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mikedjames
Samba Member
Joined: July 02, 2012
Posts: 2743
Location: Hamble, Hampshire, UK
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 Posted: Thu Aug 27, 2015 10:02 am Post subject: |
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| GBHgpJON wrote: |
Tried this question a week ago, as a seperate title with no luck, so thought I'd try it on this topic.
I'm getting a rise in the revs when spraying carb cleaner around where the preheat pipes enter the manifold while searching for an airleak. Admittedly they aren't the best fit, but I didn't think these passageways are connected directly to the intake? Anyone care to enlighten me......weber progressive aircooled.net manifold. Cheers. |
The heater tubes are not connected to the inlet manifold.
I would think your ar leak is the manifold rubber boots as they are nearby or you have some problem at the carburettor base .. Damaged gasket or maybe a hidden manifold vacuum takeoff that is not connected.
_________________
Ancient vehicles and vessels
1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.
1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy |
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Thu Aug 27, 2015 10:02 am Post subject: |
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They are not supposed to be, but about 5% of the intakes have porosity (a leak) between the intake and preheat chambers.
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mikedjames
Samba Member
Joined: July 02, 2012
Posts: 2743
Location: Hamble, Hampshire, UK
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| Posted: Thu Aug 27, 2015 10:03 am Post subject: |
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| GBHgpJON wrote: |
Tried this question a week ago, as a seperate title with no luck, so thought I'd try it on this topic.
I'm getting a rise in the revs when spraying carb cleaner around where the preheat pipes enter the manifold while searching for an airleak. Admittedly they aren't the best fit, but I didn't think these passageways are connected directly to the intake? Anyone care to enlighten me......weber progressive aircooled.net manifold. Cheers. |
The heater tubes are not connected to the inlet manifold.
I would think your ar leak is the manifold rubber boots as they are nearby or you have some problem at the carburettor base .. Damaged gasket or maybe a hidden manifold vacuum takeoff that is not connected.
_________________
Ancient vehicles and vessels
1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.
1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy |
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GBHgpJON
Samba Member
Joined: March 10, 2007
Posts: 73
Location: North Devon, England..........
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| Posted: Fri Aug 28, 2015 3:11 am Post subject: |
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| [email protected] wrote: |
| They are not supposed to be, but about 5% of the intakes have porosity (a leak) between the intake and preheat chambers. |
Money well spent then.......and I hasten too add it wasn't bought from Aircooled.net.
If this is the case, fuel tank sealer comes to mind?...... |
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Fri Aug 28, 2015 7:44 am Post subject: |
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I have had customers that sealed their intake with fuel tank sealer prior to installation to prevent any issues before they happened, and a couple that fixed leaks this way. It works fine.
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GBHgpJON
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Joined: March 10, 2007
Posts: 73
Location: North Devon, England..........
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| Posted: Fri Aug 28, 2015 8:55 am Post subject: |
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| OK....That's good to know.......out of interest, did they seal both preheat and inlet sides for good measure? |
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Fri Aug 28, 2015 8:56 am Post subject: |
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no, just the intake side. I'm not sure the preheat side would take the heat anyways. If it's sealed it's sealed.
_________________
It's just advice, do whatever you want with it!
Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net
"Like" our Facebook page at
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and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net |
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GBHgpJON
Samba Member
Joined: March 10, 2007
Posts: 73
Location: North Devon, England..........
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| Posted: Fri Aug 28, 2015 9:11 am Post subject: |
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Yeah....that makes sense. Thanks for your help, its appreciated.  |
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GBHgpJON
Samba Member
Joined: March 10, 2007
Posts: 73
Location: North Devon, England..........
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| Posted: Wed Sep 09, 2015 11:35 am Post subject: |
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Early signs are good, seems the tank sealer has done the job! Tune up fun starts now.
Thanks all..... |
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spencerfvee
Samba Member
Joined: August 19, 2004
Posts: 3071
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| Posted: Sun Oct 02, 2016 12:32 pm Post subject: Re: How to make a progressive work properly on a VW engine. |
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john I know this is a old post .today I jetted my weber carb .with the jetting you posted .it realy woke up my 1600cc motor thanks spencerfvee
| [email protected] wrote: |
I may edit this as needed, if I've overlooked anything, or need to make a change. If you have a question, ask in the reply and I'll edit the Original Post to clarify.
MAKING PROGRESSIVES WORK
If you have an EMPI progressive, you got hosed. Get a real Weber DFAV/DFEV.
Don't run a 009 or other centrifugal only distributor. They suck! Run our SVDA, it will make your tuning job MUCH easier. Good progressive carbs HAVE the proper port for the SVDA, if they do not you got a chinese copy or an old (ie: obsolete) progressive, and you will HAVE no other choice but to run a 009/010, but you will NOT have optimal tuning results like you would if you had a SVDA.
Centermount Progressives NEED intake heat, and lots of it. This is why a progressive on a T4 WILL NOT WORK. It's so bad and unfixable, we do not even sell the kits that are available for the T4. It will not work, do not ask, because the answer is "get dual carbs". Nuff' Said.
On a T1, the stock muffler is setup perfect, just make sure they are clear. But if you have an aftermarket header with the flanges on #2 and #4 primaries, you must relocate one of them to the collector (like the stock muffler!) to get good preheat. Don't be a lazy ass and think you are special and that these rules don't apply to you. Just relocate one to the collector, with some small steel tubing, and weld/braze it in place. Or have the guy at the muffler shop do it, it's an easy job for him.
If you don't do this relocation modification, don't bitch about the flat spot and poor MPG, along with needing "wack" jetting (like a richer primary than what I use). The intake preheat keeps the fuel that is metered at the carburetor (by the idle and main jets) VAPORIZED (Google "Latent Heat of Vaporization"). Your intake heat is of a fixed amount. The richer it is, the colder the intake is going to be. Don't be any richer than you have to! If the intake is cold, you have to jet rich to make sure that the air/fuel reaching the cylinder is rich enough, because a lot of the metered fuel condensed on the way to the cylinder because it's cold (not vaporized), and a long ways from the carb to the cylinder. So you have fun stuff like when you rev it up, all that condensed liquid fuel puddled in the intake makes it's way into the cylinders and now you are way rich. Intake heat IS A GOOD THING for centermounts! Even if it's 120F in the desert, the intake heat is a good thing! The more heat you route to the intake, the leaner you will be able to jet the carb, and keep the A/F the same. If you have a wideband, you'll see that as you add heat to the intake, it will run richer, since you are keeping fuel vaporized and it will combust properly!
I've even recommended to some guys that didn't want to hack their exhaust to have simply routed their hot engine oil thru the preheat tubes, which has the double benefit of heating the intake and cooling the oil AT THE SAME TIME. If you have a porous intake (ie: CHEAP) you are SOL on this one, it will leak.
http://vwparts.aircooled.net/Deluxe-Center-Mount-Intake-Manifold-Kit-Weber-DFEV-p/99004-410b.htm is a good intake.
Also, good intakes route the heat to the carb base, NOT just along the bottom tube. If you see a bottom tube only preheat model, walk away from it, it sucks. PERIOD. A good intake is not that much, and solves the progression linkage issue also (the carb doesn't line up with the throttle cable. Cheap kits have a ghetto connection from cable to carb, that doesn't even open the carb all the way up at WOT. The good intake will fix the linkage issue, with a McGyver like arrangement on the manifold. It works very well.
I will also say that hot air intake also helps your cause. Figure a way to get hot air from under the engine, to the air intake on the carb.
All Webers also need 3-3.5psi fuel pressure, and the floats set to spec. They are NOT SET when new, so learn to work on the carburetor! These 4 things (fuel pressure, float level, intake heat, hot air intake) are NOT done by 99% of progressive owners, and the cause of the bad rap.
The next issue is jetting. I have not once, in 30 years of working on these things, seen a progressive properly jetted, not even CLOSE, if I haven't worked on it first. I have also never seen a store that properly jet a progressive. Their "charts and guidelines" are horrible. HORRIBLE. It's like they want you to blow up your engine and wear out your rings/pistons from fuel washdown, in 5k miles. So, on we go.
Here are my guidelines for progressive jetting.
Primary idle, 45-50 at sea level, 40-45 @ 5k'. Secondary idle 10-15 larger than primary idle. Weber supplies them with the primary idle larger than the secondary, WHICH IS STUPID. It runs too rich on the primary, then leans out when the secondary opens.
The more intake preheat you have, the smaller your idle jetting will need to be, since the fuel metered by the jet actually stays vaporized, it's not puddling and condensing.
Main jet. 125 primary. 180-190 secondary (not a misprint). I've even seen some engines need 210 secondary mains. If you do not stagger your secondary jetting, you WILL have the same problem of severe lean out when the secondary opens up, since airspeed drops so much due to air flowing thru 2 bbls. You want to be lean on the primary (for mpg and cool running), but richen up to 13:1 when the secondary opens. Most clowns jet the primary and secondary the same. So when airspeed drops to <1/2 when the secondary opens, the vac signal the main circuit sees is also < halved, and your pride and joy leans out like crazy. This is why the secondary main MUST be much larger than the primary main. I'd like to slap the morons that recommends square jetting on the main jets. They are clueless.
Air jets. 160-180 will work, I generally use 160 on primary, and 180 on secondary. If you use a 180 secondary air, you may need to go up 10 more on the main, to a 190-200 secondary main. Do NOT be scared of the "huge" secondary jet, it WILL WORK PROPERLY. I've setup hundreds of these carbs, and know what works and why.
If you are at elevation, for every 4k'
drop both idles 5
drop both mains 5
increase airs 10-15.
These guidelines will work for a heated intake, properly setup carb (float, fuel pressure), with no ignition "issues".
Sea Level, run 45/60, 125/190, 160/180
@4-5K', run 45/55, 120/180, 175/190
@8k', run 40/55, 115/175, 190/205.
I even saw one guy at 8'k that needed a 37.5 primary idle.
If you do not have the intake heated, your jetting will have to be much richer than this, for reasons mentioned previously.
These guidelines are not exact, but VERY close.
I hope this helps. E-mail me directly (please do NOT use PMs, I do not check these) and I'll help further. Please have the basics covered first (fuel pressure, floats, ignition, etc), because that's the first thing I'm going to address, and if you do not I cannot help you.
John
Aircooled.Net Inc. |
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spencerfvee
Samba Member
Joined: August 19, 2004
Posts: 3071
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| Posted: Sun Oct 02, 2016 12:36 pm Post subject: Re: How to make a progressive work properly on a VW engine. |
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john I never realy like the weber progressive carb but I found a NOS one and needed a carb for my 1600cc motor .your jetting is right on motor runs great thanks spencer
| [email protected] wrote: |
I may edit this as needed, if I've overlooked anything, or need to make a change. If you have a question, ask in the reply and I'll edit the Original Post to clarify.
MAKING PROGRESSIVES WORK
If you have an EMPI progressive, you got hosed. Get a real Weber DFAV/DFEV.
Don't run a 009 or other centrifugal only distributor. They suck! Run our SVDA, it will make your tuning job MUCH easier. Good progressive carbs HAVE the proper port for the SVDA, if they do not you got a chinese copy or an old (ie: obsolete) progressive, and you will HAVE no other choice but to run a 009/010, but you will NOT have optimal tuning results like you would if you had a SVDA.
Centermount Progressives NEED intake heat, and lots of it. This is why a progressive on a T4 WILL NOT WORK. It's so bad and unfixable, we do not even sell the kits that are available for the T4. It will not work, do not ask, because the answer is "get dual carbs". Nuff' Said.
On a T1, the stock muffler is setup perfect, just make sure they are clear. But if you have an aftermarket header with the flanges on #2 and #4 primaries, you must relocate one of them to the collector (like the stock muffler!) to get good preheat. Don't be a lazy ass and think you are special and that these rules don't apply to you. Just relocate one to the collector, with some small steel tubing, and weld/braze it in place. Or have the guy at the muffler shop do it, it's an easy job for him.
If you don't do this relocation modification, don't bitch about the flat spot and poor MPG, along with needing "wack" jetting (like a richer primary than what I use). The intake preheat keeps the fuel that is metered at the carburetor (by the idle and main jets) VAPORIZED (Google "Latent Heat of Vaporization"). Your intake heat is of a fixed amount. The richer it is, the colder the intake is going to be. Don't be any richer than you have to! If the intake is cold, you have to jet rich to make sure that the air/fuel reaching the cylinder is rich enough, because a lot of the metered fuel condensed on the way to the cylinder because it's cold (not vaporized), and a long ways from the carb to the cylinder. So you have fun stuff like when you rev it up, all that condensed liquid fuel puddled in the intake makes it's way into the cylinders and now you are way rich. Intake heat IS A GOOD THING for centermounts! Even if it's 120F in the desert, the intake heat is a good thing! The more heat you route to the intake, the leaner you will be able to jet the carb, and keep the A/F the same. If you have a wideband, you'll see that as you add heat to the intake, it will run richer, since you are keeping fuel vaporized and it will combust properly!
I've even recommended to some guys that didn't want to hack their exhaust to have simply routed their hot engine oil thru the preheat tubes, which has the double benefit of heating the intake and cooling the oil AT THE SAME TIME. If you have a porous intake (ie: CHEAP) you are SOL on this one, it will leak.
http://vwparts.aircooled.net/Deluxe-Center-Mount-Intake-Manifold-Kit-Weber-DFEV-p/99004-410b.htm is a good intake.
Also, good intakes route the heat to the carb base, NOT just along the bottom tube. If you see a bottom tube only preheat model, walk away from it, it sucks. PERIOD. A good intake is not that much, and solves the progression linkage issue also (the carb doesn't line up with the throttle cable. Cheap kits have a ghetto connection from cable to carb, that doesn't even open the carb all the way up at WOT. The good intake will fix the linkage issue, with a McGyver like arrangement on the manifold. It works very well.
I will also say that hot air intake also helps your cause. Figure a way to get hot air from under the engine, to the air intake on the carb.
All Webers also need 3-3.5psi fuel pressure, and the floats set to spec. They are NOT SET when new, so learn to work on the carburetor! These 4 things (fuel pressure, float level, intake heat, hot air intake) are NOT done by 99% of progressive owners, and the cause of the bad rap.
The next issue is jetting. I have not once, in 30 years of working on these things, seen a progressive properly jetted, not even CLOSE, if I haven't worked on it first. I have also never seen a store that properly jet a progressive. Their "charts and guidelines" are horrible. HORRIBLE. It's like they want you to blow up your engine and wear out your rings/pistons from fuel washdown, in 5k miles. So, on we go.
Here are my guidelines for progressive jetting.
Primary idle, 45-50 at sea level, 40-45 @ 5k'. Secondary idle 10-15 larger than primary idle. Weber supplies them with the primary idle larger than the secondary, WHICH IS STUPID. It runs too rich on the primary, then leans out when the secondary opens.
The more intake preheat you have, the smaller your idle jetting will need to be, since the fuel metered by the jet actually stays vaporized, it's not puddling and condensing.
Main jet. 125 primary. 180-190 secondary (not a misprint). I've even seen some engines need 210 secondary mains. If you do not stagger your secondary jetting, you WILL have the same problem of severe lean out when the secondary opens up, since airspeed drops so much due to air flowing thru 2 bbls. You want to be lean on the primary (for mpg and cool running), but richen up to 13:1 when the secondary opens. Most clowns jet the primary and secondary the same. So when airspeed drops to <1/2 when the secondary opens, the vac signal the main circuit sees is also < halved, and your pride and joy leans out like crazy. This is why the secondary main MUST be much larger than the primary main. I'd like to slap the morons that recommends square jetting on the main jets. They are clueless.
Air jets. 160-180 will work, I generally use 160 on primary, and 180 on secondary. If you use a 180 secondary air, you may need to go up 10 more on the main, to a 190-200 secondary main. Do NOT be scared of the "huge" secondary jet, it WILL WORK PROPERLY. I've setup hundreds of these carbs, and know what works and why.
If you are at elevation, for every 4k'
drop both idles 5
drop both mains 5
increase airs 10-15.
These guidelines will work for a heated intake, properly setup carb (float, fuel pressure), with no ignition "issues".
Sea Level, run 45/60, 125/190, 160/180
@4-5K', run 45/55, 120/180, 175/190
@8k', run 40/55, 115/175, 190/205.
I even saw one guy at 8'k that needed a 37.5 primary idle.
If you do not have the intake heated, your jetting will have to be much richer than this, for reasons mentioned previously.
These guidelines are not exact, but VERY close.
I hope this helps. E-mail me directly (please do NOT use PMs, I do not check these) and I'll help further. Please have the basics covered first (fuel pressure, floats, ignition, etc), because that's the first thing I'm going to address, and if you do not I cannot help you.
John
Aircooled.Net Inc. |
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Sun Oct 02, 2016 6:29 pm Post subject: Re: How to make a progressive work properly on a VW engine. |
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That's great to hear Spencer, good news! They work ok for what they are, and if you know their limitiations.
_________________
It's just advice, do whatever you want with it!
Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net
"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50352
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| Posted: Sun Oct 02, 2016 6:56 pm Post subject: Re: How to make a progressive work properly on a VW engine. |
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| [email protected] wrote: |
| That's great to hear Spencer, good news! They work ok for what they are, and if you know their limitiations. |
John, have your tried blocking off the fuel flow to the high speed enrichment on the secondaries? I did this on my Type 4 while jetting the secondaries a bit richer (about 12:1 at sea level for both barrels combined). Helps with the transition to the secondaries without the mixture getting needlessly rich during full throttle high speed operation. I just drilled and tapped the passage in the body leading up to the port in the cover and installed a set screw to act as a plug. Remove the set screw/plug and the modification is reversed with no ill effects. |
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[email protected]
Samba Member
Joined: August 03, 2002
Posts: 12785
Location: Salt Lake City, Utah
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| Posted: Sun Oct 02, 2016 7:58 pm Post subject: Re: How to make a progressive work properly on a VW engine. |
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every time I've looked at this carb, it's too rich at low throttle settings (primary), and too lean on the secondaries.
_________________
It's just advice, do whatever you want with it!
Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net
"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50352
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| Posted: Sun Oct 02, 2016 8:40 pm Post subject: Re: How to make a progressive work properly on a VW engine. |
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| [email protected] wrote: |
| every time I've looked at this carb, it's too rich at low throttle settings (primary), and too lean on the secondaries. |
I will agree on both counts to a certain extent.
-When you first give it throttle it tends to be lean as it comes off the idle system, yet once you are going down the road in the higher gears and the vacuum drops the power valve opens and causes a rich condition. Still more as you close the throttle down and the vacuum picks up it begins to draw on both the main system and the idle system at the same time again causing a rich condition.
-If you jet the secondaries rich enough that you don't get a drop in power as they open (for the reasons given in your own post) then once the airflow through the secondaries gets nice and high and fuel is drawn through the high speed enrichment system it will run too rich.
-I have pretty much figured out how to take care if everything except the carb running rich on the primaries when the primary throttle is less than 1/4 of the way open and fuel is being drawn through both the main system and the idle system at the same time. This dilemma of fuel entering the airflow from two different sources is probably why VW switched to the idle system used on the 34pict3 carb. |
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spencerfvee
Samba Member
Joined: August 19, 2004
Posts: 3071
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| Posted: Tue Oct 04, 2016 10:34 am Post subject: Re: How to make a progressive work properly on a VW engine. |
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hi john again thanks john .the only thing I had to do was go to a bigger on the needle and seat . I went to a 200 needle and seat. the stock one was a 175 needle seat . at wide open. it missed from not enough fuel . I ended up with a 165 air 130 main. I feal I can go lower on the main jet to a 125. I used a 180 air 180 main .your right the carb does have its limits on power .dual carbs would be better .but who realy needs to go over 85 mph now a days its just a 1600 cc motor with 40 by 35 valves engle 100 cam I got one speeding ticket this year I don't need any more lol ..it just a street motor again thank for the info .I am never to old to learn . and I hope that guys will understand how many years it took you to find out what works and what does not work .and all the hours you spent working on these carbs .a lot of guys just do not under stand how much work it takes to get a motor jetted . right. every motor is different thanks john jack spencer spencerfvee
| [email protected] wrote: |
| That's great to hear Spencer, good news! They work ok for what they are, and if you know their limitiations. |
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ScatKat1835
Samba Member
Joined: June 19, 2017
Posts: 1
Location: Farmington MI
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| Posted: Mon Jun 19, 2017 2:31 pm Post subject: Re: How to make a progressive work properly on a VW engine. |
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1st post been trolling for a while.
My ride
1835 Sand rail 32/36 progressive, heat tubes and Pertronix I SVDA, Flamethrower 1 coil.
I jetted to you suggestions OH BOY what a differance it runs like a scolded ape.
Thanks John and everyone's input.
| [email protected] wrote: |
I may edit this as needed, if I've overlooked anything, or need to make a change. If you have a question, ask in the reply and I'll edit the Original Post to clarify.
MAKING PROGRESSIVES WORK
If you have an EMPI progressive, you got hosed. Get a real Weber DFAV/DFEV.
Don't run a 009 or other centrifugal only distributor. They suck! Run our SVDA, it will make your tuning job MUCH easier. Good progressive carbs HAVE the proper port for the SVDA, if they do not you got a chinese copy or an old (ie: obsolete) progressive, and you will HAVE no other choice but to run a 009/010, but you will NOT have optimal tuning results like you would if you had a SVDA.
Centermount Progressives NEED intake heat, and lots of it. This is why a progressive on a T4 WILL NOT WORK. It's so bad and unfixable, we do not even sell the kits that are available for the T4. It will not work, do not ask, because the answer is "get dual carbs". Nuff' Said.
On a T1, the stock muffler is setup perfect, just make sure they are clear. But if you have an aftermarket header with the flanges on #2 and #4 primaries, you must relocate one of them to the collector (like the stock muffler!) to get good preheat. Don't be a lazy ass and think you are special and that these rules don't apply to you. Just relocate one to the collector, with some small steel tubing, and weld/braze it in place. Or have the guy at the muffler shop do it, it's an easy job for him.
If you don't do this relocation modification, don't bitch about the flat spot and poor MPG, along with needing "wack" jetting (like a richer primary than what I use). The intake preheat keeps the fuel that is metered at the carburetor (by the idle and main jets) VAPORIZED (Google "Latent Heat of Vaporization"). Your intake heat is of a fixed amount. The richer it is, the colder the intake is going to be. Don't be any richer than you have to! If the intake is cold, you have to jet rich to make sure that the air/fuel reaching the cylinder is rich enough, because a lot of the metered fuel condensed on the way to the cylinder because it's cold (not vaporized), and a long ways from the carb to the cylinder. So you have fun stuff like when you rev it up, all that condensed liquid fuel puddled in the intake makes it's way into the cylinders and now you are way rich. Intake heat IS A GOOD THING for centermounts! Even if it's 120F in the desert, the intake heat is a good thing! The more heat you route to the intake, the leaner you will be able to jet the carb, and keep the A/F the same. If you have a wideband, you'll see that as you add heat to the intake, it will run richer, since you are keeping fuel vaporized and it will combust properly!
I've even recommended to some guys that didn't want to hack their exhaust to have simply routed their hot engine oil thru the preheat tubes, which has the double benefit of heating the intake and cooling the oil AT THE SAME TIME. If you have a porous intake (ie: CHEAP) you are SOL on this one, it will leak.
http://vwparts.aircooled.net/Deluxe-Center-Mount-Intake-Manifold-Kit-Weber-DFEV-p/99004-410b.htm is a good intake.
Also, good intakes route the heat to the carb base, NOT just along the bottom tube. If you see a bottom tube only preheat model, walk away from it, it sucks. PERIOD. A good intake is not that much, and solves the progression linkage issue also (the carb doesn't line up with the throttle cable. Cheap kits have a ghetto connection from cable to carb, that doesn't even open the carb all the way up at WOT. The good intake will fix the linkage issue, with a McGyver like arrangement on the manifold. It works very well.
I will also say that hot air intake also helps your cause. Figure a way to get hot air from under the engine, to the air intake on the carb.
All Webers also need 3-3.5psi fuel pressure, and the floats set to spec. They are NOT SET when new, so learn to work on the carburetor! These 4 things (fuel pressure, float level, intake heat, hot air intake) are NOT done by 99% of progressive owners, and the cause of the bad rap.
The next issue is jetting. I have not once, in 30 years of working on these things, seen a progressive properly jetted, not even CLOSE, if I haven't worked on it first. I have also never seen a store that properly jet a progressive. Their "charts and guidelines" are horrible. HORRIBLE. It's like they want you to blow up your engine and wear out your rings/pistons from fuel washdown, in 5k miles. So, on we go.
Here are my guidelines for progressive jetting.
Primary idle, 45-50 at sea level, 40-45 @ 5k'. Secondary idle 10-15 larger than primary idle. Weber supplies them with the primary idle larger than the secondary, WHICH IS STUPID. It runs too rich on the primary, then leans out when the secondary opens.
The more intake preheat you have, the smaller your idle jetting will need to be, since the fuel metered by the jet actually stays vaporized, it's not puddling and condensing.
Main jet. 125 primary. 180-190 secondary (not a misprint). I've even seen some engines need 210 secondary mains. If you do not stagger your secondary jetting, you WILL have the same problem of severe lean out when the secondary opens up, since airspeed drops so much due to air flowing thru 2 bbls. You want to be lean on the primary (for mpg and cool running), but richen up to 13:1 when the secondary opens. Most clowns jet the primary and secondary the same. So when airspeed drops to <1/2 when the secondary opens, the vac signal the main circuit sees is also < halved, and your pride and joy leans out like crazy. This is why the secondary main MUST be much larger than the primary main. I'd like to slap the morons that recommends square jetting on the main jets. They are clueless.
Air jets. 160-180 will work, I generally use 160 on primary, and 180 on secondary. If you use a 180 secondary air, you may need to go up 10 more on the main, to a 190-200 secondary main. Do NOT be scared of the "huge" secondary jet, it WILL WORK PROPERLY. I've setup hundreds of these carbs, and know what works and why.
If you are at elevation, for every 4k'
drop both idles 5
drop both mains 5
increase airs 10-15.
These guidelines will work for a heated intake, properly setup carb (float, fuel pressure), with no ignition "issues".
Sea Level, run 45/60, 125/190, 160/180
@4-5K', run 45/55, 120/180, 175/190
@8k', run 40/55, 115/175, 190/205.
I even saw one guy at 8'k that needed a 37.5 primary idle.
If you do not have the intake heated, your jetting will have to be much richer than this, for reasons mentioned previously.
These guidelines are not exact, but VERY close.
I hope this helps. E-mail me directly (please do NOT use PMs, I do not check these) and I'll help further. Please have the basics covered first (fuel pressure, floats, ignition, etc), because that's the first thing I'm going to address, and if you do not I cannot help you.
John
Aircooled.Net Inc. |
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KailuaVeeDub
Samba Member
Joined: November 03, 2012
Posts: 35
Location: Kailua Hawaii
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| Posted: Sun Nov 05, 2017 7:05 pm Post subject: Re: How to make a progressive work properly on a VW engine. |
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I have weber progressive on my 76 Baywindow. Confused as to which sized fuel lines to use. 5mm or 7mm? and no need for high pressure, fuel injection line correct?
KP |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50352
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| Posted: Sun Nov 05, 2017 10:11 pm Post subject: Re: How to make a progressive work properly on a VW engine. |
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| KailuaVeeDub wrote: |
I have weber progressive on my 76 Baywindow. Confused as to which sized fuel lines to use. 5mm or 7mm? and no need for high pressure, fuel injection line correct?
KP |
5/16" hose should work fine. You want to run either FI hose or Gate Barricade 30r14 hose, not because of the pressure but because of the alcohol resistance. |
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Steve76063
Samba Member
Joined: August 20, 2011
Posts: 9
Location: DFW Texas :)
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| Posted: Wed Oct 31, 2018 10:40 am Post subject: Re: How to make a progressive work properly on a VW engine. |
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Would this port on a 32/36 Progressive (circled in Red) be the correct place to connect a SVDA distributor, or should it be connected directly to the manifold vacuum (below the carb)? |
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