weber question

[CzEcHy]

This is for roodoo mainly, and you testing it on your carb would be great to confirm for me.

I have liquid (in my case carb cleaner), after I pour into the barrals of my weber 38, with the butterflies closed and car off (I was trying to let the cleaner soak at the bottom of the carb), the liquid comes out the primary and secondary throttle shafts. Included is a picture but I pretty much explained it in words. You can see where the cleaner dripped and cleaned the manifold.

Anyway if someone with a weber 38 could pour some carb cleaner to where it pools at the bottom of the carb (above the throttle plates) with the car off, and see if any of it comes back out via the throttle shafts? That would be great.

The manual says there is always a small bit of vac leak from the shafts so I assume liquid coming out would be normal with the car off also since there's no vacum.

Also, that's my linkage setup. No binding, EVER and full travel to WOT. Took me ages to figure it out without the original carb linkage.

[2oodoor]

It's going to do that! Only unless you had a purpose built supercharger carb.

It does tell me you have your throttle stop idle adjustment pretty good and closed at idle.


What idle jet size are you using by the way?

could be optical illusion but your adaptler plate looks warped...

[CzEcHy]

I'm using the stock jets that came with the kit. I'm buying the jet kit in january then getting a new airbox for it then tuned and dyno'd.


And the adapter plate? I may have it on backwards lol, but its packed with rtv gasket sealer so any small warps or potential leaks should be sealed. I overdid the rtv, a lot. Lol


Other than that it idles pretty smooth at 600 or 700 in D4 with slight vibration of entire car but no major fluctuating idle (maybe a 25 +/- rpm bounce) and around 800 perfectly smooth in N or P. Andddd, I can get over 30mpg easily unless I'm driving above 70 for most of my tank lol



Just need to fix the bogging when stomping on the gas from 0mph. Thinking I need a fpr or jets or the accelerator pump is lacking. Dunno

[2oodoor]

I put 60's in mine and made a world of difference, tremendous amount of improvement of idle and tip in throttle response. All vibrations went away.
Air temp has a massive effect on these carbs so when the weather is in between stages like it is now they run erratic unless you step outside and slightly tweek the idle mix screws. Takes only a few seconds to do that.

I bought some 65's and will try those once the temps stay in the 20 degree mornings and 40-58 degrees peek temp afternoons.

If you have a tach you can use under the hood or a camera/mirror to watch your dash tach, you should try adjusting your 2 idle mix screws using that for highest rpm with the throttle stop idle screw backed off much as it will stand it.

If you never have removed your idle jets for anything, it may be a good idea to do that. They are under the brass screw plugs on the sides of the carb. The tinyest bit of debris can cause issues, just take some carb cleaner spray and blow em out.
You can see if your accel pump jet is doing anything by looking down the carb, engine not running, and operate the throttle.. you should get a nice dual squirt the first time.

[CzEcHy]

Ya jet kits are so expencive that's why I don't have one. If you had a spare kit lying around ill take it :p. I'm almost certain all it needs is a slight jet change. Ill check my idle screws in the meantime, where are they located? Can I see one in the picture I posted?

[2oodoor]

Ya jet kits are so expencive that's why I don't have one. If you had a spare kit lying around ill take it :p. I'm almost certain all it needs is a slight jet change. Ill check my idle screws in the meantime, where are they located? Can I see one in the picture I posted?

yeah Im not sure what the 38 come with standard, if it is 50's then absolutely they need to increase.
No, all I see in your pic is the base throttle stop idle screw, just a piece of it anyway.
The idle mixture screws for each venturi are in front and rear. The brass screw plugs are also in front and rear.
You can buy just individual jets, in fact it is probably better to do so since over half the stuff in the "kit" you would not ever use.

[2oodoor]

http://www.carburetion.com/diags/38DGASDiaginfo.asp

diagram of the 38
# 34, 35,and 36 are the idle jets, plug with seal... look on both sides for the same numbers in the diagram.
#87,88 is the idle mix screw, observe the same are in front and rear although the one side parts are not numbered in this diagram, you can see them though.

[CzEcHy]

The rear idle jet isnt behind the choke is it?

[2oodoor]

no but they are a neck stretcher to eyeball

[CzEcHy]

Ill start by cleaning them then order some 60s. Are rear and front the same jet? So I can just order 2 60 jets for a dges ye? Also what's the difference between a large and small idle jet (same website of your post)

[2oodoor]

yes you will need a large and a small 60, wierd is even though there are same size they look totally different than one another on the same carb. check yours first before you order them to confirm that is the case with yours because I think there was a mfg change at some point.

[CzEcHy]

Thanks good info. Ill order those as soon as I can, I take it I shouldn't need any other jets?

[CzEcHy]

My idle jets are 45 LOL. So what size would be good? 55? Or still 60. And yes I have one big and one small.

[2oodoor]

honestly I would go with the 55 first, typically youre supposed to move up in increments of five but I can already tell you 50 would be a waste of effort from what Ive experienced as well as read on the web.

55 ran great on my car but it was cold natured and had an idle I just didnt like because I knew these carbs can purr at unreal low idle rpm with no vibrations 60 cured that on this engine I still would go back with 55 when the days are 100 degrees but never in hell would a 45 do for me lol

[cygnus x-1]

honestly I would go with the 55 first, typically youre supposed to move up in increments of five but I can already tell you 50 would be a waste of effort from what Ive experienced as well as read on the web.

55 ran great on my car but it was cold natured and had an idle I just didnt like because I knew these carbs can purr at unreal low idle rpm with no vibrations 60 cured that on this engine I still would go back with 55 when the days are 100 degrees but never in hell would a 45 do for me lol

I want to say I had either 55s or 57s for the idle jets way back when. It has also been my experience that these engines like a REALLY rich idle, even with fuel injection. 55 would be a good choice. Then tweak the idle screws to get the smoothest idle.

C|

[CzEcHy]

Sounds good guys, I just want this Carb to run perfectly, which it isn't to far from.

Will the idle jet change fix my bogging by chance? If I smash the gas to pull into traffic or w.e, it'll basically stall out then after 2 seconds it'll finally go.. same with in N or P if you rev it fast it bogs horribly.

[cygnus x-1]

Sounds good guys, I just want this Carb to run perfectly, which it isn't to far from.

Will the idle jet change fix my bogging by chance? If I smash the gas to pull into traffic or w.e, it'll basically stall out then after 2 seconds it'll finally go.. same with in N or P if you rev it fast it bogs horribly.

No, not really. It *may* improve slightly since it will be starting off from a better mixture but it sounds like you need a larger pump jet.


C|

[CzEcHy]

Hmm, I wonder what size mine is.. guess I can order a bigger one, going up one or two sizes for the pump jet? What would happen if I went to big? Flooding I assume.

Justlooked, I already have a 70 for the pump jet. can you even go bigger?

K another uodate, took pump jet out and blew into every hole, then adjusted float to I guess max level, and no bogging with a driveway test, let's hope it just had a tiny bit of dirt or something. Lol

[2oodoor]

Cygnus the 55 ran fine on the stock A20 but on the B20 it was very finickey with cooler outside temps. Always having to tweak the mixture on days with broad temp differences from morning to quittin time. lol
I think a 57 would be interesting, it didnt have those nor were any in the pack.
Czechy I agree about the accel pump jet, there is a number stamped in that.
I forgot what was in mine. I think 70/// Cleaning it out definatley may help as well as cleaning out the port in the carb it pulls from.
there should be no bog at all on any weber, every one Ive used would break the tires from a stand still no matter the engine. The idle mix adjustment makes a good difference so if you can do the best idle procedure weber publishes it works. I helped me to use a digital tach under the hood because the tune by ear can get aggrivating if you're distracted.

[CzEcHy]

Ya mine was a 70, I cleaned it and raised the float, the bog seemed like it was gone. tuning the idle jets should bring it to 100% no bog, although I'm pretty sure its gone. It must of just been dirty because it used to peel out from a dead stop then one day it started the bogging. Guess it must of just been dirty and cleaning it today must of worked. Can't wait for a road test to confirm it.

So I after I get the idle jets bigger, my weber should be near perfect.

[CzEcHy]

Still has a bog.. would it be my fuel pressure? Maybe the float is to high?

Like I said, I have the biggest pump jet, its a 70.


http://www.mossmotors.com/forum/forums/thread/4190.aspx

Read post 4101, its the 3rd or fourth down.. what is the power valve, couldn't figure out where it was at on that website diagram you posted Guy.

[2oodoor]

it's inside the bowl, I don;t think that is your issue but who knows...

70 is plenty on the pump jet, but im curious does it do this bog even after the car is well warmed up or does anything change at all?
Next time you have the tophat off, get some good throttle body or carb spray with the little straw on it and just shoot it in every orifice you see, and it is a good idea too to do this while youre idle jets are out in that hole as well.
Another thing to spray too is take the adjusting screws all the way out and spray some in there. Count the turns on those so yeah you will have to adjust those over again anyway.
Only other thing to check is ignition timing if it is a long long bog or lull before it gets some rpm.

[CzEcHy]

I always warm my car to full operating temp, winter or summer, before I drive.

I'm ordering the 55s tonight, but I sprayed EVERY hole inside the Carb. Took the top hat off and drained the float and wiped it out incase sand got in or w.e, sprayed everything, got Carb cleaner in my eyes, ran to sink, then continued on the Carb.

When I get the new jets if it still bogs ill call redline and ask their advice.

[2oodoor]

so you are getting a good squirt of gas on both sides of the pump jet I guess? engine off, look inside down throat, pull on the throttle.

[CzEcHy]

Ya, powerful streams straight down into the manifold.

Tried keeping revs at 1700ish RPM while holding the brake ( in drive), and it bogged when I smashed the gas pedal still. So it had air and fuel and still bogged. Any more ideas? Lol