Topic: H8PVMNT Wrestles a Weber

[Gnarly4X]

Have you considered a colourtune, it goes in place of a spark plug and is made of pyrex allowing you a window into the chamber and thus the colour of the burn?
 

That product has been around awhile. I doubt that it is used by any serious "tuner", as most people probably have never heard of it.  Does anyone know someone who has used it or using it now to "tune" for AFR?

I'd rather spend the money on a cheap AF gauge.

Gnarls.

[LittleSteve]

That product has been around awhile. I doubt that it is used by any serious "tuner", as most people probably have never heard of it.  Does anyone know someone who has used it or using it now to "tune" for AFR?

I'd rather spend the money on a cheap AF gauge.

Gnarls.

I wasnt suggesting use it instead of an af gauge but as well as an af gauge. Im also aware that its been around for donkeys years, the old stuff usually works.
All the techs over here crap 'emselves when they see a carb these days seeing as how they died off in the nineties..

[H8PVMNT [OP]]

I would like to try one for the idle jets just to see what it looks like.  The only thing I could see is it would be kind of tough to read while driving with the secondaries under load .  I could put one of the boys on the cowl with the hood off...  Hmmm.

[H8PVMNT [OP]]

If I can get this thing dialed and then maybe learn how to do side drafts I will be the Bob Ross of Toyota carbs...

[Gnarly4X]

If I can get this thing dialed and then maybe learn how to do side drafts I will be the Bob Ross of Toyota carbs...

    Yeah... but YOU paint by numbers!! 

[emsvitil]

Have you considered a colourtune, it goes in place of a spark plug and is made of pyrex allowing you a window into the chamber and thus the colour of the burn?
 

And how are you going to look at a colourtune when driving ?

 

[LittleSteve]

You know you have them days when you wish you ad kept your gob shut

[Cheesemaker]

Interested in your results. 

I had one on my 85 Nissan Naps Z 4x4.   It ran good, and gave me a best of something like 28 mpg on a run one day.  I had 30's, and drove it hard.  And it ran good off road.  And my favorite was climbing steep hwy passes, down shift and put your foot to it, and the secondary would rip. 

The only issue I had was in the spring and fall, I had to adjust the choke, and idle.  But overall, it was 1000% better than the Hitachi POS that was on there. 

[H8PVMNT [OP]]

So far after getting the primary side dialed in a bit it has been fun watching the gas gauge NOT go down. This is exactly why I wanted to try this setup so I am pleased. No idea what I am getting on this tank but it's certainly better than I was getting.  I think the real advantage this carb has over stock is just how much you can tune it.

I don't know where my secondary is at as far as rich/lean but I can pull on hills I could only maintain on before when I use it.

[Cheesemaker]

I don't know where my secondary is at as far as rich/lean but I can pull on hills I could only maintain on before when I use it.

That was my experience with mine!  That'w were a Weber shines the most.

[Gnarly4X]

You know you have them days when you wish you ad kept your gob shut

Hey LittleSteve,

As you know the subjects discussed on almost all forums can be wide and deep and long or short, but it is ALL good.

Sharing thoughts, opinions, experience, and knowledge is what makes the internet forum venue fun and a great place to learn.

Wishing I had kept my mouth shut…. that happens to me just about every day. 

Gnarls.

[Gnarly4X]

Interested in your results. 

I had one on my 85 Nissan Naps Z 4x4.   It ran good, and gave me a best of something like 28 mpg on a run one day.  I had 30's, and drove it hard.  And it ran good off road.  And my favorite was climbing steep hwy passes, down shift and put your foot to it, and the secondary would rip. 

The only issue I had was in the spring and fall, I had to adjust the choke, and idle.  But overall, it was 1000% better than the Hitachi POS that was on there. 

Keep in mind that the Aisin carb designed for the 20/22s was to perform in a very broad range of environments while complying with all the "regulations and laws" at the time.  Although climbing hills was part of the design, so was avoiding the need for the owner to "to adjust the choke, and idle" in spring and fall.  Fuel mileage for the consumer was also a key issue and consideration.

With performance modifications, there's usually a trade-off.

Gnarls.

[Gillesdetrail]

I hope you don't mind me documenting my weber tuning stories as well so we can keep the information in one thread!
I have received and installed my 140 main jets (with 170 air correctors), it runs perfect in all conditions except for full throttle below 3500 rpms. It is pig rich. So rich that my a/f gauge doesn't even register, it goes to 9.0:1. Is it only the main circuit that controls WOT at low rpm? After 3800 rpms it is nice and steady at 12.5:1 and pulls hard up to 4900-5000 rpms, I guess it is at that rpm that the air correctors aerate the main circuit to lean it out.  I think I will take my f50 emulsion tubes and solder some holes on top and drill some holes in the bottom to lean out low rpm WOT, I don't know if it will work but I'll try! If it doesn't work i'll try 130 mains and 150 air correctors.

[H8PVMNT [OP]]

I hope you don't mind me documenting my weber tuning stories as well so we can keep the information in one thread!
I have received and installed my 140 main jets (with 170 air correctors), it runs perfect in all conditions except for full throttle below 3500 rpms. It is pig rich. So rich that my a/f gauge doesn't even register, it goes to 9.0:1. Is it only the main circuit that controls WOT at low rpm? After 3800 rpms it is nice and steady at 12.5:1 and pulls hard up to 4900-5000 rpms, I guess it is at that rpm that the air correctors aerate the main circuit to lean it out.  I think I will take my f50 emulsion tubes and solder some holes on top and drill some holes in the bottom to lean out low rpm WOT, I don't know if it will work but I'll try! If it doesn't work i'll try 130 mains and 150 air correctors.

Fine with me.  The more information the better.  What is your engine setup and your typical day to day elevation, etc?

[Mudder]

H8, have you tried to run the distributor off of manifold vacuum and not ported vacuum of the carb?

[Gnarly4X]

H8, have you tried to run the distributor off of manifold vacuum and not ported vacuum of the carb?

Wouldn't the carb vacuum fluctuate?  The manifold vacuum should remain relatively constant.

Gnarls.

[H8PVMNT [OP]]

Yeah I did that once on the Aisan, but it felt wrong.  I got too much too soon.  I haven't tried it on this carb yet.  I am running both vac lines to the vac advance.  The manifold vac is on the second diaphragm port and the ported one is on the front main port on the distributor.  It is getting full advance.

I am pretty much happy with the way the Weber is running, but I will mess with the secondary side soon. I have a couple more jets coming for some very conservative adjustments.

[Gillesdetrail]

Fine with me.  The more information the better.  What is your engine setup and your typical day to day elevation, etc?

weber 38/38 syncro with choke plates removed
transdapt weber to 20r adapter (2" spacer)
20r light ported intake ("bridge" removed and entry smoothed out and radiused, runners 40 grit finish)
20r head ported, oversized 20r valves (still smaller than 22r valves) 0.015" shaved
DT 4-2-1 header 2" exhaust
Adjustable cam gear set at 0.
Suzuki sidekick primary spring in the distributor, 11* base timing 91 oct
About 160 feet most of the time, 1300ft altitude when in the trails

idle 45/45 about 1.25 turns out
main 140/140
f6 emulsion tubes
170 air correctors
3 psi
18&28mm float level

The issue that I have always had was stupid rich at full throttle below 3000 rpms. It would spew black smoke and I had more power at 75% throttle than 100%. I changed the emulsion tubes from f50 to f6 with 150 mains and 190 air. It pulled better after 4K but same low rpm problem. I ran it like that for a while and now just got a wideband. I tried 145 and 140 mains, still way too rich (below 9.0:1 afr under 3500 rpms). Last week-end I soldered and drilled two main jets to roughly 135 and still too rich at low rpm but a bit better, but now too lean up top, I need smaller air correctors to compensate. I tried raising the float height to 16&26mm, no change. Then back to 18&28 and I lowered fuel pressure to 2psi, same thing. I lost one of my f50 emulsion tubes so I drilled my f6, I flipped them upside down and drilled two extra holes at the bottom and enlarged two existing holes. I watched a David Vizard youtube seminar video on the DCOE carbs where he said to flip the tubes upside down and to look at the position of the holes. More bottom holes to lean out low rpm, middle for midrange and top for top range. I didn't know if it applied for our downdraft carbs but I wanted to experiment.

It is now below 10.5:1 from 3000 to redline and seems to pull harder from 2500 to redline, but still under 9.0:1 below 2.5k. Very puzzled by this. That means I still have a bit more power left if I adjust the mixture to around 13.1:1, which is awesome because it is pretty quick now as is, but I can't understand the richness issue, most stock 22r run a main jet of around 145 and mine feels way faster than stock. Maybe I am just under cammed? Should I order 120-125-130 mains and 150 air correctors? Try more emulsion jet tuning? If I run more timing it pings when carrying heavy loads.

[Gnarly4X]

Gillesdetrail... what is your elevation?

Gnarls.

[H8PVMNT [OP]]

He said he was at 160ft, and up to 1,300ft, so pretty low elevation.  I am just learning this carb, but so far the one thing I have learned is to make just one change at a time.  It's really tempting to change air correctors while changing jets because you all ready have the top off, but when I did that I made too much change and didn't know which change made me too lean.

If I were you I would start by changing just the main jets, one step at a time and see what happens.  Supposedly the air correctors are only in plat at higher RPMs, but I don't know for sure without an AF gauge.  After you mess with the mains and note changes and get them where you want, then change the air correctors and see if leaner ones help your WOT problem or not.  If they make a difference then they are in play at lower RPMs after all.

I was reading on a Datsun forum about guys messing with the emulsion tubes on these, so I think you are on to something there.  I'm not ready to dive into those until I get my secondary dialed in and get an AF gauge .  If you do it please post the results and what it did to your AF so we can learn more.

You should start a Weber 38 thread since it's a bit different and you have to change both sides at once.

[H8PVMNT [OP]]

I got the jets to adjust my secondary side just one step today. I only had the jets for two steps before and that was too much. So if I have time I will start that...

Afternoon update:  One step leaner on the secondary made no ill effects...

[H8PVMNT [OP]]

Tested out the hill climb mod today.  This hill doesn't look like much on the video but it has been enough to make a stock carb load up when you go this slow, so it should be enough to flood a Weber...  But this one worked like EFI .

https://youtu.be/NWmlKSzVDT0

[Gillesdetrail]

He said he was at 160ft, and up to 1,300ft, so pretty low elevation.  I am just learning this carb, but so far the one thing I have learned is to make just one change at a time.  It's really tempting to change air correctors while changing jets because you all ready have the top off, but when I did that I made too much change and didn't know which change made me too lean.

If I were you I would start by changing just the main jets, one step at a time and see what happens.  Supposedly the air correctors are only in plat at higher RPMs, but I don't know for sure without an AF gauge.  After you mess with the mains and note changes and get them where you want, then change the air correctors and see if leaner ones help your WOT problem or not.  If they make a difference then they are in play at lower RPMs after all.

I was reading on a Datsun forum about guys messing with the emulsion tubes on these, so I think you are on to something there.  I'm not ready to dive into those until I get my secondary dialed in and get an AF gauge .  If you do it please post the results and what it did to your AF so we can learn more.

You should start a Weber 38 thread since it's a bit different and you have to change both sides at once.

Yes the air corrector leans out the top end, on my set-up I can see the effect or the air correctors starting at 4200-4300. I made one change at a time on the jets without changing air correctors, then depending on the a/f I increased or reduced them to get linear a/f. To me my wideband is invaluable for accurate adjustements.

So far going from the f50 to f6 tubes made it run better all around part throttle and full throttle, but my f50 setup was not finely tuned. Adding 2 more holes and enlarging 2 more at the bottom of the f6 tube made the whole mixture richer from 12.5 to 10:1 from 3000-5000 but from 9.0 to 10.0 from 2500-3000. I need to buy more jets and ac!! I'll try 125 and 130 mains and 150 air correctors. I may want to try f7 tubes too.

[H8PVMNT [OP]]

I am almost through the secondary side.  Today I swapped I step leaner on my secondary main and while I didn't get pre-detonation I had a little less perceived power on my test hill.  It just felt a bit too lean to me, so I swapped back to a 135, which seems to be the happy place.  Actually I have a 135 on both main jets now.  I don't feel I can go any leaner without an AF gauge.

I swapped the secondary air corrector on step leaner at the end of lunch so we will see how that goes.

Mileage has varied from 14.5 to 15.5, power is good.  Basically I am getting the mileage of my stock carb in stock trim but have the performance of the highly messed with, stripped down stock carb that was getting 11-13 mpg.  My dream is to break 16 mpg on the day to day with the Weber.

It's odd but tuning the Weber is helping me understand some of the other circuits in the Aisan carb better.  The mail difference is I can make changes to the Weber that I couldn't make to the stocker.  I haven't ran this long enough to claim any preference but I am pretty happy with this thing so far...

[Gnarly4X]

....  My dream is to break 16 mpg on the day to day with the Weber.

This is really great stuff!! 

16 MPG..... when going to church on Sunday morning, pretend you are an old fart driving with your precious family..... and the price of gasoline is $10 a gallon. 

Gnarls. 

[H8PVMNT [OP]]

Haha, that's the problem with carb/engine mods and getting more response and better acceleration.  You tend to want to enjoy it and it's harder to stay off the throttle .

[Gnarly4X]

Haha, that's the problem with carb/engine mods and getting more response and better acceleration.  You tend to want to enjoy it and it's harder to stay off the throttle .

Almost all of the vehicles I've owned, I have always aerobically exercised them well.  Gas mileage at times was on my mind, but somehow disappeared as I pressed the gas pedal down hard against the floorboard and felt that exhilarating little adrenaline rush!!

Gnarls.

[300k]

and felt that exhilarating little adrenaline rush!!

A feeling only sweet 90 horsepower can bring

[kneedownnate]

Haha, that's the problem with carb/engine mods and getting more response and better acceleration.  You tend to want to enjoy it and it's harder to stay off the throttle .

Best I got with my weber was 19 mpg, kicking, bucking and gutless the whole way.  Soon as I got back from passing smog it changed to 14-15 mpg with good power and better driveability.  Still never did well at angles, even with the high angle mod. 

[Plainview]

H8PVMNT - Good to know I'm not the only one who's run into that tab hitting the adapter plate issue.  That's just one of several issues I've had with mine that make me think QC is pretty much nonexistent on these things.

One thing I've never been able to achieve is a smooth idle and some checking around the carb baseplate reveals I have vacuum leaks at both primary and secondary throttle shafts.  I ordered a set of sealed throttle shaft bearings from Pegasus Racing but have yet to get around to installing them.

The fact that a brand-new carb leaks like this, plus the problem I had with the primary throttle plate binding in the bore and that tab issue just makes me roll my eyes.  OTOH, I figure if I ever get it set up just right it'll probably be a thing of beauty.  And then I'll do a V6 swap... LOL.