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Gomer, if you didn't get them from Blackline racing or someone like me, you should take them apart. New carbs NEED to be taken apart and CLEANED to hospital specs. There is often a lot of machining junk left in them. All orifices, reservoirs, and passages need to be blasted with carb cleaner and air dried. I usually use a blow gun with a rubber tip, set to about 20-25 pounds.

After cleaning, set the float height and drop(I use 11mm and 25mm), and give yourself a half-turn of the idle speed stops off of fully closed throttle plates. Also, open all 4 idle volume(mixture) screws 1.5 turns from closed.

Then once they're clean and set up, you can install them and run 'em.

Don't forget to set the fuel pressure at no more than 3 psi for Webers.


Last edited by DannyP
@DannyP posted:

Gomer, if you didn't get them from Blackline racing or someone like me, you should take them apart.


Bad news, if you haven't heard: Dave no longer works at Blackline and Justin moved up to Blackfoot Idaho.  It was nice to have such a great source locally. While it lasted. 

FWIW, my Spyder was up at Blackline having some adjustments made when I ran into that Puma convert and its owner. 

Yeah - Dave's whereabouts would be important to know......   The guy's a rock star!

He really is.

But to be clear, Dave was a product of the ACE (Art Thraen)/ Blackline Racing (Justin McCalliser) way of doing things. I'm sure that Blackline will continue to be an excellent resource for not just carb work, but VW engine machining, etc. We all panicked when Art left the business, but Justin took over without skipping a beat.

Nothing ever stays the same (much to my chagrin). 

I only asked because Dave became a friend over the years, and I was hoping he landed on his feet. It would be a waste to have somebody so talented working somewhere outside his field of expertise. 

Last edited by Stan Galat

Thanks guys, I got the set from CB performance. I have opened them up adjusted the floats and cleaned as needed. To be honest they were very clean and after all the reading and stories I was expecting to find crud inside. But no they looked like they had just gotten cleaned.  

I’ll be pulling the old off and making the swap this weekend.  

Out of curiosity on my VS will I still be able to pull the engine with the carbs installed like I could with the Singles? Or will I need to remove them. For engine R&R?  

also I read to set the floats at 14mil but in this thread you mentioned 11. That seams like a significant increase in bowl volume. 

SO try it that way and see how it runs through the transition from idles to mains. Three millimeters is about an 1/8", which really isn't a lot. More important is that the floats are set identically in both carburetors.

If your car goes lean in the transition, raise the float height. 10% ethanol requires more fuel to get the same result. I think that 14mm height might be before gas was poisoned with ethanol, but I could be wrong.

Last edited by DannyP

You probably won't notice much of a difference unless you're at full throttle and reading a wideband A/F gauge. Somewhere in the 1800-3000 rpm range, you might feel a little less oomph if it goes lean.

At part throttle you won't feel a difference.

Jet the idles and mains first, and make sure they're correct. Only then do you play with air correctors, emulsion tubes, and float height.

And make sure you're at 3 psi for IDFs, not over 3.5 MAX, that still holds true.


Last edited by DannyP

"Out of curiosity on my VS will I still be able to pull the engine with the carbs installed like I could with the Singles? Or will I need to remove them. For engine R&R?"@GomerP

With the air cleaners and pulley belt removed, you should be able to R&R the engine without taking the carbs off. . With car on jack stands and front wheels blocked, I always remove one of the rear wheels to slide the engine out the side through the wheel opening.

Good luck with your project! Looking forward to following your progress. 

@Stan Galat posted:

Nothing ever stays the same. Any idea where Dave landed?

Yeah - Dave's whereabouts would be important to know......   The guy's a rock star!

Yes, I know. And it’s not good news. I stopped by to get some new throttle plates and screws when I installed my new Venturis and I ruined one getting the old Venturi out. Justin was in the process of moving and he said one of the local school districts offered him a job in their bus maintenance facilities that was too good to pass up. 

I had my brother look up his info on Facebook on the off chance that I could coerce him into picking up some side work, but he never returned my phone call. I guess it’s left to the lucky ones that knew him well. 

Art rebuilt my Dellortos when I first bought them back in 2001-2002. Dave has serviced them ever since. I really miss having his experience to lean on. Oh well, I’ve got Danny now, thank goodness.

Got the carbs installed today. 
Had to relocate the fuel pressure regulator up on the engine wall. It was in the driver side wall and that space is now occupied by new shinny air cleaners. Now I am having a low pressure issue. max I can get out of my pump is about 1.5-2 psi. .. I did not have this issue before moving the regulator. Anyway it took a bit of fuss to sync the carbs and get the fast idle dialed in. Nothing unusual but space is a bit tight getting to the mixture screws. I had just enough time to take it out for a quick test run to see how she felt.
fFist impression with out touching the jets. Runs strong pulls hard and I don’t run out of power as soon at I hit 4200rpm. Like before.  The engine wants to keep spinning. I didn’t try to find redline. I do have a heavy lag when I stop the peddle so I’ll look into the fuel pressure first and then start on the jets tomorrow working with the wideband.   

in process photo don’t mind the bubble wrap and painters tape.  


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Like I said earlier, use that Wideband to set idle jet size and main jet size. All readings matter only at steady-state throttle. Adjust the transition from idle to main jets with air corrector jets, float level, and emulsion tubes(rarely need to change emulsion tubes).

Only then mess with the accelerator pump volume. I fatten mine up so it just starts to rich-bog, then turn them in until it falls on it's face(not enough pump). Open them a bit until lean/starve goes away. You're done.

Ok quick update and  seeking recommendations  

Wideband readings

idle 900RMs. 14:1

cruse 9.8- 10:1 (Main jet stacks removed) up to 2800 rpms then it fall off as expected  

 cruse 10:1 (Main jet stack installed) up to 2800)

cruse 13:8: above 2800-4000 

WOT 13.8:1 

 Current jets

  • Air Correction Jet: 2.00
  • Emulsion Tube: F-11
  • Main Jet: 1.15
  • Pump Jet: .50
  • Idle Jet: .55 (drilled)
  • Venturi: 28mm

Floats set at 14mm 

fuel pressure 3psi

Pulls hard up to above 5.5k

1915cc Vintage speedster. 

WOT I like 12.0 to just under 13.0, you might want to go up on mains a bit.

The 14:1 idle is perfect, but low speed cruise is WAY too rich. Don't know 100% what to change to fix that. I'll do a little research. I'm thinking you may want to go leaner/smaller on idle jets a little, to a 52.5 or even a 50.

I think John Connolly at jets them lean as heck, then opens the idle volume(that's what they are, they don't adjust the mixture, idle jets do that) screws a half-turn.

Last edited by DannyP

Well quick update

still chasing the idle jet AF  

still running rich on the idle jets 9.9-10.5 

Current  jets

45 idle 

125 Main

200 air 

At Idle I can get a good mixture using the adjusters  

still running about 10-10.5 in the idle circuit (cruse) under 2700rpm

WOT is 13.1

cruse above 4000 14.1  a little 2 on the nose and runs a tad HOT. 

i have a bit, and I do mean just a bit of a stumble at the end of the progression before the main kicked in  This went away when I went up to 130 mains. I’ll probably end up with the 130s    

I do have a SVDA  Pertronix 

I have ordered  some 40 idles  to see if I can get it to lean out but I am starting to wonder what’s up  I figured I would have gotten lean going from the 55 all the way down to the 45. But honestly not seeing much change on the merger or smell at cruse  

 Open to any opinions or comments. 

First off, I'm only familiar with Dellorto carbs, but I have read a lot about Webers and they are pretty similar in operation/jetting, so here's what I'm running on my 40mm Dells, set up by Dave Hogland when he was still at Blackline Racing:

The jet sizes are:

.45 idles

1.30 mains

160 air correctors (to slow down the fuel through the main jets to overcome the hesitation)  I might start with a 180 before hopping to the 160.

.35 Accelerator pump jets

32mm Venturis  

So my idles match yours, my Mains are slightly richer but the big difference might be the air correctors (200 AC is pretty big, in my book) and the Venturii size where mine is a 32.  I used to run a 34 main venturii and it had a bit of transition hesitation that is now gone.

That's all I've got.  Mine run great at around 14.1 most of the time, leaning out a bit on transition and then recovering but you can't feel anything (and that's what counts).

Ok so just a quick update

i Tried going down to 40 idle jets and honestly it ran pretty good until I hit the high side of the progression then I hit a big ass lean hole before the main jets kick in.  I tried a bigger main jet 130 to see if that would cover the hole. Don’t have larger air jets in hand to see if I can get the tip in to come in earlier so I tried once with the air correction jets removed this as I have read is about a 300 (compared to the 200) still had the big ass lean hole.  So 40 idles is to small, as expected. It might like 42s? Don’t have any in hand so I might try and ream out the 40s considering I have 2 sets of 40s.

I got a lot of questions on the float at 14mm so I adjusted it to 10mm as recommended, didn’t make a seat if the pants change but did riches up the AF mixture to the mid 11s. From the low 12s

I have ordered a variety of air jets

put the 45s and 125mains back in let left the float at 10mm and getting some seat time. Car runs strong but rich. need the car operating in the 17 as it’s scheduled to be the get away car at my daughter’s wedding so I might leave it alone for now. Better a little rich than in parts in the workbench.

open to ideas


Gomer, you're doing great, except for one thing.

If the idles are perfect, and the mains are perfect, leave them alone. Is it crisp sounding? Leave them alone, if it's too lean at idle  or slow speed then yes increase them. Likewise if the mixture is perfect at WOT above 3000 then mains are good.

A larger air jet is the opposite of what you want. To make the transition richer, you need smaller air correctors. The smaller jet(means faster air) and pulls more fuel and makes the transition earlier/richer. Go one or two sizes smaller on airs. If that doesn't work for you, you'll need emulsion tubes that richen the transition. For example, F7 usually comes with 40s and F11 usually comes with 44s.

Keep at it, you're close now.


thanks for the link I have been following John at info on tuning with a wideband he is a wealth of knowledge but this one is not making sense to me. About 1/2 way into this he talked about going bigger with Air correction jet to bring the main in earlier.
in his summary section at the bottom he states “#6. The hole between the progression circuit and the main circuit must disappear by gradually increasing the size of the air nozzle.”
Either way I have a few air correction jets in order so I’ll give this another shot once they arrive.

I did read that emulsion tubes come in "families" and you want to stick to the same family if you can, and you're not totally way off with what you've got.

Since you have F11, I think the one in the same family that richens the top end of the transition is the F15. If you can't fix it with air jet changes, then I'd try that F15.

Emulsion tubes aren't cheap compared to all the other jets.

The air correction jet is the most mis-explained part in these carbs. The Tomlinson "Dellorto Book" is particularly useless-- it says (basically), "just run 180s, and be happy".

@GomerP, I know there are a lot of voices on the internet, and it's hard to sort the wheat from the chaff-- but I've driven @DannyP's car. The man knows what he's doing. The throttle response and complete lack of a flat spot he's got (at least 50% of which is a result of crank-fire ignition) is astounding. He's going to EFI-- but after driving his car, I don't see the need for it. It was a revelation.

@DannyP posted:

Good explanation of air correction here:

^ That is a great little post, which explains the air-correction jet really well. Something similar on setting float height would square the circle.

I'm convinced that there are only about 10 people alive in the world right now who should be messing with emulsion tubes. 99.999% of us will never, ever get them close enough to warrant changing them.

Stan & Danny

thanks for all the help I agree the Tomlinson book is a waste as far as tuning. I would not recommend this book to anyone I have found multiple conflicting info within it. Do either of you have an opinion on the factory Weber tuning book?

I also couldn’t agree more the amount of conflicting info on the web.

I am normally an FI guy as I loved the factory Injection on my type4 I brought back from the dead.  
The beauty of the IDFs being so tunable is also the challenge. I am determined to get them as perfect as possible and I am enjoying the learning process.
I know I’ll be modifying the engine more over time so the learning is with the time.

I keep y’all posted when the air correction jets show up.


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@DannyP posted:

The only thing I'm going to say is that Stan's comments put a few nails in the coffin of the "Dellortos are better than Webers" thing.

I think the way your car runs says more about the guy tuning it than the built in superiority of one carb-type or another. I also think (and said) that at least 50% of the awesomeness is your ignition tune-- you've clearly taken this way, way further than almost anybody else.

The whole DRLA vs. IDF thing really seems to matter only to a very few people. Dellortos haven't been built for many, many years, and so the point is moot for most of us. Regardless-- the carbs are nearly identical for most practical purposes. They are just two ways to get to the same point, and the whole world is set up for IDFs. Every Dellorto out there is at least 35 years old.

For the vast majority of owners really struggling with plugged idle jets, the ability to access the jets from the top of the carbs (rather than from the outboard sides) in a very compact engine compartment is pretty darned nice. It's probably no more than that. The idle jet access isn't an issue for Spyder guys--  but it is for pan-based Speedster guys. "Better" means different things to different people.

It's clear that you can make your IDFs perform >= any Dellorto equipped car I've ever driven, but I suspect you could do the same for Dellortos as you can with IDFs. As I said, "I think this says more about the guy tuning the car than the built in superiority of one thing or another."

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