38 weber Q&A

[zigzag]

ive contacted Roodoo2 and 2ndGenGuy with questions concerning the weber 38 and its installation both under the hood and locations for the choke knob and how to run it. 2ndGenGuy suggested i open a new thread to get collective ideas from the members of the forum, so here i go. i also have pics i will post.

1st-
how would you go about running the choke cable from the carb to the dashboard, and which spot on the dashboard would you use? how do you hook the cable to the carb? also in the blue circle is that for a vacuum line?

http://img6.imageshack.us/img6/7383/pict0666xi9.th.jpg (http://img6.imageshack.us/my.php?image=pict0666xi9.jpg)

2nd-
there are 2 fuel inlets going into the carb.. you plug one off, but which one? will post pic....

http://img17.imageshack.us/img17/4600/pict0663kn4.th.jpg (http://img17.imageshack.us/my.php?image=pict0663kn4.jpg)

3rd-
vacuum lines.... from my understanding Roodoo2 told me there should only be one vacuum line for the vacuum advance.... which im assuming is the one behind the linkage.... and which ever hose is connected to the carb should go in that spot.... vacuum hose #2.. (on a side note my vacuum advance distributer snapped off the distributer cap, but it still works.... should i get a new one asap? i read somewhere unplugging vacuum line #25 connected to the vacuum advance could cause knocking in some motors, could it be the bearing noise i hear?)

also the arrows pointing to the holes.... are they for anything? it doesn't appear like they go anywhere, but it doesn't hurt to ask.

http://img17.imageshack.us/img17/4816/pict0664bb6.jpg

4th-
tuning.... how would you go about tuning the carb? air intake and fuel intake knobs, or anythig else that should be tuned.. it is bran new never been used so should it come pretuned? this is what i need most help with.

5th-
ive read that i should use gasket sealer between the plates, and that you shouldn't cause it might cause a leak later.... what is your take on this?

that pretty much covers it.... for the questions unless anyone else has any questions they might want to add to the list. hopefully this thread will be helpful for others looking for answers as well.

[2oodoor]

Like I suggested in the pm, you need to get used to taking the top off the carb. You need to find out what main jets, emulsion tubes, accel pump jet, and air correctors you have in it.
It may run fine just like it is, but you will need a starting point for anything otherwise, which would be recording sizes of those items.
You can pull the idle jets without taking the top off, they are the two brass screw plugs on either side of the carb.

Base tuning, start off with the main throttle stop screw backed out all the way and both idle air adj screws about one full turn out from bottoming out. Warning, never bottom out those screws with a screwdriver you will damage the needle tips, do it very gentley.
See if the car will run and idle like that, you wil need to gradually turn in the throttle stop screw little at a time to get it to stay running possibly.
Further adjustment procedure is on the redline weber website and this thread
http://www.3geez.com/forum/showthread.php?t=4223

If you can get a close up pic of the sides I can tell you if you can use an electric choke. I dont see why you couldn't. It would make things easy.

When you get a rebuild kit for these all that is in there is base gasket,accel pump, power valve pump, and top hat gaskets. That should give you an idea of how simple these carbs are constructed. Some of us are having some leak issues with these 38, I fixed mine by using two top hat gaskets together. there is a place between the float bowl and venturi where gas can pass thru unmetered, the gasket takes care of that.

The choke plate is not supposed to move unless the throttle is opened up first, then it pulls up rod that boosts up the idle speed once you release the throttle. So as you connect the choke, you may want to have something holding the throttle open while you are working with it. (not running of course) It is just a basic open and close thing as far as adjusting it, You want little travel as possible in the cable once you have it mounted up. No binding at all or it will give you problems. I would do the electric choke though, as long as the carb body has a place for it to go. I have some extras I would let you get possibly.

[zigzag]

which side do you need a close up of? ill have to get it done after work i leave soon....

what do you mean by turning the idle screws one turn before bottoming out? it looks like it came with the screws as far out as they can go without hitting the bent tips, and the main throttle stop screw backed out just about all the way.

[cygnus x-1]

You don't need any of the vacuum ports on the carb. Just plug them. The distributor vacuum advance port should just be connected to any vacuum port on the manifold; doesn't matter which one.

You can run without vacuum advance at all but fuel mileage will be not so great and throttle response will be sluggish.

C|

[2ndGenGuy]

About those two fuel inlets, I'm not 100% sure what you're really supposed to do, but I just wound up capping the top one off and using the lower one for fuel supply.

Unfortunately on the manual choke Weber 38s, you can't convert them to automatic choke with a kit. At least that's what I was told by Carbs Unlimited.

I hear there are choke cable kits you can buy at the auto parts store, they're kind of a universal kit. Then you'd run it through a grommet in your firewall, and drill a hole in one of those blockoff plates in your dash where the switches go.

I've gone both ways with the gasket sealer. I actually have it on my 81 Accord. I couldn't get the adapter plates to seal at all, and spent hours screwing around with it. I finally decided to try the gasket sealer and it worked fine. On my 84 Accord, I've swapped at least 4 or 5 different carbs on it, and had no need to put any gasket sealer on the adapter plates or carb base. I'd say if you can get away with not using any, you're better off. I also had to redrill the bolt holes on the 81, which leads me to belive that the quality wasn't all that great. So if you get good plates, I don't think you'll need to use gasket sealer.

As far as jetting and tuning. Like roodoo said, take a look at what jets you have in the carb. Also, there is a thread with whole bunch of people with their jet sizes posted. You could use some of those as starting points. Try to find the setup closest to yours and go from there. I dunno if you've ordered jets already or not, but you might want to order a nice assortment, a few sizes bigger and a few sizes smaller. This will let you test out and see how it goes.

[mephi]

I'm installing my Weber tomorrow. As far as the fuel input goes, mine only has the bottom one, so I guess just cap off the top.

As far as jets, I'm going to try this and the see what needs to be changed:

1.50 Mains
0.45 Idle
2.10 Air Correction
0.70 Pump Jet
F50 Emulsion Tubes

The pump jet is a little large, and I think the mains might be too. You can actually get to both the idle and the air correction jets without removing the top hat, at least on mine. everything else just take a screw driver and undo those screws. Really easy.

[turabaka]

manual choke is pretty easy to setup on these. I got tired of trying to get the damned electric choke to work perfectly so I just converted to manual. Ended up routing it though the firewall and mounting it on the dash in one of those blank inserts for where add on accessories go to the left of the steering wheel.

[zigzag]

manual choke is pretty easy to setup on these. I got tired of trying to get the damned electric choke to work perfectly so I just converted to manual. Ended up routing it though the firewall and mounting it on the dash in one of those blank inserts for where add on accessories go to the left of the steering wheel.

all of them are used up lol.... was thinking about drilling a spot to the right of it though....

[mephi]

Agh...Not doing it this weekend after all. Head I was going to replace mine with is warped...Now I have to take it to the machine shop. :crying:

[zigzag]

that sucks man i hope they fix it right for ya.

i need to see if i can modify the old air intake to fit the top of the carb.... im sure i could.

[2oodoor]

I do not recommend rtv silcone type gasket sealer around the carb base!

I used permatex high tack only as an adhesive coat with very little builder but some builder . worked great for me.
Be careful with the studs on those, you can actually screw the stud in when you are turning the nut. .
Watch that the stud does not turn with the nut, because if it does you are pushing the plates apart, distorting them.

Yes I forgot about the vac adance being on all the time on these cars. so Cygnus thanks for the correction. Side note, I read that you can use both advance ported and venturied ..no need to really imo.

YOu should be able to use choke parts from a 32/36, not absoluley sure.

Be sure to plug off the small coolant passage under the base of the carb, you will have problems if you dont. SOme have used JB weld, but the last one I did I threaded the hole and used a set screw that size.

Throttle return springs, none of the provided ones seem to cut it from what I have seen and read here. I used universal springs from parts house and got creative for location of the spring.

[zigzag]

what exactly is the vacuum advance for? mine snapped off the distributor cap.

[88Accord-DX]

I don't know why some people get so paranoid about using a little high temperature RTV between two plates for a carburetor adapter. Come on, this isn't rocket science. I used a little to between the plates so not to leak & guess what, it works fine.

The bolts that need to be pulled on the carb, spray some PB Blaster on them & let them soak for an hour or so. They don't come out easy & can break off easy. It happened to me & had to drill & heli-coil one.

The vacuum advance is supposed to keep the motor from knocking & advances the timing under load. (theoretically)

Here is a pic of the vacuum lines to back of the intake manifold off the distributor.

http://www.3geez.com/forum/attachment.php?attachmentid=3655

[cygnus x-1]

what exactly is the vacuum advance for? mine snapped off the distributor cap.

It changes the ignition timing based on the amount of pressure (or vacuum depending on what you use for a reference) in the intake manifold. Manifold pressure is a direct indicator of how much load is on the engine, and therefore how much fuel it's using. Depending on the amount of air/fuel coming into the cylinders, the point in the crank cycle where the spark plugs need to fire changes because the combustion rate of the mixture changes. Less dense mixtures (light throttle low load) burn slower so the plugs need to fire sooner for optimum torque transfer to the crank. More dense mixtures burn faster so the plugs then fire later.

Without vacuum advance the plugs won't be firing soon enough for optimum efficiency under low loads. This also leads to higher exhaust temperatures and higher NOx emissions. At full throttle there is no vacuum, hence no vacuum advance. So it won't have any effect there.

C|

[zigzag]

so are there any vacuum lines attaching to the carb? or do i plug them off? there seems to be 2, i circled them in blue.... i also looked at the fuel inlets and the bottom one is open while the top one has a pin point hole, so that makes the decision of which to plug off quite easy.

[2oodoor]

I don't know why some people get so paranoid about using a little high temperature RTV between two plates for a carburetor adapter. Come on, this isn't rocket science. I used a little to between the plates so not to leak & guess what, it works fine.

The bolts that need to be pulled on the carb, spray some PB Blaster on them & let them soak for an hour or so. They don't come out easy & can break off easy. It happened to me & had to drill & heli-coil one.

The vacuum advance is supposed to keep the motor from knocking & advances the timing under load. (theoretically)

Here is a pic of the vacuum lines to back of the intake manifold off the distributor.

]

because that nasty stuff gets everywhere, even when you can't see it
all it takes is a micron of that sh*t to get in the air bleed past the idle air needle and you can possibly ruin the carb if you can't get it out. I dont think you need any of it in the CC or cylinder either. There are just too many other products you can use without those worries.
If you want to seal a throttle body, probably not as critical so there is not a comparison.
rtv doesnt like being soaked in fuel either, and the weber can get a little wet at times.
I dont care which rtv product you are talking about, it is still silicone, and you dont need that big of a solid base product for this. Yes you can spred it thin but it does not bind as well then either and will be more subject breakdown and moving.

[mephi]

So not even gasket tack or something like that? I've always liked using that high tack gasket sealant from Permatec or whatever on my paper gaskets before install, but then again, I never used it anywhere near a carb before.

[88Accord-DX]

because that nasty stuff gets everywhere, even when you can't see it
all it takes is a micron of that sh*t to get in the air bleed past the idle air needle and you can possibly ruin the carb if you can't get it out. I dont think you need any of it in the CC or cylinder either. There are just too many other products you can use without those worries.
If you want to seal a throttle body, probably not as critical so there is not a comparison.
rtv doesnt like being soaked in fuel either, and the weber can get a little wet at times.
I dont care which rtv product you are talking about, it is still silicone, and you dont need that big of a solid base product for this. Yes you can spred it thin but it does not bind as well then either and will be more subject breakdown and moving.
That is true to some extent if your making a peanut butter & jelly sandwich out of it with the carburetor adapters.:tongue: Plus the adapter sets below the air jets and all, it not like it's above the venturi or nothing.
You must of had some bad results or something with them old Holley 4 barrels & Edelbroks back in the day. Anyhow, I used the red high temp. stuff rated like 1800 degrees & it hardened pretty hard. Hell, the plates are so tight you don't need but a thin layer on the outside edges of the plate. Sure, if anyone is not sure what there abilities are, don't mess the RTV then.

[zigzag]

hey lucky day.. seems every time i try to log on to this forum i come across a database error....

alright so i got the vacuum advance on and it seems to idle much more smoothly.... plus some of the bearing noise has gone away.. but not completely.. still trying to find someone to help me put this new 38 in.. got everything for it except the huge spring.. question: how does that spring hook up? from the linkage to where? and whats the purpose of it?

also i want to keep the vacuum advance on the car after i install the the new carb.. where exactly would i hook those 2 vacuum lines to since all the vacuum lines will be stripped out apparently.... and what vacuum lines or ports do i plug....

about all the questions i have....

[mephi]

got the vacuum advance on and it seems to idle much more smoothly.... plus some of the bearing noise has gone away.. but not completely.. still trying to find someone to help me put this new 38 in.. got everything for it except the huge spring.. question: how does that spring hook up? from the linkage to where? and whats the purpose of it?

also i want to keep the vacuum advance on the car after i install the the new carb.. where exactly would i hook those 2 vacuum lines to since all the vacuum lines will be stripped out apparently.... and what vacuum lines or ports do i plug....

I got mine installed 2 weeks ago. Runs WAY better than the stock one. For the return spring, I just stretched it between the forward throttle gear arm thing and the lift hook point on the engine. It's not pretty, but it works.

As for the vacuum lines for the advance, you should be able to salvage one of the vacuum trees from the original vacuum set up and just plug it into one of the vacuum ports on the top of the manifold. That should give you more than enough vacuum ports to use for whatever you need vacuum for. I'm going to use that for the charcoal canister too, when I actually get around to hooking it up properly.

[2oodoor]

yes hi tack is what i use as well for that, BRUSH IN CAN type.

[zigzag]

you think you could get a close up pic of the spring so i could see how exactly it all hooks up?

the vacuum tree sounds like a good idea.. so anything else that had a vacuum line hooked up to it needs to be plugged up.... what about the a/c? would it still work?

[mephi]

I don't believe you would have a/c idle adjustment. A/C will still work, but it might kill your car at idle. Not really sure about that, I don't have A/C. Do a search and see if anyone else has figured that one out yet.

I'll post a pic of my setup in a little bit. I have some work to do first.

[mephi]

It's far from pretty, but here you go.

http://i288.photobucket.com/albums/ll171/luke_kl/03-24-09_2319.jpg

From the front. I need to fabricate some sort of bracket for the fuel line

http://i288.photobucket.com/albums/ll171/luke_kl/03-24-09_2320.jpg

The linkage isn't perfect, and I'm sure there is probably something wrong, but it seems to work so far. The spring in the back came from a Land Cruiser conversion kit. The carb was on a 75 land cruiser 4 years ago. Then it sat on a shelf until I found it. Manual choke is about halfway installed.

http://i288.photobucket.com/albums/ll171/luke_kl/03-24-09_2321-1.jpg

I wanted to finish my linkage before I posted any pics...Now I can actually go WOT. I used the brackets out of the black box for material.

*EDIT* I would suggest against routing the spring this way...It don't work well!!!

[Civic Accord Honda]

mmmm weber sexiness

[2oodoor]

http://i162.photobucket.com/albums/t280/roodoo2/1212440978.jpg

[mephi]

Ya...mount your spring like roodoo2...down and towards the back. Works way better that way!

[MessyHonda]

i always wanted a weber...damn cali smog

[zigzag]

so what exactly is the spring for?.... i notice the idle adjustment screw on the linkage.... but the other two on the side at the base of the carb.. what are those for? i notice they have a bent needle point but they dont seem to do anything or block anything when i turn them.... kind of confusing....

[2oodoor]

so what exactly is the spring for?.... i notice the idle adjustment screw on the linkage.... but the other two on the side at the base of the carb.. what are those for? i notice they have a bent needle point but they dont seem to do anything or block anything when i turn them.... kind of confusing....

bent needle point? they are ruined if that is the case...
you have the carb on the car and running?

[zigzag]

no its sitting next to me.... its just the tip thats a little bent.. it came that way.... ill take a pic and upload it.... cant find anyone with the tools to help me install it.... starting to piss me off cause i have nothing to cut into the intake manifold.

[zigzag]

http://img257.imageshack.us/img257/3259/pict2160.th.jpg (http://img257.imageshack.us/my.php?image=pict2160.jpg)

here it is the two bottom screws.... i still dont know how they function.... its a rather large picture with good detail....

[mephi]

I think that is bad. You may need to replace those.

In order to modify the manifold, I just used a dremel and a drill with a rotary file bit. You can get the file bit at your local hardware store. It took forever. I still have a pile of aluminum shavings on the floor. Oh, wear a mask...I hear that stuff is bad for you.

[lostforawhile]

I think that is bad. You may need to replace those.

In order to modify the manifold, I just used a dremel and a drill with a rotary file bit. You can get the file bit at your local hardware store. It took forever. I still have a pile of aluminum shavings on the floor. Oh, wear a mask...I hear that stuff is bad for you.
it is? whoops.

[2oodoor]

those needles dont even look like the right ones, but being bent means they will never be able to meter properly AND if you force them in the hole it will waller out the carb housing too, thus ruining it .

[cygnus x-1]

As long as it's only the tip of the needles that's bent you could chop or grind those off. Screw them in all the way so they seat and just snip off the bent part with a diagonal cutter. Then knock off any burs with a fine file or stone. As long as the needles seat properly they should be fine.

C|

[zigzag]

but i mean they do nothing.. they block nothing.. they just sit there.... couldnt i just take some needle nose pliers and bend them strait? do they really look that bad? and what do you mean they dont look like the right ones?

[2oodoor]

but i mean they do nothing.. they block nothing.. they just sit there.... couldnt i just take some needle nose pliers and bend them strait? do they really look that bad? and what do you mean they dont look like the right ones?

they do plenty, they meter the amount of air going in the mixture as the throttle is closed. thus being your idle air control metering.
Is the carb on the car yet?

[zigzag]

no i have no one to help me put it on.... not to mention no time to put it on when i consistently work and all.... why you need something? more pics or something....

[cygnus x-1]

but i mean they do nothing.. they block nothing.. they just sit there.... couldnt i just take some needle nose pliers and bend them strait? do they really look that bad? and what do you mean they dont look like the right ones?


They look a little long maybe but that won't hurt anything. As long as it's only the part sticking out of the hole that's bent they are probably fine. You could bend them back or cut the tip off. With the right jetting the needle adjustment range will only be about 1 turn out from all the way in.

C|

[2oodoor]

Do not take them out if they are bent too bad. they will damage the carb. Depending on which end is bent and how bad. I would just leave them alone, not file or cut them, that risks damage if not done meticulously. YOu need to get it on the car to see where you are at with them anyway.

[zigzag]

theres no electronics hooked up to it.. how do they work? they aren't as bad as the pic depicts.... but what difference does it make whether they are bent or strait? as long as its protruding out it should do its job right? just got to remember not to unscrew them too far while its on the car.

also i am tired of these damn drum brakes.. is there any way i can convert them to rear disk brakes? im sure there is.... i hope there is....