1983 Monte Carlo saga: GM CCC Quadrajet , Starter

[Crosley.In.AZ]

I've been looking around for a gauge kit Thexton 370  to setup this CCC Quadrajet carb. Gauges are used to adjust lean and rich settings on the carb

It seems the gauge kit is hard to locate.  I can not find a spec for the length of the tube to set the lean side of the plunger

[wayne petty]

this might work...

http://www.arctictools.com/hand-tools/19650-thexton-adapter.html


i measured mine before i lost it..

39MM from the tip to the beginning of either scale..

32nds on one side... mm on the other...



the shaft tool is for adjusting the APT double D thru the removed plug or with the cover off..

the shaft tool is a borroughs special tool i got off the mac tool truck decades ago... i should probably stop my local mac tool guy see if he has any 370s left on the truck..


in the vent tube you hit the top of the primary rod holder..

in the slot just before the secondaries .. you check the float level..

the additional tools in the 370 kit ..

the BENT one is the lean limit on feedback quadrajets..  allows the assembler to preset the downward motion of the metering rods by the plunger.  there is a rich limit that should be set 4/32 above the downward max in feedback quadrajets..

the J shaped tool is to adjust the air bleed on the top of the feedback quadrajets..

the air bleed in the top has to bounce up and down with the 10 pulses per second to keep the air fuel ratio equal with the air bleed volume..


one warning.. just in case... with feedback quadrajets.. if one has increased the engine displacement .. say using a 350/355/ 383 stroker with a 305 carb... its NOT going to work well.. but there is a chance to make it work..
find an 81 caddy full size from california with the cast iron 6.0/368 motor with feedback carb... those can be used on a 350/355 engine swap with enough extra fuel available for the system to compensate...  a 383 stroker is stretching it right at the ragged edge of being able to run..

in addition.. please on feedback carbs.. use a dwell meter set to 6 cylinder scale..  to verify operation.. 28 to 36 degrees of dwell on the idle mixture solenoid green connector at idle.. and at 2500 RPMs in park...  if the system is working properly and able to control air fuel mixture...

remember these feedback carbs with 305s could get 23 MPG.. V6s could get 26 MPG..  when everything worked perfectly..


i know this is more than you ask for...  my fingers were bored...


APT adjustments... dry hop the car or truck...  where you punch it kinda hard from a complete stop at IDLE..

if it hesitates... give the tool a quarter turn counter clockwise... dry hop it again.. hesitation.. another quarter turn counter clockwise..  keep going till the flat spot off idle is gone...

when you hold the primary rod holder down with the apt tool.. you will feel that the APT screw comes up almost 3 turns from the lowest position before it starts to lift the metering rod.. give it about a turn and a half up from where it just touches as the starting point..  you will probably find a sweet spot somewhere between 2 1/4 turns up from first touch to 3 turns..  depending on your primary jetting and metering rods..

and something thats NOT in the book.. use the 370 dipstick or your own home made tool to verify that at idle. in drive. that the power valve spring is overpowered by the manifold vacuum.. so the primary metering rod holder is fully seated down by the vacuum..   quadrajets come off idle transition very early... this is the LEAN limit on the mains...
so as the throttle opens deep into the idle transition slots.. the main circuits start to flow.. if the APT is set too low.. it will be TOO LEAN as the mains start to flow and you will have a flat spot until the vacuum drops and the primary rod holder lifts allowing more fuel..

if the APT is set too HIGH.. you may also have a flat spot.. but fuel economy is going to be horrible...

i would like at this point to thank  C9  (rip) for teaching me about fuel economy on carbs..  gone but not forgotten..

[tomslik]

uhhh, WHAT power valve spring?

been into more of those semi controlled fuel leaks than i wanted to and have NEVER seen a "power valve"....

i'm sure you know about checking the air horn for it being flat, biggest issue i've seen for ANY q-jet...

[Crosley.In.AZ]

Wayne, thanks for info. I am not fully the adjustment with hook tools. The adjustment with tube type tool, I understand

Will have more questions soon

This car had the 305 replaced with a 350 crate engine 15 yrs ago. Probably 90 k miles on the 350 now

[wayne petty]

Wayne, thanks for info. I am not fully the adjustment with hook tools. The adjustment with tube type tool, I understand

Will have more questions soon

This car had the 305 replaced with a 350 crate engine 15 yrs ago. Probably 90 k miles on the 350 now

for the electronic quadrajets and half quadrajets called dual jets..

[wayne petty]

uhhh, WHAT power valve spring?

been into more of those semi controlled fuel leaks than i wanted to and have NEVER seen a "power valve"....

what i call the power valve spring... and i know there is a different name for it... but i don't recall it ...

is the spring UNDER the primary metering rod holder..

vacuum pulls the primary rod holder downward..  leaning out the fuel mixture by reducing the open area of the primary main jets...  when you step into the throttle and manifold vacuum drops.. the reduction in vacuum allows the spring to push up the metering rods enriching the primary air fuel ratio of the mains.. hence power valve spring..

with modified motors. if the primary metering rod holder is not fully seated at idle in gear.. you will have fuel mileage issues.. so a little experimental tweaking might be required.. this is NOT something for the first or even fifth time carb builder.. this is an advanced tweak.. i probably should not talk about it..  its the same as changing the primary rod lifter springs on an AFB... you want the metering rods to be fully seated at idle in gear.. so when the mains start flowing.. they are at their proper starting point for the air fuel mixture...

sorry if i confuse people with this as my fingers cannot type as fast as i think... and the brain cannot properly describe via my fingers what i know..

it took me a LONG LONG TIME to really learn this stuff and be able to describe it .. and since the APT is not adjustable.. i have had to improvise.

the last quadrajet i worked on belonged to a shop owners pickup truck.. i had him in his shop parking lot.. 50' x75' punching the gas from an idle in drive.. you should have seen the smile erupt when i got the apt adjustment right after about 8 or so quarter turns..   the old man with the boat.. when i finally got him to let me rebuild the quadrajet on his... he drove it around the shop area he was in a dozen times... said he had no idea the quadrajet could drive that well..
and all this is without getting into the secondaries...

there is a power valve spring for the secondaries after you get the primaries working...  the secondary air door valve spring adjustment.. in one quadrajet manual page.. it lists the fractions of a turn for this...  from 1/2 a turn thru 15/16 of a turn..  in 1/16 fractions..  instructions for this are on every carb build sheet...  it is worth trying different settings... on modified motors.. 1/16 of a turn at a time to find the sweet spot when the secondary air doors start to open.. .

want to know a quadrajet secret...

look at the notches out of the front of the secondary air doors...



when the secondary throttle plates start to open... there is not enough air flow to pull the secondary air door open.. but the airflow thru the notches lowers the pressure and causes fuel to be pulled up and dispensed by the tiny opening in air horn right there...  this gap was mostly found on pontiac versions..  its there on other models.. but without the notch focusing the air directly over the opening..  this is a 72 GTO carb..

[wayne petty]

and lastly a HUGE trick that i use sometimes...

when taking a quadrajet apart..

instead of driving the roll pin inward on the accelerator pump lever to free it... take off the base plate first.. you can at that point rotate the base plate around to allow the accelerator pump link to come off .. this saves wear and tear on the air horn bosses...

once we finish with this thread.. it might be moved or kept here and linked in the tech section..

[tomslik]

uhhh, WHAT power valve spring?

been into more of those semi controlled fuel leaks than i wanted to and have NEVER seen a "power valve"....

what i call the power valve spring.

THAT has no vaccum to it, the mixture control solinoid makes the holder (pintle, if ya want to get technical) go up and down, not vaccum.
find the green connector near the carb (that's not plugged in to anything) and hook up a analog dwell meter set on 6cyl, that's the dwell of the MC solinoid (shoot for around 30-40 degrees)

[Crosley.In.AZ]

OK ...  I am begining to understand.  

I talked to a friend, asked him if he had any of these old tools. He said yes, He understood exactly what I was looking for.  IF he finds , them, I will have more questions

[wayne petty]

uhhh, WHAT power valve spring?

been into more of those semi controlled fuel leaks than i wanted to and have NEVER seen a "power valve"....

what i call the power valve spring.

THAT has no vaccum to it, the mixture control solinoid makes the holder (pintle, if ya want to get technical) go up and down, not vaccum.
find the green connector near the carb (that's not plugged in to anything) and hook up a analog dwell meter set on 6cyl, that's the dwell of the MC solinoid (shoot for around 30-40 degrees)

sorry... i was discussing 2 different quadrajet models kinda interchangably...

the E4ME or E4MC versions which are feedback and  are electronicly controlled by the primary rod device pulling down 10 times per second do not have any vacuum control on the primary metering rods..

the M4MC, M4ME quadrajets with and without aneroid have a vacuum operated metering rod lifter.. that is limited in its downward motion by the APT...


and Tony... i did paste a link to someone who probably has a set for sale...

i have the J tool for the air bleed and the bent tool to limit the downward amount of the plunger... to set lean mixture..

so... which one are you actually working on...  

the feedback version.. or the NON feedback version...

i did not ask earlier as i described both...

[Crosley.In.AZ]

and Tony... i did paste a link to someone who probably has a set for sale...

Wayne :  only I see posted for tools, goes to a web site where it says tools " not available"

Carb I am working on is a E4ME

17083204 number on side.  OE carb on this Monte

[wayne petty]

I missed that small detail..

did you just need the plastic dipstick...   39MM from the tip to the start of the scale..  easy to replicate..

or i can loan you my other tools..  the J hook and the bent lever.. i know where they should be..

i have 2 places to call tomorrow.. if i recall.. there is a tool store nearby that has a LOT of older stuff... that might have it.. and my mac tool man i have been buying stuff from for 30 years...

here is an instruction site on the E4ME carb...

http://www.autozone.com/autozone/repairguides/GM-Astro-Safari-1985-1996-Repair-Guide/CARBURETED-FUEL-SYSTEM/Carburetor/_/P-0900c152800a80d8




i also found pages on the proper caddy donor carbs..

the except fed carb... 17080530 is an E4ME feedback carb for the 368 caddy in 1980...

http://www.gmpartswiki.com/getpage?pageid=53139
3.792 is the primary main jet..  17063495 but those don't show up elsewhere..  i have a few feedback carbs laying around the core pile.. i guess i will have to get out the gauge pins and dial calipers and start measuring. the primary calibrations..

http://www.gmpartswiki.com/getpage?pageid=53144

http://www.gmpartswiki.com/getpage?pageid=53146

the last few of these that i got my hands on..  i just supplied the carb to the owner and he installed it .. but they are really hard to find..

and i did not think about measuring primary jet diameters and metering rods...

there are 350 chevy calibrated E4me carbs around..  out here in california.. we usually just got 305 motors .. not 350 motors..

having a scan tool to hook up to the aldl port and going thru the live data really helps...

and leaking air injection diverter valves and rusted out air injection check pipes and valves will drive these systems crazy..

upstream air is commanded during the first 30 seconds on a cold start until the Oxygen sensor starts switching.. and during open loop heavy throttle operation when the computer does not look at the oxygen sensor readouts for fuel trim adjustments.

if the diverter valve is dumping uncommanded air into the upstream exhaust .. it will fool the ecm into thinking the air fuel ratio is way off and really make the car horrible.  screwed up engine coolant temp sensors also create issues..

in the next day or so.. i will attempt on a E4 tear down for closer inspection and images of the primary jets..

do let me know if you want to borrow or if you want to purchase a 370 kit.. there is another kit that you might also need.. with a pair of tubular tools with hexes in the middle...

looks like the az link also shows oem tool numbers that might help

[Crosley.In.AZ]

do let me know if you want to borrow or if you want to purchase a 370 kit.. there is another kit that you might also need.. with a pair of tubular tools with hexes in the middle...

I may need to take you up on the offer.  My buddy here has not found the carb tools yet.  Says he has them.

The 39mm tube tool, looks like it slides over the smaller tubes in the carb base.  Or do those tubes in the carb body thread out?  i;ve not had time to tear into the carb lately.  Other 'stuff' has my attention in recent days

[wayne petty]

i wish you had replied earlier in the week...

i passed a dozen tool trucks in the last few days.. at least one will have  that tool...  i will get a call around tomorrow.

if i don't end up needing to go somewhere tomorrow.. i may dig into the back of the van where i think the dipstick got lost in....   quite literally a needle in a hay stack..

TIP.[.. 39MM--------0||||5||||10||||15||||20   32nds"

i will get some measurements also..

i might need to stop by the sign shop.. and see if they have some 1/4" plastic.. so i can have them slice it into thin strips to make more dip sticks into. .

[wayne petty]

the autozone site has a great section on adjusting the E4ME and E4MC feedback carbs...

http://www.autozone.com/autozone/repairguides/GM-Caprice-1990-1993-Repair-Guide/CARBURETED-FUEL-SYSTEM/Carburetors/_/P-0900c1528004781a





tool A is in the thexton 370 kit we have been talking about..
but i wonder if the borroughs or kent moore numbers are still available from them ..

tool B is included in a thexton 362 or a thexton 380 tool set..