F indicator for tuning too and also cylinder head temp senders and exhaust temp probes, with gauges still sometimes but the reading the O2 at least I would consider a must have on something as stressed/loaded as the GMC engine.

that best so far link really does have some good info! shows all the variances in the HEI distributors too.

but I wouldnt throw out a good mechanical ignition distributor either, I'd keep it handy as a just in case back up for who know what the future holds. I guess thats another reason in the back of my mind that I have such a thing for old school carbs etc.

https://i.imgur.com/9xZiEc2.jpg

https://i.imgur.com/9xZiEc2.jpg

that and the old boy scout motto just stuck with me I guess.

[Updated on: Tue, 03 July 2018 10:19]

Report message to a moderator

Re: Electronic QuadraJet and factory Electronic Spark Control [message #334507 is a reply to message #333679]

Tue, 03 July 2018 13:29

jhbridges

Messages: 8412
Registered: May 2011
Location: Braselton ga

Karma: -74

Senior Member

I looked at some reference material on the 'electronic' Q-jet. To use one would be an interesting exercise in getting it to work, as would an AFB or a Holley. However, other than the accomplishment, I don't see where it would help things at all. The 'get-by' emissions carbs represented the worst of both worlds. You've still got a carb which is dependent on airflow through a venturi to pull gas into the stream from an atmospheric float bowl which can get hot and vaporize. But you've still got to hassle with a controller to make it work 'properly'. The 'recirculating' carbs that I've seen merely return fuel to the tank when the float valve is closed, they don't pressure the float bowl. Consequently,other than cooler fuel in the lines, there's no benefit and Weber sees you coming when you go to buy one. I'm like the old maid at the party, I'll dance with the one what brung me. You go ahead though, and report back.

--johnny

Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons. Braselton, Ga. I forgive them all, save those who hurt the dogs. They must answer to me in hell

Report message to a moderator

Pages (3): [ « ‹ 1 2 3 › »]

Previous Topic:	[GMCnet] Posting photos on the net
Next Topic:	Leak in air line

Goto Forum:

-=] Back to Top [=-

Current Time: Tue Jun 25 00:55:12 CDT 2024

Total time taken to generate the page: 0.01238 seconds