4350 Rebuild - Ristow

[Ristow]

puttin' a carb together for a pal. thought someone may find it helpful if i showed my work.

4350 motorcraft off a FSJ.

first,remove the top cover screws. 10 of them. they are the larger phillips headed screws. i forgot to snap a pic of the float removal,but pretty simple.pull the pin.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090213.jpg

next,remove the clip from the accelerator pump link,at the throttle arm.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090214.jpg

there is also a clip on the lower choke link,remove it,to remove the link from the lower arm.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090215.jpg

and the top will lift off. this is the underside-what's inside the carb.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090217.jpg

here is the main body with the top off.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090216.jpg

next,remove the 6 screws holding the throttle body to the bottom of the main body.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090218.jpg

and separate them.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090219.jpg


next,we'll move to internal dis-assembly.

[Ristow]

on the internals,first we'll remove the brass plug,shown here near it's bore,it falls out.note there was a small steel ball next to it,look in the above pic,in the main dis-assembly part,and you'll see it.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090221.jpg

next we gently pry the plastic retainer for the needle assy. out to release the needles.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090222.jpg

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090223.jpg

next,the main jets,and needle plunger tube.i used a putty knife as a screwdriver on the tube,it's pretty wide.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090224.jpg

accelerator pump ball retainer and check ball...

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090226.jpg

this is optional to remove.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090225.jpg

next...top cover.

[Ristow]

on the top cover,we remove the large inlet needle seat,and the smaller plug,i do not know it's purpose.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090227.jpg

the accelerator pump plunger,removed by pulling the spring back,and un-hooking from its' arm.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090228.jpg

her's the plunger. note the little pin,used to set the pump stroke,that pin is retained by the collar,slid over it when the desired setting is established.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090229.jpg

gently pry this cover off,exposing the vent baffle.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090230.jpg

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090231.jpg

the pin for the secondary bell-crank is gently pried out.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090232.jpg

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090233.jpg

this should be an E-clip. remove it,and the secondary linkage in freed...

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090234.jpg

..releasing the secondarry plunger from the bottom side..

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090235.jpg

next...throttle body.

[Ristow]

on the bottom plate. the throttle body. remove the 2 idle screws.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090236.jpg

remove the choke arm..

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090237.jpg

releasing the pull-off cam.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090238.jpg

this brass tube will tap out of the choke housing,releasing the fast idle cam.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090239.jpg

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090240.jpg

leaving the 3 main pieces dis-assembled,ready for dip. i like to loosly re-assemble the main parts before dipping in carb cleaner.....

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090242.jpg



TO BE CONTINUED.

[scantar]

Dang, Mike...great pics!

You should do one for a 2150 too...not for me...I'm just asking for a friend. :rolleyes:

[Gambler68]

this needs to be archived pronto!

[mathman]

Nice job. Have a couple of questions/additions:

first,remove the top cover screws. 10 of them. they are the larger phillips headed screws.

Did you find that one of the screws was longer than the rest? When I did mine recently one was longer and it had a regular slot screw head. The instructions with the kit I used indicated that one should be longer (but the same instructions had an incorrect number of screws.)

on the top cover,we remove the large inlet needle seat,and the smaller plug,i do not know it's purpose.

I think it's an extra inlet needle and seat - supplies extra fuel under certain situations if I recall correctly.

gently pry this cover off,exposing the vent baffle.

How necessary is it to remove this? Is it because you dunked it in the carb cleaner? Didn't remove that on mine and wondering if I missed something important.

this brass tube will tap out of the choke housing,releasing the fast idle cam.

The service manual advises to use caution removing and installing that tube as it is easily damaged. When tapping it out/in having a support rod in the middle of the tube will help keep it from collapsing.

Looking forward to seeing the assembly process - be interesting to find out what I screwed up in assembling mine (it's still not quite "right")...

David
'78 J-10
'78 J-20
'50 $WD Pickup

[janie]

Excellent write-up and pic's Mike. This definitely needs to be archived.

[olemisst]

I wish you would have posted this about 4 days ago. I've can already tell I did something wrong.

Do you think if the springs on the Accelarator Pump and Secondary Plunger are switch if it will create a problem? I know one is much beefer than the other.

:banghead:

[Ristow]

I wish you would have posted this about 4 days ago. I've can already tell I did something wrong.

Do you think if the springs on the Accelarator Pump and Secondary Plunger are switch if it will create a problem? I know one is much beefer than the other.

:banghead:

yes,it is a problem. it will give you a weak pump shot on the accelerator pump,and cause your air door on the secondaries to open very late.


mathman,
yes,one longer screw. on that vent,i removed for the carb dip solution. i think i will blank that fitting off,as this carb will be used in a non-emissions application.

[caionneach]

Did you detect any warpage between the upper and bottom halves of the carb once apart?

I have a 4350 to install to my 401, and a search of the 4350 on this site revealed that many have had a problem with the pieces being warped after they were separated. In other words, the carb ran fine but needed a rebuild due to age, and after the rebuild the carburetor was warped and did not perform well with the kind of leakage the warping introduced. Several seemed to have this specific problem.

Kenneth

[fulsizjeep]

I suspect some of the warpage to be caused by over zealous hands twisting body screws too tight or with uneven torque. :rolleyes:

Nice work Mike! :thumbsup:
I agree, this does need to be archived.

[Ristow]

re-assembly begins. there are a few issues i need to deal with before i can fully assemble this,few tattered bolt holes,looks like i don't have the choke pull-off diaphragm,or can't find it anyhow....

but,here is the main assy,from the carb dip.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090243.jpg

we'll start with the lower throttle body. putting both idle jets in,3 turn out from gently bottomed.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090244.jpg

then,the fast idle cam spindle,and cam. put in as shown. tap spindle fully in,from choke cap side.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090245.jpg

then the choke unloader..

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090246.jpg

put the choke actuating arm on,in relation to the cam and unloader,seen behind.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090247.jpg

that takes care of the throttle body for now...

[Ristow]

main body next. first,the needle cluster tube,and main jets. put a new gasket on the tube.no gasket on the main jets.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090249.jpg

install the tube and jets,firmly,but keep in mind these are soft metals.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090250.jpg


next,the needle assy. this o-ring gets replaced. also,see the line on the piston i drew?so i retained factory setting. that is adjustable,for height,with alters when the carb goes to power (rich) mode. those needles replace the power valve enrichment system. low vacuum,the spring pushes the needles up,withdrawing the thick part of the needles from the main jets,reducing flow restriction through them.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090248.jpg

insert the spring and plunger...

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090253.jpg

and install into the body. the needles stick into the holes of the main jets.i have also installed the plastic retainer.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090254.jpg

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090255.jpg

install check ball and ball retainer into the accelerator well.this will be the larger of the 2 steel balls the carb uses.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090256.jpg

that takes care of the main body for now...

[Ristow]

onto the top cover. the air horn.


remove the old umbrella from the accelerator plunger. this one was so hard i needed to cut it off.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090257.jpg

fit the new umbrella,folding it in half as shown,and putting it on the plunger from the side,then rolling it on the rest of the way.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090258.jpg

here the pin is installed,i used the middle hole,and the retaining collar is ready to be slid over it.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090259.jpg

re-assemble the plunger as shown in the dis-assembly pic,compress the spring,and re-install on its' actuator as shown.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090260.jpg

there are 2 inlets,the main needle,and an aux. inlet for high fuel flow situations. this carb had the aux. inlet soldered shut. i'll put the new piece in it's place.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090262.jpg

here is both the smaller,aux. inlet,and the larger,needle valve installed,firmly tightened.the accelerator plunger is to the left,installed. the hole i'm pointing the screwdriver at is the emissions vent i'm going to blank off on this carb.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090263.jpg

install needle and float.at the moment,i don't have the specific float setting,so i'll use the old standby "parallel with the cover upside down" for now.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090264.jpg


next is the secondary air door plunger. take the spring-similar in size to the accelerator pump spring,but much lighter-put the plunger rod through it,then put the rod through the slot in the cover,up towards the top of the carb...

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090265.jpg

install the bellcrank,starting as shown,it fits one way only.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090266.jpg

install the pin,tap into place,then put the link on the door...

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090267.jpg

then put the other end on the bellcrank,and install e-clip.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090268.jpg

getting close to the end now! tha't the primary assembly of the 3 main parts.next we put 'em all together.

TO BE CONTINUED.

[Ristow]

final assembly of the main bodies.

flip the middle,main body upside down.there are raised ridges like shown on 2 of the bolt holes. this ensures alignment of the parts,also ensures the gasket is on correctly,as it fits only one way.i like to grease these gaskets.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090272.jpg

before the bottom plate is installed,i want to point out the 2 vacuum ports.the small orifice the staples are pointing to. both left and right front ports are "ported" vacuum fitting,little to no vacuum at idle,with vacuum coming in after throttle is opened.it's accomplished simply by putting the ports above the throttle blades.as the blades swing up past those ports,the engines vacuum is exposed.remember,vacuum is under the throttle blades.

notice the right,passenger side orifice is positioned a little higher from the throttle blade than the left,drivers side. that means the right side gets a vacuum signal a bit later than the drivers side.that would make the passenger side port the EGR port,and drivers side the ported DISTRIBUTOR port. the distributor gets vacuum before the egr valve.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090273.jpg

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090274.jpg

position the bottom plate over the main body.drop the 6 screws into place,and snug them,progressively.the allen screws are not stock,i got them since this carb had mis-matched screws when i got it.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090275.jpg

flip the carb over. place the small steel ball into shown position. the brass check valve for the accelerator pump is also installed to the right.point down.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090280.jpg

the upper gasket also has the locating bosses,indicated by the orange dowels.put the gasket into position.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090277.jpg

install the float and needle.the nailhead of the floatpin must be on the shown side,or it will slide out in use.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090278.jpg

lower the airhorn into place. you will have the accelerator pump plunger,secondary plunger,float,emulsion tubes....all must be in position,before the top will lower into place. DO NOT FORCE DOWN!

one screw out of the 10 that hold the top on is longer than the rest,it's hole is the one shown by the orange dowel,lower left. all screws will be progressivly snugged down.

http://i50.photobucket.com/albums/f318/milltownmike/carb%20rebuild%204350/P1090279.jpg


after i get the choke pull-off pot for this carb,and do a few things like plug the vent fitting,we'll put all the linkages in place,and do the bench adjustments on the choke.and it'll be ready for service.

[J10Joe]

nice write-up, Mike. This goes straight to my bookmarks.

[Crazy_Jeepman]

nice write-up, Mike. This goes straight to my bookmarks.

If he was not so LAZY!!! I would have had it here this morning. I do have your intake though. I picked it up last night. Joe................he is not really that bad of a guy..............For a Cheese head!! :thumbsup: Though his Garage was a MESS! after he bragged in IRC how clean it was :whistle:

[Ristow]

Though his Garage was a MESS! after he bragged in IRC how clean it was :whistle:


well,there was a wide enough path through the junk for YOU to walk wasn't there?!:lol:

[Dmntxn77]

GREAT write-up!!

[JeepBountyHunter]

:thumbsup: Great...just now noticed your post...this is awesome!

I'll probably print this up with some other stuff I printed over the years.

[J10Joe]

yeah, print away. this is gold

[joe]

Excellent write-up Mike. Very very cool you took the time to document the rebuild...very cool indeed. Thanks.

[Ristow]

lets wrap it up.

first the accelerator pump. note the mounting hole on the throttle shaft,and the upper adjusting nut arrangment.

http://i50.photobucket.com/albums/f318/milltownmike/P1090669.jpg

note the dash and mark that must align when installed.use the nut on the link to adjust.

http://i50.photobucket.com/albums/f318/milltownmike/P1090670.jpg

now onto the choke adjustments.note how the choke pull-off linkage attaches to the carb and pull-off diaphragm. starting with INITIAL CHOKE PLATE CLEARANCE.

with the electric choke cap installed,rotated to the rich (closed) side,open and close the throttle to set the choke.the choke plate will snap shut,and the fast idle cam will be on the top step,meaning,the screw with the spring will be sitting on the biggest step on the black fast idle camas shown. that screw is also what sets the fast idle rpms,which you will do after the carb is on the engine.

http://i50.photobucket.com/albums/f318/milltownmike/P1090672.jpg

hook a vacuum pump to the choke pull-off diaphragm.and apply full vacuum,the diaphagm will pull back,opening the choke a bit as it does..

http://i50.photobucket.com/albums/f318/milltownmike/P1090675.jpg

using a drill bit or allen wrench,and the measurment given in the manual for your vehicle year,measure the choke plate lower edge clearance,between the plate and carb body. use the 1/4" screw on the back of the pull-off diaphragm to adjust this measurment. i used the '75 spec of .166",and used an allen wrench that was close in size.

http://i50.photobucket.com/albums/f318/milltownmike/P1090676.jpg

next,release the vacuum.put the fast idle cam on the second step,up against the shoulder of the high step. measure the choke plate clearance again,as above,but with no vacuum apllied. this is the FAST IDLE CAM ADJUSTMENT. this will be a smaller measurment than the initial clearance.

http://i50.photobucket.com/albums/f318/milltownmike/P1090677.jpg

this is the fast idle cam adjusting screw.this will adjust the choke plate clearance for this setting. again,i used the '75 spec,.147",and a allen wrench that was close in size.
http://i50.photobucket.com/albums/f318/milltownmike/P1090678.jpg

next,open the throttle to set the choke. apply vacuum to simulate a running engine. bump the throttle open and closed.the fast idle cam should go from the top step to the second step.

carb is ready for install and tuning,starting with fast idle speed,regular idle speed,then idle mixture via vacuum guage.

now,if when you are done,the truck starts,then fizzles out and dies,the initial choke clearance is too great,meaning the pull-off diaphragm is pulling the choke plate open too far.use the adjusting screw to remedy it,a little at a time,untill the truck stays running after startup. likewise,if the truck blubbers and chokes on gas after start up,the choke needs to be further opened by the pull-off.

[FSJ Guy]

Even though I have long ago sworn off carbs, this is a GREAT writeup!

GREAT pictures! (I know how hard it is to get good closeup photos. Nice job.)

I think the interior dome light is a nice touch. :)

I hope the Mods STICKY this.

[Wayne]

Nice job :thumbsup:
Better than any manual i've seen.

[trellis8]

Thank you Obi-Wan!