Tuning a Weber 32/36

[Spades]

well, I bought a new weber 32/36 from webercarbsdirect for my naps z20s, and it works fine except for one issue...if you stab the throttle, there is a lean spot before the secondary dumps fuel in. if you go very slowly into the throttle at any RPM, it will perform well without a lean bog.

 

I want to get rid of that lean sag, and I am wondering if I need to re-jet the primary.

 

some history on the motor the weber is bolted to:

 

its a naps-z20s, rebuilt with about 50 miles on it, head work was done at the same time. its running without the EGR system, a new fuel pump, electronic distributor, a flamethrower coil and NGK 8mm plug wires and platinum plugs, and is running through a 27" glasspack with side dump exhaust.

 

if you stab the throttle, it goes to a lean sag, then after about a second, the fuel from the secondary kicks in, it will run smooth till redline. It was running rich under load, so I had timing advanced, but I notched out the arm going to the mechanical secondary, so now my plugs arent getting fouled and i was able to back the timing off a couple degrees.

 

so, to get rid of that lean sag, am I looking at rejetting? or does anyone else ever have this problem? is there something wrong with my carb or is the lean sag common with a 32/36?

[SRSANDS]

I know very little about carbs or L motors(had a bad valve and didnt know it :))...but I had a weber 32/36 on my L16. It had a bog right in the middle before the secondary also. If I gently pushed the gas it was good and it ran like a rapped ape. Hainz helped me and pointed out that my install may have been the problem. I had the thing torqued on too tight and I didnt cinch it down while using the cable wheel to hold the butterflies open while doing so and that caused it to do that.....try that.

[bonvo]

thats just the nature of the beast the accel pump just cant keep up when you open the secondary

[MAG58]

Yep, most webers do have a little lag when the secondary flips open. Some really creative jetting can assist the situation, but I finally ended up drillng out (by no more than a few thou) the accel jet hat that sits above the venturis which corrected the issue, more or less. Supposedly Weber used to make different jets for the DGV's but I could never find the different squirters so I got creative.

[datsunfish]

I really never understood the whole bogging issue. I have used a ton of 32 36 webers and most of them never bogged but they were always on L motors and a vw and amc jeep cherokee once too. Its usually a non carb related issue such as a vacuum leak or timing. Or you are expecting it to burn rubber when you drop the pedal. Theres not enough torque there for that.

Does it bog out from an idle when you stab it and are parked out of gear?

[banzai510(hainz)]

if you punch it too quickly it will bog. best to give it a nice slow puch and it will transistion better.

 

one thing about stock carb is the vacuum 2ndaries are very smooth

[SHADY280]

mine does the same, i have an L16. just one of those things i guess. that why the R1 carbs are so attractive to me.

[Spades]

ok, so, i have had several people look at the car to make sure i am set up right(one benefit of working at a automotive repair shop), and also one of my dads friends who has had over 20 years experience with nissans and datsuns.

 

my timing is spot on, no vacuum leaks, and the hesitation is dumping the throttle below 3k+ rpm. if you use a very light foot, it will not hesitate, but if the throttle is punched hard at lower RPM, there is a second of lean bog. and yes, it bogs when it isnt under any load. pop the throttle in neutral or under load, it does the same thing. when the secondaries finally dump fuel a second later, the engine slowly picks up and starts screaming.

 

i will try loosening the carb, then keeping the throttle open and re-tightening as srsands suggested.

 

if that doesnt fix my problem, are there tricked out accelerator pumps or different primaries i can get for the 32/36? i was thinking about using this carb if i add a turbo, but i have to sort the lean thing out first....

[banzai510(hainz)]

is this Napz a 4 plug or 8 plug?

 

Most webers I have ever put on run pretty dam good used or from the box.

 

yes you can get different jets. but I dont think thats going to matter to much.

remember the 2nd barrel dont have a accell pump so there is going to be abit of a bog. If anything people put in smaller main jets on the 2ndaries

 

if in dought go back to your 1st statment:He should know.

ok, so, i have had several people look at the car to make sure i am set up right(one benefit of working at a automotive repair shop), and also one of my dads friends who has had over 20 years experience with nissans and datsuns.

[Spades]

4 plug naps z20s. My dads friend checked and my timing is right, I have no vacuum leaks, and valves are adjusted right...he mentioned that since it didnt have a accel pump on the secondaries that was prolly what was causing it...he noticed on the side there was a opening where a secondary accel pump could possibly go, but it has a small weber sticker stuck over it that says "warranty void if removed".

 

he said he was going to poke around and see if he could find a way to make the carb function better, and thats where we left off last night. I figured I would ask here and see what other people had come across with the 32/36.

 

it runs great other than the seconds bog when you step on the throttle hard...and no one i have had look at it can find any problem other than a lean spike from the carb when the throttle is jabbed.

 

EDIT: on my lunch break, I pulled the 32/36 off, used gaskacinch on the upper gasket, then evenly torqued the nuts down lightly while holding the throttle open. at low RPM, i still have a lean spot that goes into a rich spot and stays rich and sputters until the throttle is let off. but now, if the engine is over 1k RPM, I can punch the throttle, and the lean spot isnt as bad, and if i dump the throttle above 3k RPM, it takes off and pulls hard untill i shift, with no bog at all. i think i need to advance my timing a small bit to adjust for the current rich condition. so right now, its a slight lean spot if punched at low RPM, then it barfs fuel in and goes rich...almost like the secondaries are too much and the primaries are too small...anyone have any thoughts?

Edited November 4, 2009 by Spades

[newguy]

boy I'm right with ya, I have the same problem.

[yello620]

Post up what your jets are right now. I want to know all of them too.

 

Primary/Secondary

Idle jets

Main jets

Air bleed jets

Emulsion tubes

Accelerator pump jet

[Spades]

I will see if I can pull up jet information, lemme go hunt for it!

 

I think the paper for the carb is at work. this is the link to the carb and the sight I bought it from.

 

http://www.webercarbsdirect.com/32_36_DGV_p/22680.005.htm

 

it is stock and I have not changed any jets or anything yet.

Edited November 5, 2009 by Spades

[Spades]

I am still messing with the timing, i advanced it a few degrees because since the torquing down the carb with the butterflies open, its running pretty rich again. I am maybe 1 degree too advanced at the moment, but I am getting closer.

 

as it sits right now, if the RPM's are higher, no stalling or stumbling, however, if you stab the throttle wide open under 1,000rpm...the engine hits a lean spot for a second, then goes super rich and pulls out of it. it basically is acting like a poorly tuned quadrajet :D

 

I do have a solution though, get the timing set and run it as is for now, and put the header for the z24 on the z20s, and prep the z24 and build a manifold for a small turbo, then run about 5 PSI through a good intercooler with the weber on the z24...get a bigger primary jet on the 32/36, and the turbo will put my mixture right about where it should be :D

[yello620]

Have you read the weber tuning information on the racetep.com website? Also need to verify that the jets in the carb are what the kit is supposed to have. That carb kit is supposed to have a 140 main jet, i have found that to be too small on my L20. And the 165 air bleed could be a little bigger to help with the rich toward the top of the primary.

[fo0manchu]

do you have a vacuum advanced distributor? are you running mechanical fuel pump or electric?

[Spades]

its a new electronic distributor with vacuum advance, and the vacuum advance is functioning properly. it is a mechanical fuel pump, and im getting the right pressure to it, and it is steady pressure, not putting too much or too little flow. from testing it and driving it, I dont think it is ignition or fuel pump related, i think its that my secondary is too much and primary is too little.

 

i would agree that the primary is too small of a jet, it runs lean untill the secondaries open. after messing with the timing, I have it to where now at higher RPM when you stab the throttle, there is almost no lean sag, but there is a little rich bog the lower the RPM's are. at lower RPM under partial throttle where the secondaries arent opened, it runs lean.

 

I am thinking I might change the primary jet, because the issue I have, is that I have to keep timing backed off enough that it runs properly at idle and low RPM without a load, but advanced enough to cope with the large amount of fuel dumped in when you give it full throttle.

 

unfortunately, there isnt much that can be "tuned" on my distributor, you cant change the timing curves, it just has what you set it at, and then what the vacuum advance sets it to, which is non adjustabe as well.

 

so, at the current moment, im running lean untill the secandaries open, then it runs rich. my logic is, maybe i can get a larger primary jet, and then put a small intercooled turbo with under 5psi on it to adjust for the slight rich condition. thoughts?

Edited November 5, 2009 by Spades

[sly-yota]

im having the same issue with my toyota 20R hybrid right now, im about to just throw the stock carb back on and ditch the pos weber, i havent had one run right yet. :mad:

 

my other issue im having with this carb is i can turn the A/F mixure screw all the way in and it stays running, even though every single gasket on the engine is brand new less than 200 miles on it now, timing is spot on, and when i brake hard it drops the idle and stalls out, when its normal at idle it idles around 1k-1200 and the truck has no power and wont stay running unless i sit and feather the throttle for about 5 min untill its at running temps. so im completely lost..i think the carb has to be bad and need rebuilt as it was used when i got it but it looked to be in really good shape, clean inside and out.

 

anyone have any clues as to whats going on? (not trying to hijack your thread, maybe this could help both of us.) Btw if your bog is going lean, someone said above to slightly drill out your jets, how well did that work? and also what did that do to your gas millage since we all know the weber drinks like a fish.:blink:

[sdsurf]

Man I am having the same problems. So far I reamed the jet out a little and that seems to help. I got caught working on another project so I stopped messing with it. I am glad this is being addressed and I will follow closely.

[Spades]

I found out something very interesting tonight. I had been messing with the timing at lunch today, and just couldnt get it to behave at idle and wide open throttle...so tonight i hooked up the vacuum gauge again.

 

if you are running your vacuum advance off the bottom of the 32/36 like i was, attempting to keep the charcoal cannister and everything hooked up the way it was with the hitachi carb, check the vacuum comming from the base of the carb.

 

I hooked a vacuum gauge up and watched it...on my carb, I have no vacuum at idle, then if you stab the throttle, it puts vacuum through...and the weird thing is, you can hit the throttle the same way 5 times, and each time it gives a differant vacuum. it would vary from 0-25 inches, and it was never consistent at all!

 

maybe my understanding is wrong, but isnt there supposed to be more advanced timing at lower RPM for idle and hiway cruising to give a more complete burn and keep the plugs clean, then when you go wide open throttle, go with more retarded timing...so technically, if my logic is correct, the ported vacuum from the carb is doing the exact opposite. whats more, the vacuum from the carb is so inconsistent, there is no way to set timing at all, which explains a good portion of my problems.

 

with my distributor, vacuum advances the timing, so if my logic is correct, i need to plug my distributor straight into the manifold vacuum, and then back my timing off again.

 

 

P.S. i drove it home tonight without any vacuum advance, and set the base timing very advanced. it doesnt have very much power, but it started, idled, and ran quite well, and i have no bog or any other weird symptoms anymore. I still have a slight lean bog, but it is only a fraction of a second, and then it rails great till redline. tomarrow I am going to run the vacuum advance straight to the manifold vacuum, and retard the timing and see what kind of power and drivability i get.

[fo0manchu]

thats weird.

I know when i was tuning the carbs, i had the vacuum advance hooked up to the manifold and that was causing bogging. When I hooked it up to the base of the carb that fixed the problem. but then again this is on a bmw 2002 engine. So it might be different with the l20's

 

I vacuum line on the carb is suppose to decrease the vacuum pressure as compared to a vacuum source on the manifold. I believe the readings should be consistent though. I'll check mine.

 

Your right about the vacuum advance. Idle=more advanced timing, wot=more towards base timing.

 

Also, under 3000rpm's your carbs are running solely off of your idle circuit which just consist of your idle jets.

 

the carb is pretty sensitive to everything. even the smallest vacuum leaks. It took some time getting it setup right, but once its done it runs great. I ended up taking mine completely apart and spraying every orifice out with carb cleaner and cleaning out all the filters and replacing the gaskets. I actually found one gasket that was missing. It was a little o ring. I couldn't even here that vacuum leak. On top of that, crud from the fuel lines had clogged up the screen filter in the carb as well. All it takes is a little piece of dirt to clog those little holes in the carb. neadless to say, when everything was put back together it ran great.

 

I just read this article online and it says to rev the motor and then slap your hand over the carb. This is suppose to create a big vacuum and suck any dirt or debri out of the vacuum holes. I haven't tried it, but maybe it will work? Try at own risk. :D

[banzai510(hainz)]

the base should hook up to the vacuum adv.

however I dont know the newer car execpt that they have so much emission stuff that if could affect it.

 

persoanlly I dont think anything is wrong with the carb. I have run a Weber outlaw 38DGES double opener on a L16 and it ran fine and it was way over jetted but stull ran fine.

[Spades]

its not just the carb, i did some reading last night and found that alot of early 80s engines did not have good ported vacuum design, as it was a add on to help the car get better emissions.

 

so, it might be more than just the weber. I do know that after playing with a vacuum gauge last night, the weber pulls 0 inches of vacuum at idle. when you stab the throttle vacuum goes up....the exact opposite of what you would want to happen...whats more, the vacuum is the same as my manifold vacuum, it goes up to 23 inches...however, the carb will pull a different amount of vacuum every time you tap the throttle, which is why I couldnt get the timing perfect, and explained alot of my problems.

 

after re-routing vacuum lines and tuning this morning, I was able to get it to run and idle great, accelerate good, and run smooth. the timing still needs adjustment I am sure, because I was tuning it by ear and didnt have a timing light with me.

 

the only thing left now is the lean sag when the throttle is stabbed quickly. I cant adjust the timing any further to compensate for the lean condition without going too far advanced.

 

at this point, I think its time to look at a bigger primary jet, and all my problems should be solved.

 

p.s. the weber 38 wouldnt have as many problems as the 32/36. according to weber the 38 is designed for race applications, and while it may be overjetted for small engines, weber recommends it for better low RPM throttle response, and says that the 32/36 is for smaller engines and street applications. basically, the primary is too small, and is designed for better fuel economy, and the carb was designed for slow,smooth passing power. and as far as the ported vacuum at the base of the carb, it may not just be the webers design, it could be a flaw with the design of my cars intake manifold...whats more, the adapter kit used to mount the carb spaces it over 1 inch above the manifold, that could be contributing.

[Spades]

Ok, grabbed a timing light and set timing today. If the timing marks are right, I am between 11 and 12 degrees. stock setting with EGR and factory carb and ignition system is 8 degrees.

 

between the mods and the fact that the car runs lean untill secondaries hit at wide open throttle, I have had to keep the timing pretty advanced.

 

If I get a bigger jet on the primary of my 32/36, I should be able to bring the timing back to 9-10 degrees.

 

I am running straight off manifold vacuum right now, and so far its been reliable and runs great(other than its lean). I would recommend anyone with tuning issues on their 32/36 take the carb off, open the throttle and gently retorque the carb back down, then take a vacuum gauge and see if your ported vacuum is working right.

[mklotz70]

I'm not a carb expert by any means...in fact I'm having issues with mine backfiring when accelerating.....but....

 

 

The vac advance is to help with emissions when you accelerate from idle or closed throttle...you're dumping more fuel in, it takes longer to burn, so the advance starts the process sooner. The longer burn gives more power which is what you need/want when accelerating. The vac adv tube needs to be connected to the base of the weber...or any carb for that matter. Running on manifold vac basically pulls the diaphram all the time, therefore eliminating the vac adv. Race cars run a lot of initial advance and higher idle rpms to eliminate the need for a vac advance because it's idling right on the edge of the mechanical adv kicking in. Not practical for daily driving.

 

The weber is a bit touchy. You want the throttle plate closed as much as possible. The vac adv tube is connected to a small hole above the throttle plate. The more transition time there is before the throttle plate goes above the hole, the better. You can double check this by having your vac gauge hooked to the adv tube on the carb. You should have 0 vac at idle.

 

In my research to fix my prob, I came across a site....which I can't seem to find again....that said to get rid of the dead spot off idle, richen up the air mix. Basically, turn the air mix screw out 1/8 turn, hit the throttle...better?...It will probaby start running rough by the time you get 1/2 turn...depending on how lean you had the idle set already. It seemed to help on mine....my prob is similar to yours, just way more exagerated...so it might do the trick for you.

 

You can get a accel pump jet that will squirt on the secondary side....

 

http://www.pegasusautoracing.com/group.asp?GroupID=WEBERDGVP

 

The secondaries don't need the squirt from the accel pump because they are progressive. If it opened at the same time as the primary throttle plate, it would need it. As the secondary throttle plate opens, it will pull fuel through the venturi. I wouldn't mess with it...your prob is in the primary. I'm pretty sure the only reason it seems to be in the secondary is because you are stabbing the throttle so quickly.

 

Also....keep in mind that if you stab the throttle, it goes from max intake vacuum to 0 really quickly. The transition time for the throttle plate to uncover the hole that makes the vac adv signal is really short. It will always work better by with a slower pedal movement(like Hainz said). You can hook the vac gauge to the base of the carb and watch this. If you gradually run the rpms up, you'll see vac signal for a good while. If you stab the throttle, you'll see a momentary bump on the vac gauge, then nothing....so you've elimintated the vac signal before the dizzy even had time to react.

 

 

If you have the timing advanced too much, you'll be over advanced when the mechanical adv kicks in and the burn will start too early and you'll lose power.

 

The lower the rpms, the less advance you need. The higher the rpms, the more advance you need....that's why you'll have about 32-38 deg of adv if you check it while it's running around 3000rpm. The reason......fuel always burns at the same rate.....it doesn't burn faster when the rpm goes up......so you have to start the ignition cylcle sooner so that the full power of the explosion happens just as the piston starts going back down.

 

Okay...that's about it...need to get busy on my own friggin' carb prob!! :)