Tampa VW


 
HomePortalFAQRegisterLog in
Just updated the members map please add yourself to it .. No need to put your home address just your city and Zip code. Please use the Key color.
Locate it in the Introduce Yourself area



If your not Logged In your not able to see EVERYTHING so LOGIN what r u waiting for Smile
Top posters
K1
 
Hellafast
 
MadMike
 
U B BUGN
 
the-jerm
 
baja69
 
Stuka
 
muddobber
 
panther
 
Chris P.
 
Latest topics
» >> Post your mind <<
5/26/2014, 4:01 pm by kidr32

» Rusty floor pans
4/29/2014, 9:46 pm by DonnaSC

» Subaru swap
9/8/2013, 11:25 pm by Nullifier

» Bye to a friend
6/2/2013, 1:00 pm by Stuka

» Mays Hot VW's
4/24/2013, 8:04 pm by allisontech

» Now that it's running great, I've got to change something!
3/4/2013, 5:24 am by allisontech

» Roxy's Restoration
2/16/2013, 7:26 am by allisontech

» Valve adjustment and Timming video's (Vintage VW Training Film)
1/20/2013, 6:55 pm by rosie007

» How did club members do at this years Pasco Bug jam?
1/2/2013, 5:24 pm by allisontech

» Wishing everyone a Marry Christmas
12/26/2012, 6:35 pm by allisontech

September 2014
MonTueWedThuFriSatSun
1234567
891011121314
15161718192021
22232425262728
2930     
CalendarCalendar
Like this topic? Show it by clicking the Like Button.
Facebook
Tampa Vw Net

Create Your Badge
SocialTwist Tell-a-Friend
Loading
Tuning Dual Weber IDF Carbs on the VW Type 1 Engine511
Share | 
 

 Tuning Dual Weber IDF Carbs on the VW Type 1 Engine

View previous topic View next topic Go down 
AuthorMessage
K1
Admin
Admin


Location: in the back shed

PostSubject: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   11/25/2011, 11:01 pm

First of all I give full props to [You must be registered and logged in to see this link.] for this write up: Great info occasion


[You must be registered and logged in to see this image.]
[You must be registered and logged in to see this image.]
[You must be registered and logged in to see this image.]

Tuning Dual Weber IDF Carbs on the VW Type 1 Engine

A fact - Weber carburetors never come out of the box clean or jetted perfectly for your engine. If you order a set, they may come to you in the ballpark, but every engine is different, even two engines built with the same parts. You're going to be needing some different jet sizes. No way around it, if you want to get it right. Buying jets is just part of it and you have to be ok with that if you want to go to the trouble to tune things well. Jets are expensive, so if you know someone that has a stockpile of them to lend you, get them and start tuning away. If not, you'll end up with a few sets that you can probably sell off for close to what you have in them.

"Ok, well, I'm smart.. and I am handy with the drill bits.." Well, good for you, sport. For the most part, stick to correctly sized and calibrated idle jets. The holes are SMALL, and small defects in your drillings will add up to big discrepancies in fuel delivery. If you want to get handy with the main or air correction jets, go for it, they're much bigger and will not suffer so badly because you sneezed.

First things first. If you do not have an understanding of the otto cycle, go read about it so you know that what the engine does with intake and exhaust are not separate events from each other. The exhaust cycle contributes to the intake cycle. Given this fact and the carburetor's dependency on the health of the otto cycle, you must make sure that your engine is healthy before you spend any time tuning your carburetors.

Your engine's health - Are your valves correctly adjusted? Is your timing set correctly? Are you SURE? If not, find out. If you don't know what the right timing is, FIND OUT. Don't guess.
Are your carbs CLEAN? Are your floats set correctly? Clean the carbs and adjust the floats. Here is a cleaning procedure that should clean out most carbs, especially new or fairly new ones. Older ones may need more attention. If you slack on this step, the rest will be meaningless and frustrating.
After you adjust the floats, you need to make sure your fuel pressure is about 3 to 3.5 psi. If it's too high or too low you will have poor results. Don't ASSUME anything about the fuel pressure. A stock pump under the wrong conditions can supply 10 psi of fuel pressure. I use an internally regulated rotary pump that runs about 3.5 psi. If your mechanical pump is pumping too much pressure you can add gaskets under it to get it right, or you can put a regulator in place. You also have to make sure you have the right pump and fuel pump rod combination. That is beyond the scope of this article. If you suspect there is a problem, deal with it and come back to this. I like the rotary pumps because you have instant fuel pressure, and your float bowls will be filled properly when you turn the key on.

Venturi selection - For engines that rev pretty high (6000-7000 rpm), you are best off choosing vents that are about 2 to 4mm smaller than your intake valve size.

For engines that are set up for torque, like bus engines, and other torque-happy applications, you can go a little smaller on the vents and get better low end response. For these, I'd recommend 4 to 6mm smaller than your intake valve size.

So what happens if your vents are too big? You'll have reduced air-speed at low RPMs, which makes tuning harder. Air speed is one of the things that tells your different fuel circuits when to start to come on. It will be soggy down low.

So what happens if your vents are too small? The undersized vents will restrict your engine's ability to breathe at higher RPMs.

How critical is it? Not terribly, but if you're way off it will matter, and you will feel it. Putting 40 vents in a set of 44 IDFs with 40mm intake valves will be pretty soggy down low. Sticking with the 36's would be about right. Putting 28 vents into a set of 40 IDFs on an engine with 40mm intake valves will limit your top end noticeably as well. A set of 44 IDFs, for example, can me made to work on many engine sizes with the standard 36 vents, but you might find that you could optimize them better if you are willing to spend the money and try some different vents that would be ideal for your application.

A few notes about jets
More recently made jets are a little different in shape from the standard ones made by Weber, and there are some characteristics of them that could use a little attention. The key thing to watch out for when installing new jets is blockage and burrs. Don't assume that they're clean out of the package. Many have little bits of crap in them that will cause you misery if you just install them. Clean them out with carb spray and look in them to make sure you have them clean. =_blank&tp=inuvo&link_id=-10391983&cid=974&pid=1]Compressed air is very handy too for blowing them out after you spray them. Get them clean and dry before you install them. Many have burrs along the split areas where they compress to fit into your jet stack or idle jet holder. Inspect for this and get it cleaned off before you install them, or the burrs can chip off and fall into the stack or holder, causing blockage. Check it all. I like to clean them, install them in the holders or stacks, and then pull them out and clean it again, to be sure.. Then you know if anything was going to chip off it did, and has been cleaned out.

It's wise to invest in a set of jet gauges to inspect the jets you use, to make sure they have not been changed. If you trust the stamped or screened writing, you might end up with results you do not expect. I've had them come to me sized wrong a couple times. While I don't like to ream jets, I think having a reamer/sizer is handy for checking them, and sizing them in a pinch. I personally think it is a wise (albeit expensive) choice to have an arsenal of correctly sized jets of all increments around the range that you need to use, but that's something you will likely accrue if you build a few different sized engines with some different combinations of carbs.

Idle jetting
Once you've settled on your vents and your carbs are adjusted and cleaned up, you can choose your idle jet size. I've noted a formula in the books (basically 1.6 * vent size) for idle jet sizes, and I have to say that vent size has little to do with idle jets, on the vw engine at least. More efficient engines can benefit from leaner idle jets, and less efficient engines probably need a little more. 50-60 is the range, and there is a trend toward larger jets for larger carb bodies. The throttle plate size is a key factor.

Idle jets are usually 45-65 in size, mostly in the 55 range. The rule is typically to multiply the vent size x 1.6 to arrive at your rough idle jet size, but what I've seen is that 50 to 55 is mainstream for about any 40 or 44 IDF. 55's will make sure you're not leaning out when you are tuning, so I start with those.

Before you do any more, MAKE SURE the air bypass screws are CLOSED. These are the little screws and lock nuts that are next to the mixture screws. If they are not closed, you'll probably never get it jetted right.

Now. This article assumes that your engine is in top notch condition before you go about tuning the carbs. That means general engine health, timing, dwell, fuel delivery, fuel quality, all the way down the list. And all THAT's another subject.
After installing your idle jets, you close the idle mixture screws and unscrew them all about the same amount, maybe about 1.5 turns out. Then, with your linkage disconnected, unscrew the idle speed screws (the ones the throttle arms rest on) until they are no longer touching the arms, and then turn them back until they are JUST touching. Now turn them in another half turn or so. Start the engine, and after you get it warmed up a little, see if it will idle ok. Now get your synchrometer (Unisyns suck, get a snail if you don't have one) and use the idle speed screws to even it out, and get you to a reasonable idle speed. Not too fast, keep the idle speed down for now, and get it even. If not then turn each mixture screw out another turn. If it STILL will not idle well, then your idle jets could be too small. Now get your synchrometer and use the idle speed screws to even it out, and get you to a reasonable idle speed. Not too fast, keep the idle speed down for now, and get it even using the snail. The snail readings at a proper idle should be between 4 and 6 or so.
Now go to each mixture screw one at a time and slowly turn it in (by slowly, turn it about 1/8 to 1/4 turn at a time and stop and wait for the response of the engine for a few seconds) until the engine begins to slow down (you'll be leaning out a cylinder). Now slowly back the screw back out (same method you used to screw it in) until that cylinder starts to pick up again and run smooth. This is the critical point in the mixture adjustment. Slowly open the screw a little more at a time until you reach a maximum idle speed. Don't go any further! If you're not sure, stop there, screw in back in until the idle drops, and then start to back it out again until you feel confident you have unscrewed the minimum amount that you have to in order to get max idle speed from that screw. Move on to the next cylinder. Do this until you have done all 4 cylinders.

Now back to the synchrometer. Get them as close to the same as you can, and at the target idle speed you want. 800-900 is a reasonable range. Lower you can get and live with it, the better IMO.

You're getting close now. Repeat the idle mixture procedure and when that is done, if your idle is right, you're done with the idle settings for now. If your idle is now off, go back to the synchrometer and idle speed screws.

These iterations help you trim it out - you start low on idle, get your mixture right, and then move the idle up, and check mixture again, and if you have to adjust your mixture to the point that it messes up your idle, then you adjust that, and mixtures one more time and you should have it. If you don't have it by now, you are probably doing something wrong.

So what do you do if two barrels on one of your carbs are not flowing the same? If it's only about quarter point or less, don't sweat it - it's most likely to affect your idle more than anything, maybe a weaker or more eager barrel at idle. If it is more than that, your carbs need attention, namely that the throttle shaft may be bent, or there may be a problem with the butterfly plate or its alignment, or something else causing different air flow. Some people recommend using the air bypass screws to adjust it, and this does help, but if it's more than a point off, it will cause problems that the air bypass can't account for. They need to be FIXED if this is the case. I never use the air bypass screws for more than about a point of difference.

Main jetting
Now with the idle jetting done, main jets are next in line. Assuming F11 emulsion tubes, your starting point for main jets is about 4.1 to 4.3 x the vent size. So for a 36 vent, your main jet should be roughly 145 to 155 to start. 150's a good choice to start with unless you're feeling lucky, in which case you can start with a 145. With a 145-150 main jet, you'll be pretty close with a 36 vent. Similar rules work for smaller and larger vents, though once you get past 40mm vents, the rules don't seem to apply so well.

Air jetting
Air jets are more empirical, but a good starting point for them is about 200 if you have 145 mains. If your mains are considerably smaller, like 135 or 115 or something, a 160 to 180 air jet is a better place to start. Start there and don't mess with them until you know the other jets are right.

Synchronization
This is a topic that does not get enough attention. Synchronization is EVERYTHING after the jetting is done. Synchronization will such a difference in the way it runs you just can't believe it when they are right. Unfortunately all the linkage that is out there has certain characteristics that keep your synchronization from being perfect all the time, so all you can do is get it close and keep after it every once in a while.

The biggest problem with synchronization is keeping the geometry correct. This is hard to understand without illustrations of why, but if you just trust that it's important, you can avoid all the rest.

Linkage
There are different kinds of linkage out there, and a lot of people use crossbar linkage, while some others use bellcrank type linkage. Each one has its application, but I prefer bellcrank when I can use it and can get good linkage.

Crossbar linkage: How to ensure that your downrods have the right geometry

With your downrods, if you can position the crossbar arms so that your downrods are vertical (left to right), that will help matters, and complicate the situation less. Once you have achieved that, you can work on making sure that they are both at the same angle (leaning from front to back of the car). Use an angle finder, and read what the rods are, and use washers to get them the same. There shouldn't be a lot of difference to start with, if you have the right linkage for your setup. Different intake manifold types (offset versus straight) will use different linkage setups. If your crossbar is sitting at an angle with respect to your fanshroud, you have the wrong linkage.

Once your downrods are at the same angle side for side, then your synchronization will be easier, because the throttles should now be offsetting the same amount on each side throughout the full range.

Now, to synch your carbs, loosen the nuts on one downrod, and use the rod's opposed threads to set the carbs so they are opening at the same time. Be careful when doing this (I do it with the engine off) so that you don't open them a lot too many times.. you'll dump a bunch of fuel into the engine if you do. When you test, make sure that you are using the point where the cable connects to the throttle arm in the middle of the crossbar. If you twist at one of the outer arms, you will not get accurate results. Just push on the arm at the point where the cable meets it, so that you are applying the same force that the cable does when it pulls. If you put your hand on the crossbar and twist it using your thumb or something on the middle arm, you are still applying a force that the crossbar will not experience under normal conditions.

Watch the throttles, and compare what both sides are doing. They should be opening at the same exact moment. Realize that as the engine warms up the geometry changes slightly so there may be some difference between hot and cold engine. I like to warm mine up before I do this. After you get them synched right, tighten down the nuts so that both the heim joints are centered to their positions. I rotate the joints so that they are both resting against the position they would be pulled to when you tighten the nuts, and then I tighten them. Be sure to not let the rod twist when you position or tighten them. You may find that tightening the nuts changes the geometry slightly, so you may have to compensate a little bit for this on the rod.

After you get the nuts tight, check it again, and repeat if necessary.

Why this matters so much: Once you get them synched perfect, you will FEEL how much better it runs, especially on low throttle lower RPM. If you have a head temperature gauge, you will see that when the linkage is not right, one side will run warmer than the other. If the left side throttle opens first, the left side will run warmer, especially at low throttle low RPMs.

The last thing you should do if you have never done it: Loosen the throttle cable from the center arm and have someone push the gas pedal to the floor. Pull the cable tight, and then snug the connector. This will ensure that you do not put undue stress on the throttle shafts on the carbs at full throttle. If you put too much pressure on them you can twist the throttle shafts too much and bend them. This is especially true of setups that have the return spring and stop on the FRONT of one of the carbs, which is the way most Weber setups are out of the box. I use the CB Weblink kit to put the springs both on the throttle linkage side, to help with synchronization.

This with some practice and a good feel for what you are doing will help a lot with making sure your engine runs smooth.

Drive it
Something you should understand about tuning from this point. Your accelerator pumps are going to try to fool you unless you understand their purpose and function.

Accelerator pumps are there to compensate for some physics. The fact is that fuel is heavier than air, and it takes longer for the fuel to pick up speed in the circuits than it does for the air to pick up speed in the throats. So when you stomp the gas, the air starts moving faster a lot sooner than the fuel does. The accelerator pumps are there to provide a little extra fuel during that short time it takes for the fuel to catch up. Keep this in mind when you are tuning the jets, and avoid rapid pedal movements for now.

It really helps to have a tach, and an air fuel gauge, and I would say that a tach is next to necessary, while an air fuel gauge is a luxury that you can do without unless you are FINE tuning, and going for near perfect in terms of mileage and power.

Take the car out and drive it. Pay attention to what's going on at about 1500 to 2000 RPM, and at 2000 to 3000 RPM, and from 3000 to 4000 RPM. While the RPM bands will vary depending on what size carbs, what vents, and what engine combo you have, these are pretty safe ranges to look at.

1500 to 2000 RPM is almost purely idle jets in action. Keep the pedal steady here, in 3rd gear so you can see what it does with a slight load. If this area is running ok, move on. If it feels weak or soggy, you might need different idle jets. Unfortunately, it's sometimes hard to tell if it's rich or lean unless you are experienced here. This is where an air fuel meter will help you out. What you can try is opening up your mixture screws about half turn and see if it feels better. If it doesn't, then it might be too rich. If it does, then your idle jets may be too lean. For those of you with air-fuel gauges, about 13-13.5 or so is what I like. Move on to the next range.

2000 to 3000 RPM is the "transition" stage. This is the part where the main circuit starts to take over. Your idle jets start to matter less here, and your air corrector jets are the progressively deciding factor for why your engine is running the way it is. With the pedal steady, make note of how it feels in here, and move on.

3000 to 4000 RPM is where your main jets are really doing their job. With the pedal steady, if it feels lean here, (sort of like it is running out of fuel) then you might want to try going up a main jet size. If not, try going down one and see how it runs. Go down until it starts to feel lean (weaker with maybe some popping). When you feel it go lean, move back up a size and you are done with the mains. For those of you with air-fuel gauges, about 13.0 - 13.5 or so is what I like.

Now, back to the transition stage. If it felt lean there before you did anything, and the main circuit felt lean, determine of moving the main jet up helped the transition stage. When the idles and mains are both right, the transition should be pretty good too. If your mains and your idles feel good, but your transition does not, try going up a couple sizes on the air jet and see if that helps. If not, try to go up a couple sizes more and see. By now you should have it cleaned up. If you STILL have problems with transition, something else may be wrong. Read the article to the left about transition.

Accelerator pump settings
Once everything else feels right at steady state, then you can start playing with the accelerator pumps. While there are different pump jets and bypass valves, you can usually get what you need out of the ones that come on the carbs out of the box. First, make sure that they are adjusted the same. Drive it, and see what happens when you give it gas more quickly. If when you are in second or third gear, and you push the pedal from cruise to WOT over the course of about a half second, and it bogs, try unscrewing each accelerator pump nut about 3 turns and try it again. If it's worse, then they were too lean, and you should go back the other way. Try 3 turns at a time until they are right. You shouldn't need more than about 1/2" of rod sticking out of the nut. If you do, you might have some timing issues you need to deal with. For those of you with an air-fuel meter, your meter's response to mashing the pedal should be as close to steady as possible, but that's not realistic to expect. If your engine falls on its face, and the meter goes lean, screw the nuts in about three turns on each side, and try again. Same rules for if it goes rich for any period of time, like two seconds or so. What I like to do is back off the screws until it falls on its face, and then start screwing them back in until it doesn't anymore. Too much fuel from the accelerator pumps is going to cause the excess fuel to wash oil off the cylinders, and cause you poor mileage.

Common mistakes
Lots of folks are driving around thinking their state of tune is good, when in fact, they've covered up symptoms with incorrect jetting. The only ONLY way to know for sure is to have an accurate air/fuel meter, but you can avoid a lot of it by just paying close attention to what the different circuits are doing. For dialing the jets, paying attention to what happens as you mash the pedal or right afterwards is wrong. The accelerator pump is screwing with things when you do that. Jetting requires paying attention to what's happening at steady state, during fixed RPM ranges, under different conditions.

What happens under WOT is not an ideal way to assess your jetting, at least under heavy load and at lower RPM ranges. Things will go rich there, and should due to what your engine needs. If you have an Air/Fuel meter and it is dropping down to the 11's or something when you nail it, worry about some of that when you have the rest tuned. Don't shoot for getting that right until you get the rest right. That part may never be perfect, but you can get it closer after you do the rest.

If you think you have it tuned, drive it for a while, a distance, a few days, whatever, and see how you feel about it. If you try to jet an engine that has been running really rich for a while, it may take a few stages of leaning it before you get it right, due to carbon buildup, and may take some new plugs to be sure. Plugs are another factor that has to be paid sufficient heed to get things right. That's another topic, but about 0.025" for stock, more like 0.040" for CDI and such.

New engines: Never try to tune a new engine perfectly. It's going to change. I tend to suggest running them a little rich in the beginning to keep temps down and make sure you don't lean it out while your rings are trying to seat.

What kind of mileage should you expect? Depends on how you drive. If you drive it like you're sick of the high gas prices you should get close to 20 if everything is right, maybe even more. I get about 25. You can get very good mileage if you lean things out close to 14 across the board, reduce your accelerator pump action to the very minimum, with just a hint of hesitation when you punch it, and use a vacuum advance distributor (SVDA) with the ports on the carbs (many have vacuum ports you can attach to a T fitting and then to an SVDA distributor that is tuned right for use with dual carbs. Not all cam/head setups are going to work well with an SVDA distributor, but many will do fine.

If you drive with a heavy foot, then face facts. Your mileage is going to suck.

Hope this helps you.


____________________________________________________________________________________________________
Spa parts:DIY Hot Tub Repair and It's all about Spas
How to post images [You must be registered and logged in to see this link.]
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]


Last edited by K1 on 6/1/2012, 7:11 pm; edited 2 times in total
Back to top Go down
K1
Admin
Admin


Location: in the back shed

PostSubject: Re: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   11/25/2011, 11:03 pm

Weber Jetting Chart
This Jetting Chart provides a base line starting point. Every engine responds differently, and final jetting changes are most often determined by the engine builder or tuner. Engine size, cam, cylinder heads, ignition system, compression ratio, exhaust system, type of fuel, the vehicle and type of driving are all key elements in final calibration. The selection of main gas and air correction jets is determined by venturi size. The venturi sizes listed below are the sizes supplied by Weber in new carburetors. The use of larger venturi will increase airflow, and larger main gas jets than noted below will be required.
WEBER 40 IDF
Factory
Sizes

Single
Carb

Dual
Carbs

AIR CORRECTION
2.00
1.60
2.00
EMULSION TUBE
F-11


MAIN JET
1.15
1.45
1.30
PUMP JET
.50
.80
.50
IDLE JET
.50
.65
.55
VENTURII
28mm


NOTE: Drill 2mm Hole in each Throttle Valve of Single Carb.

WEBER 44 IDF
Factory
Sizes
Single
Carb
Dual
Carbs
AIR CORRECTION
1.75
1.65
2.00
EMULSION TUBE
F-11


MAIN JET
1.35
1.60
1.55
PUMP JET
.50
.80
.50
IDLE JET
.50
.65
.60
VENTURII
36mm


NOTE: Drill 2mm Hole in each Throttle Valve of Single Carb.

WEBER 48 IDF
Factory
Sizes
Single
Carb
Dual
Carbs
AIR CORRECTION
1.80
1.80
2.00
EMULSION TUBE
F-2


MAIN JET
1.50
1.70
1.75
PUMP JET
.50
.80
.50
IDLE JET
.55
.65
.60
VENTURII
40mm


NOTE: Drill 2mm Hole in each Throttle Valve of Single Carb.

WEBER 34 ICT
Factory
Sizes
Single
Carb
Dual
Carbs
AIR CORRECTION
1.60
N/A
1.60
EMULSION TUBE
F-78
N/A

MAIN JET
1.30
N/A
1.35
PUMP JET
.50
N/A
.50
IDLE JET
.52
N/A
.60
Weber Carburetor Parts
NOTE: Please specify exact sizes when ordering Jets & Venturi.
IDF Idle
Jets
#6394
IDF Main
Gas Jets
#6398
IDF Air
Correction Jets
#6389
IDF Carburetor
Base Gaskets
40 #6398 /
44 #2709 /
48 #2702
IDF Carburetor Rebuild
Kit (40, 44, & 48)
#6362
[You must be registered and logged in to see this image.]
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]
[You must be registered and logged in to see this image.]
[You must be registered and logged in to see this image.]
DCOE Idle
Jets
#6451
DCOE Main
Gas Jets
#6398
DCOE Air
Correction Jets
#6389
DCOE Carburetor
Base Gasket
40 #2705
45-48 #2702
DCOE Carburetor
Rebuild Kit
(40, 45 & 48)#6364
Not
Available
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.][You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]
DCNF Idle
Jets
#6450
DCNF Main
Gas Jets
#6399
DCNF Air
Correction Jets
#6390
DCNF Carburetor
Base Gasket
#2739
DCNF Carburetor
Rebuild Kit
(40, 42, & 48)#6361
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]Not
Available
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]
IDA Idle
Jets
#6357
IDA Main
Gas Jets
#6398
IDA Air
Correction Jets
#6389
IDA Carburetor
Base Gasket
#2701
IDA Carburetor Rebuild Kit - 48
#6363
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.][You must be registered and logged in to see this image.][You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]
Emulsion Tubes
[You must be registered and logged in to see this image.]
F-2
#6353

44 IDF Venturi
[You must be registered and logged in to see this image.]
40 IDF
Venturi
#6395

44 IDF
Venturi
#6356
[You must be registered and logged in to see this image.]
Carburetor
Flow Meter
F-7
#6352

F-11
#6354

____________________________________________________________________________________________________
Spa parts:DIY Hot Tub Repair and It's all about Spas
How to post images [You must be registered and logged in to see this link.]
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]


Last edited by K1 on 11/25/2011, 11:34 pm; edited 1 time in total
Back to top Go down
K1
Admin
Admin


Location: in the back shed

PostSubject: Tuning the 009 Distributor/34 PICT Carburetor Combination   11/25/2011, 11:18 pm

Someone wrote with problems with the 34 PICT/3 carburetor on his 1600cc twin-port engine (new manifold boots and gaskets, new plugs and leads, 009 centrifugal-advance distributor). I have read lots on the common “flat spot” problem (stumbling at low-rpm acceleration) and have tried the adjustments, but I still have the flat spot. I have opened up carburetor and checked the float, needle valve and seat — all okay. I also cleaned and blew out all visible rubbish. The motor seems to idle okay, but it spits and coughs when accelerating. If I up the size of the main jet and idle jet by one size or two will this help?
Parts you might need - link to category Ignition System

[You must be registered and logged in to see this image.]


Rob responded – Carburetor troubles can be related to all sorts of things — fouled plugs, bad plugs, bad or weak coils, blocked fuel filters, damaged accelerator pump diaphragm, etc., etc. But a significant source of “flat spot” trouble stems from the combination of the 34 PICT/3 carburetor and the 009 centrifugal-advance distributor.
Someone wrote with a suggestion that many people try, but we don’t recommend. Here’s what he says to do to get rid of the “flat spot – The answer to your problem is simple. If you don’t care about fuel consumption too much, run a 1/16th drill bit through the main jet. Try it as it works, and easy to get another jet if you don’t like the fuel consumption. And as for your 009 distributor, if you see a 050 for sale BUY it.
Rob responded to the jet drilling suggestion – I hope that “1/16th drill” wasn’t serious??? That’s X158.75 in Solex jet size equivalent!!! The normal jet size for a 34PICT/3 with vacuum distributor is X127.5 and with a 009 distributor is X130 or X132.5 at most. With an X158.75 main jet you’d have about 24% increase in fuel consumption!
The guy responded (paraphrased) – Yes, my suggestion to drill the main jet with a 1/16″ drill was serious. As I said, if you don’t care for the fuel consumption you will find that it works. Try it — its only a jet.
Rob – I wonder if you realize just how BIG 1/16th is (hence the Solex size equivalent I noted.) If drilled to 1/16th” the jet will supply so much excess fuel that you’ll have…
About 24% increase in fuel consumption — worse than the average Holden V8.
Serious plug fouling.
Serious wash-down of the oil film on the cylinder walls, resulting in massively increased wear.
Oil dilution and contamination (more wear).
Smokey exhaust (the cops may be interested).
Need I go on?
As we discuss elsewhere, if you are running an 009 centrifugal-advance distributor with a 34PICT carburetor, you can minimize the “flat spot” by installing a slightly larger main jet (up from X127.5 to X130 or X132.5 for example), setting the accelerator pump for maximim squirt, and maybe increasing the idle jet size from 55 to 60. Then set the maximum distributor advance to as much of the 28-32 degrees BTDC as it can take without the engine detonating/pinging.
Some have recommended filling in the throttle valve bleed hole. This should only be tried if the above modifications don’t eliminate the flat spot. Doing so results in the carburetor running extra rich at low and middle speeds (butterfly closed or slightly open), as it allows more air to “leak” through the throat without sucking in fuel. So filling the hole mean less air for the same fuel pulled through the jets. It won’t harm the engine any more than other run-rich methods needed to work with the 009 distributor, but if you expect the engine to last a long time then be aware that running rich (which you NEED to do with the 009), results in oil wash-down in the cylinders which will speed piston ring wear somewhat.

____________________________________________________________________________________________________
Spa parts:DIY Hot Tub Repair and It's all about Spas
How to post images [You must be registered and logged in to see this link.]
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]
Back to top Go down
the-jerm
Crew Chief
Crew Chief


Location: Sorrysota physically, lost mentally

PostSubject: Re: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   11/26/2011, 11:38 pm

Holy sh!t! That's a lot of info. Shocked
Someone's been busy. Thanks for sharing it!
I'll definitely have to read this when i'm not half asleep Laughing
Back to top Go down
mharney
Newbie / Rebuilding engine
Newbie / Rebuilding engine



PostSubject: Re: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   5/25/2012, 4:44 pm

The first entry in this thread was taken directly from my site at carburetorclinic.com, and is my article. If you want to post information from someone else's site, it's good policy to cite your reference. Smile Thanks.
Back to top Go down
U B BUGN
Crew Chief
Crew Chief


Location: WORKIN' IN NAPLES, YUCK!!!

PostSubject: Re: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   5/25/2012, 10:39 pm

Which one is that.......The one with all the weiners?
[You must be registered and logged in to see this image.]
Back to top Go down
K1
Admin
Admin


Location: in the back shed

PostSubject: Re: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   5/27/2012, 2:39 pm

mharney wrote:
The first entry in this thread was taken directly from my site at carburetorclinic.com, and is my article. If you want to post information from someone else's site, it's good policy to cite your reference. Smile Thanks.
Your right ur site should of been mentioned sorry about that. Great write up And very useful

____________________________________________________________________________________________________
Spa parts:DIY Hot Tub Repair and It's all about Spas
How to post images [You must be registered and logged in to see this link.]
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]
Back to top Go down
mharney
Newbie / Rebuilding engine
Newbie / Rebuilding engine



PostSubject: Re: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   6/1/2012, 4:03 pm

U B BUGN wrote:
Which one is that.......The one with all the weiners?
[You must be registered and logged in to see this image.]

Indeed, those are in fact hot links..the image that is put up when people try to hot link.
Back to top Go down
K1
Admin
Admin


Location: in the back shed

PostSubject: Re: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   6/1/2012, 7:14 pm

Hey what happen to the wieners?? mharney notice the first line?

____________________________________________________________________________________________________
Spa parts:DIY Hot Tub Repair and It's all about Spas
How to post images [You must be registered and logged in to see this link.]
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]
Back to top Go down
U B BUGN
Crew Chief
Crew Chief


Location: WORKIN' IN NAPLES, YUCK!!!

PostSubject: Re: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   6/2/2012, 1:15 pm

Way to step up K1. I have gotten some good info from that site before. Glad there is a link to it now.

However all this talk about Weiners and Hot Links has me hungry...... Time to FIRE UP THE GRILL!!!!

lol!
Back to top Go down
mharney
Newbie / Rebuilding engine
Newbie / Rebuilding engine



PostSubject: Re: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   6/2/2012, 4:54 pm

K1 wrote:
Hey what happen to the wieners?? mharney notice the first line?

I did.. Thanks for that.

The weiners were offline for a spell.. moved and my webserver moved with me. The weiners are back. I will add you to the list of hot link exceptions. They should be replaced with real pics.
The page architecture has changed though, and your code points to an image that no longer exists. I guess I shot myself in the foot, because if you had been allowed hot link graphics by my webserver, that site name woulda ben there. I guess I could exception that image. lol

--Mark
Back to top Go down
K1
Admin
Admin


Location: in the back shed

PostSubject: Re: Tuning Dual Weber IDF Carbs on the VW Type 1 Engine   6/3/2012, 12:17 am

Thanks Mark for the use of a great write up Smile

____________________________________________________________________________________________________
Spa parts:DIY Hot Tub Repair and It's all about Spas
How to post images [You must be registered and logged in to see this link.]
[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]
Back to top Go down
 

Tuning Dual Weber IDF Carbs on the VW Type 1 Engine

View previous topic View next topic Back to top 
Page 1 of 1

 Similar topics

-
» Pro-To-Type
» a topic on oko or pwk flatslide carbs
» Invicta SAS, Croton Dual Dial - Let's move some watches
» Guide To Tuning The 3SGE
» Bytetronik MINIFlash FullAccess Tuning Software for the R53 (brief intro)

Permissions in this forum:You cannot reply to topics in this forum
Tampa VW ::  :: -



Free forum | © phpBB | Free forum support | Contact | Report an abuse | Free forums
Hot Tub Parts | TampaVW FaceBook