Re: More engine compartment and "what is this"?
 

[QUOTE=ChevyTech;2045592]well, my wife says I am obsessed with Chevy trucks. I don't get it. :lol:

Slonaker

Re: More engine compartment and "what is this"?
 

Being a California vehicle, yours may. I can’t say no for sure. Looking at his photo I knew it was not a computer controlled carb.

So does your 1986 CA emissions truck used a computer controlled carb and an ECM?

Re: More engine compartment and "what is this"?
 

unfortunately yes...computer controlled..its very primative though. Only thing the computer controls is the idle. It controls the mixture of fuel and air while car is at a stop.

Re: More engine compartment and "what is this"?
 

Compared to the computer control carbs that few people can work on and with all there vacuum switches, thermo vacuum valves and other parts that can fail on on that system, the TBI systems are simple.

Re: More engine compartment and "what is this"?
 

I think (but I am not sure...) that '86 CA emissions pickups use a computer controlled carb. The original poster, whose truck we are attempting to identify parts on, said he does not have CA emissions.

Slonaker

Re: More engine compartment and "what is this"?
 

yeah its very simple. actually i really dont see the need for the feature. But who knows what GM was thinking. Fuel injection systems like tbi can be simple you just have to take it one step at a time. People see all the wires and what not and right off the bat they are forget it. I use to have a vette that was tbi controlled an 84..It was a beast of a task at first but once you know your way around it its ok....I learned about fi before i learned about carbs ironic. lol

Re: More engine compartment and "what is this"?
 

what I have a question about..not to take away from the original poster. is about the smog tubes...why is it that some trucks have 4 air tubes coming from the exhaust manifold while others have just one...This is where everyone gets quiet lol

Re: More engine compartment and "what is this"?
 

A.I.R. tubes put oxygen into the hot exhaust to finish burning any unburned fuel.

I would think the four tube setup would get the oxygen in where the gases are the hottest. Maybe one tube was good enough to get it past the emission testing and was a few pennies less to build.

Re: More engine compartment and "what is this"?
 

Yeah i know the function of them. I just dont know what type of headers to get for the truck based on this. The original poster has smog tubes like mine. ONE tube on the front of each exhaust manifold. The other manifolds i have seen have 4 air tubes coming out of the bottom that connect to a single tube. I dont see how they fit onto thorley headers that have bungs holes on the top being that the 4 air tubes come out from the bottom and turn up at a 90 degree angle.

Re: More engine compartment and "what is this"?
 

take a look at a stock exhause manifold with air tubes..then look at a set of thorleys with bung holes..you will see what im talking about

Re: More engine compartment and "what is this"?
 

"These carbs aren't computer controlled as many people think. The only thing electrical about them is the dual capacity pump. The carb has to be plugged to the sensor in the thermostat housing in order to work right. If it isn't, the pump solenoid will stay closed all the time and waste fuel."

What does he mean when he says waste fuel? I removed it from my truck and installed a chrome thermostat housing. I suppose fuel economy goes south. I want to do a intake/carb swap in the future. Hopefully I can gain some more performance with these modifications. The trucks runs alot better with the air pump removed. I read somewhere where the dual capacity pump can cause the vehicle to stumble and stutter. That was reason enough for me to not use it. I'm not into fuel consumption if its not done by a overdrive transmission. I'm even open to Holley double pumpers on automatic tranny vehicles.

Re: More engine compartment and "what is this"?
 

Hey SHRTBX checked this post out. It may help you out.

http://67-72chevytrucks.com/vboard/s...d.php?t=217997

Re: More engine compartment and "what is this"?
 

SHRTBX: Swervin Ervin has some smog legal headers on his truck. Edelbrock, maybe? I'm not sure. He might be able to help you with the header issue, though he does not have a CA truck.

Slonaker

Re: More engine compartment and "what is this"?
 

Let's get some final answers. If we can all agree, I will edit the original posts with the proper labels beside the pics.

First pic, circled in gray = Temp sender to dash

Second pic, circled in blue = nobody has an answer yet

Third pic, circled in orange = knock sensor

Fourth pic, circled in
red = Solenoid Dual capacity pump
purple = temp switch?
yellow = a/c idle solenoid

Please let me know if this is correct.

Re: More engine compartment and "what is this"?
 

Spin your breather pipe out of the way and take better unobstructed pic of the blue one !

Re: More engine compartment and "what is this"?
 

Are we sure the red one is not a TCC switch for the tranny?

Re: More engine compartment and "what is this"?
 

red circled device is the mixture control solenoid. I have checked this via google and many online parts stores.

I will take another pic later today of the "blue" circled device.

Re: More engine compartment and "what is this"?
 

I think that the red one would be a mixture contol solenoid only if it was a computer controlled carb.

Slonaker

Re: More engine compartment and "what is this"?
 

I hesitated to reply to this thread because people get it in there mind these M4MED carburetors are computer controlled and become the obstacle to any progress in helping them.
I will say this one last time and then stay away from this post.
The carburetor in the photo is NOT computer controlled with a mixture solenoid; it's a M4MED q-jet.

Look for Part #260 at this link
http://www.tocmp.com/manuals/Carbs/R...age056_jpg.htm

Look for Part #260 at this link
http://www.tocmp.com/manuals/Carbs/R...age057_jpg.htm



Here are some more links you my want to look at about the same subject.
http://67-72chevytrucks.com/vboard/s...ad.php?t=82405

http://67-72chevytrucks.com/vboard/s...ad.php?t=72313

http://67-72chevytrucks.com/vboard/s...ead.php?t=3950

http://www.thirdgen.org/techboard/ca...jet-305-a.html


Slonaker is trying to help you, try and listen.

Re: More engine compartment and "what is this"?
 

http://www.tocmp.com/manuals/Carbs/R...age056_jpg.htm
part 260

http://www.tocmp.com/manuals/Carbs/R...age057_jpg.htm
Solenoid Dual capacity pump.

--------------------
So this is the name for it? Solenoid Dual capacity pump
Or is the name getting lost in translation? Is it also called mixture control solenoid, or is that something different all together?
Just want some clarification.
thx all.

Re: More engine compartment and "what is this"?
 

I am trying to learn here, I do know now that the carb is NOT computer controlled, but different answers had me confused as to what the actual part name was. Chill dude, it's only a part...

Re: More engine compartment and "what is this"?
 

I don't know if this was answered, or if it even matters to you, PCMCOBRA. And I'm not suggesting that it controls the carb, but on my 83, the ECM was on the inside firewall, under the dash, behind the glove compartment. As far as I can tell, mine is a low altitude federal. BTW, mine never came w/ AIR pump(s), according to the sticker.

Re: More engine compartment and "what is this"?
 

Like I have said before, I'm sorry for pointing you in the wrong direction. Like ChevyTech has said #1 YOUR carb is not computer controled and #2 The red circled item is the duel capacity pump solenoid. When i first looked at the pic i didn't notice that there was no plug on the front (indicating a computer controled cab). I'll shut-up now and let some of these other guys help you.

Al

Re: More engine compartment and "what is this"?
 

Hey all,
thx for the responses. A little confusion somewhere, but glad we are getting somewhere. Just trying to get the info, because I did not know. Learn something new everyday.
thx

Re: More engine compartment and "what is this"?
 

Her is my assessment. If I am wrong, I hope someone will correct me. It looks like several people will. :)

There are two types of quadrajets from this era. They look very similar. They both have an electrical plug on them in the same spot, whcih leads people to believe they are the same carb. The connector serves a different function on each of them.

M4MED
This is the carb in pcmcobra's pic. It is not computer controlled. It is found on '85 and '86 federal (AKA non california emissions) pickups. The electrical connector is for a dual capacity accelerator pump solenoid. The accelerator pump squirts one amount of fuel if the sender on the thermostat housing indicates a coolant temp of under 170degrees fahrenheit and another amount if the coolant temp is above 170.


E4ME
This carb is computer controlled. It is used on cars from this era, and possibly trucks with California emissions. The electrical connector on it looks very similar to the one on the M4MED, but is for the mixture control solenoid. The truck's computer controls the carb's air/fuel mixture somehow with this solenoid.

Slonaker