What size jets 4 Webers?

First step is to verify that jetting for both sides is the same; as well look at the venturis to make sure they are the same. Read http://www.aircooled.net/synch...-vw-carburetors-103/ and http://www.aircooled.net/vw-carburetors-jetting-102/ 

Any recommendations that people can give you will get you close (every motor is different), but probably be a little rich so you'll need to do some experimentation to get it right on. Aircooled.net is a very good source (John is very knowledgable and used to have a trade back program so you didn't end up with a fortune invested in jets you weren't using), as is Gene Berg Enterprises (they are very VW specifically knowledgable as well) and Pierce Manifolds.

PS- Make sure the air filters are sealing to the bases and tops; the cast aluminum are supposed to be better than the stamped steel (although I never had a problem with the steel ones). K&N has a grease specifically for sealing the filter assemblies to the tops and bottoms. There are also taller jet holders that raise the air intake into the jets up off the level of the air cleaner bottoms.

Al, all good source info -- thanks.  I am particular about cleaning, and use the grease.  I have a pair of Jet Doctor extension tubes, and am contemplating installing them during the planned blitzkreig of R&R, jet sizing, etc.  I also use rain hats.

Everything stated above is applicable.....   As you know, any thing above 2750 / 3000 rpm is being fed by the main jets, which does point to idle jet problems....   A good start size would be .60 , .65 , or possibly .70.....    First step, as stated, is to check what you have.....   The markings on the jets may be wrong as the jets may have been drilled.....  A jet guage or the availability of MM size drill bits will help you here....   Just my .02...

Frazer- Have you verified that the float levels are correct? No amount of monkeying around with these things will work if the floats aren't set first.

Kelly...  Were these carbs purchased "new" or "used" ?    Or did they come on the car??

I was fighting a pair of Dels on my engine just before Carlisle....  Multiple problems....  Worn out cross bar pivots....  K&N filters so old they were litteraly falling apart...  Miss matched arms on the throttle shafts... a worn actuator rod on one accel pump... and the connector (threaded) links were worn out and binding...

I don't know how old the build was when I got it, but it was a half assed job...

After major rebuild of carbs, linkage, and pump replacement, things started flying right...

While you have the carbs off, compare everything.....

Just to second what's already been typed, Start with checking/setting your float levels - that's probably the most critical thing you can do, as everything builds off of that - and then check your jet sizes with a jet tool (an ID probe in either mm's or thousandths - if you can't find one, get a torch tip reamer from a welding supply store - you may have to convert .000's to metric).  Once you've checked your jet sizes, report back and we'll try to move you in the right direction (probably down, from what you've already said).  It will be nice to know the size of the air correction, too, although if it's near 180 you're probably OK.  DO NOT believe the number stamped on the jet(s).  For instance, Pearl has idle jets that say .060 but they're really .0612, as they've been reamed a tad (by me).  That gets me to 14.5 on my a/f meter.

Lastly, NEVER assume that anything coming from JPS is (a.) the same as what you've already got or (b.) even what he says it is.  Also, you can not assume that ANY carb coming right out of the box is even remotely set up to run properly - they aren't.  Not Webers, not Dells, not any of 'em.  Either the float levels are way off, or the jets aren't right for your engine or the accel pumps are mis-adjusted or something, but it's always something.

So, young fella......trudge off to the garage and dive into those liquid atomizers and tell us what'cha got to start with and probably someone will be able to help you get them dialed in (or, at least, we'll have fun arguing about it).

I've bought all of my jets from CB Performance, but I know that Berg carries a wide line, too.  Once you know what you've got, all you'll probably need is one or two sizes more in whatever direction makes sense.  I've never installed the Weber Jet Doctors.  I have the CB horizontal discharge tubes on my Dells and like them, but I've never had anything else so what do I know??

Gordon

Yo, Gordo -- let me explain it to you: you know EVERYTHING!!

So here is input from Henry, his recommendation for this size/type engine:

Kelly.......    I originaly had .55 idle jets supplied with the CB Perf. 1915 engine in my Spyder......  At part throttle the engine would "hunt" sounding like YAH, YAH, YAH, etc.......   The jets were tooooo small....  Problem cured with .60 jets....  Your engine is almost a half liter larger.....So just keep things in mind....

Pat Downs said he supplied all his engines with a "book" correct jet set, but as stated, "No two engines are alike."

Yeah, that's true.  My 2,110 has 61.2 idles and 155 mains on Dell 40's.  On the idle jets I run about 14.5 on the A/F meter, and when it transitions to the mains it drops to 13.5-ish to be a tad rich (but not too bad).

Kelly:  I'll stop by Eastern bearing today or tomorrow to see what they have (or can get) for heim's.  I could call, but then I'd miss the tattoo'd biker chick in the office.  Don't get me wrong, though - that lady knows more about bearings and their applications than anyone I've ever met.  Everything else for the kit I'm pretty sure I have kicking around and I've put it aside so I know where it is as I've been re-arranging the shop with all my ex-Beaufort stuff.  I'll see about making up a "Kelly Kare PacKage" next week.

gn

61.2mm ? really .2mm?  how the heck did you drill those (or where did you get them)?

I used oxy-acetlene torch tip reamers but all you have to do is find a drill the right diameter (I have a set of machinist's drills that are indexed pretty fine, too).  These aren't tapered jets, nor do they have a conical entry so a regular drill works just fine.

Local suppliers of these drill bits are normally in the machine shop supply business.....A call to a local machine shop will usually get you a list of those suppliers over the phone....If that won't work, there is always McMaster-Carr....

Leon,

Good to hear your experience w/ the size for idle jets.  Once I know what's what, I may want to try 0.60s.  Gotta get in there first.  I ordered a small set of metric drills in the sizes ranges that I am supposed to be using.  Couple of bucks each.  Found a place on line that carries these listed in 0.05mm increments -!-.  These will be my bore gauges.

Now you're thinkin!

If you REALLY want the easiest and fastest way to dial in your carbs,go to ebay and type in "AEM wideband gauge". Buy this,and weld the included bung into your header collector and you can install this gauge permanently,or you can make a rig like I did where I plug it into a 12V cig lighter receptacle and only use it when I am tuning. This gauge will give you accurate,easy to read real-time air-fuel ratio readings and you can easily figure out where you have rich or lean holes in your cars tuning.

 Do not be tempted to try to emulate modern car-EFi type air-fuel ratios however. I have learned that the air cooled VW does not have a very efficient head design and thermal efficiency,so they like to run a point or so  richer than modern cars.

 I have mine dialed in and it runs so good,I want to cry sometimes....just out of pure joy. Get the wideband gauge,and start tuning. Your engine is big,I would say 60-65 idles,and 155-160 mains atleast. good luck!  

For anyone interested, Pierce Manifolds has what looks like a nice jet drill set

http://www.piercemanifolds.com...uct_p/98.0181.00.htm

Mr Bond, James Bond . . .

Getting A/F ratio data would be very nice, I appreciate the recommendation.  Have seen the adapters, and so could go that route.  maybe that would be step 3.  Need to find a welder guy who could do the work.The parts via UPS are starting to accumulate, so I may be getting into this is a couple of weeks yet.

The AEM gage comes with the "bung",you simply drill a hole in the merge collector and Mig weld this threded bung in,hook up + & - 12V to the gauge and you are ready to tune. It really takes ALL the guesswork and learning curve out of tuning. It really helps when diagnosing stumbles/flat spots in the powerband and tells you if you eed to go richer or leaner instead of just reading plugs and chasing your tail. Get that gauge setup and 4 of those EMPI snails and you will be happy you can actually tune it yourself with some time & patience. Good luck! 

Kelly:

I installed a CB in-car A/F ratio gauge a number of years ago.  Came with a bung as stated above, so I took it and the exhaust collector to a local guy who builds custom, "chopper" motorcycles and he welded it in.  He wouldn't charge me for it, only asking that I return with the car to show him, later.

Most welders will quote big bucks to install it in the car, but very little if you remove the exhaust collector, pre-drill the hole where you want it and then just take them the parts and drop them off.

If you get one, get one with heated oxygen sensor.  They warm up, stabilize and start to work in about 45 seconds.

If you go the A/F gauge route (I HIGHLY recommend it) read the tuning article by John at Aircooled. I got the Innovate in car unit and with it and his info you can determine which area to work on. IE: idles for one range, airs for the mains tip in, and mains for the top end.

Last laugh is on me......   I ordered some 52s idle jets for the Dels in my car as the ones in the carbs were way too big....   Jets arrived, but I was not able to jump right into the job... 

I wanted to start with the .52 dia. and incresae (drill) in stages to some where around .55 / .56....  When I installed the new jets "as is", the engine was a nightmare....   Spit, sputter,

ragged transition,surging, etc....  So I pulled out the drill set and guess what....The new, clearly marked 52s were actualy 46s....  This is from one of the more reliable suppliers, so take heed.....  It seems you get little assurance from past experience....  Check everything TWICE.... 

Gordon, any chance you could post some pics? I have bungs already installed in my tail pipes, but I don't know if the setup that you have described would work in my car. Sure would like to see what you came up with.

Barry

So how big did you have to go?

Just a note: you don't want the oxygen sensor too close to the open air (most people will put the bung in the head pipe after the collector and before the muffler) as at idle and just above there can be fresh air mixing the exhaust, diluting the mix and giving false readings. I take it from reading your post you don't have a 4 into 1 header and muffler arrangement?

Right now they are .55...  I'll run a tank of gas through them, check the gas milage and see if I can get  air fuel reading from a local garage....Looking for arounnd 13.5....

If I recall correctly some jets (IE: Webers) are in metric. Also they're flow rated and as I've read modifying them affects the flow rate. That said if you have an A/F gauge you'll get to where your engine needs to be.

Did work up to .55 in a couple of stages (what sizes did you try first?) or drill them out that size straight away?

I went 46, 52, 53.5, 55.....    55s had the engine responding in a reasonable manner....   May have to go as far as 60 for the desired air /fuel numbers....

I had 50's in mine....always had recurring problems. I took it to a aircooled specialist who said no VW should ever have less than 55's. He tried 55's in mine and he thought it still wasn't quite right. Changed them to 60's and the car runs like a dream. With the 50's it was always difficult driving through Richmond park (speed limit of 20mph) 2-3 gear up and down. Now 3rd gear and pulls smoothly.

For those who would like a very comprehensive guide for Weber carburetors you should check out Mark Harney's site, Carburetor Clinic: http://www.carburetorclinic.com/index.html